1.
Egypt
–
Egypt, officially the Arab Republic of Egypt, is a transcontinental country spanning the northeast corner of Africa and southwest corner of Asia by a land bridge formed by the Sinai Peninsula. Egypt is a Mediterranean country bordered by the Gaza Strip and Israel to the northeast, the Gulf of Aqaba to the east, the Red Sea to the east and south, Sudan to the south, and Libya to the west. Across the Gulf of Aqaba lies Jordan, and across from the Sinai Peninsula lies Saudi Arabia, although Jordan and it is the worlds only contiguous Afrasian nation. Egypt has among the longest histories of any country, emerging as one of the worlds first nation states in the tenth millennium BC. Considered a cradle of civilisation, Ancient Egypt experienced some of the earliest developments of writing, agriculture, urbanisation, organised religion and central government. One of the earliest centres of Christianity, Egypt was Islamised in the century and remains a predominantly Muslim country. With over 92 million inhabitants, Egypt is the most populous country in North Africa and the Arab world, the third-most populous in Africa, and the fifteenth-most populous in the world. The great majority of its people live near the banks of the Nile River, an area of about 40,000 square kilometres, the large regions of the Sahara desert, which constitute most of Egypts territory, are sparsely inhabited. About half of Egypts residents live in areas, with most spread across the densely populated centres of greater Cairo, Alexandria. Modern Egypt is considered to be a regional and middle power, with significant cultural, political, and military influence in North Africa, the Middle East and the Muslim world. Egypts economy is one of the largest and most diversified in the Middle East, Egypt is a member of the United Nations, Non-Aligned Movement, Arab League, African Union, and Organisation of Islamic Cooperation. Miṣr is the Classical Quranic Arabic and modern name of Egypt. The name is of Semitic origin, directly cognate with other Semitic words for Egypt such as the Hebrew מִצְרַיִם, the oldest attestation of this name for Egypt is the Akkadian
Egypt
–
The
Giza Necropolis is the oldest of the
ancient Wonders and the only one still in existence.
Egypt
–
Flag
Egypt
–
The Greek Ptolemaic queen
Cleopatra VII and her son by Julius Caesar,
Caesarion at the
Temple of Dendera.
Egypt
–
The 1803
Cedid Atlas, showing
Ottoman Egypt.
2.
Wadi Bani Khalid
–
Wadi Bani Khalid is a wadi about 203 km from Muscat, Oman. It is the best-known wadi of the Sharqiyah region and its stream maintains a constant flow of water throughout the year. Large pools of water and boulders are scattered along the course of the wadi, as a geographical area, Wadi Bani Khalid covers a large swathe of low land and mountains. Caves form some of the features of this wadi. These include Kahf Maqal which is one of the Sultanates underground chambers, however, reaching this cave takes a lot of effort and visitors should be prepared for the adventure. Springs of water are common in this wadi. The springs of Ain Hamouda, Ain al Sarooj and Ain Dawwa, the village of Badaa is a well-known tourist stop in the valley. Media related to Wadi Bani Khalid at Wikimedia Commons
Wadi Bani Khalid
–
Wadi Bani Khalid from above heading east
Wadi Bani Khalid
–
Wadi Bani Khalid heading north
3.
Negev
–
The Negev or Naqab is a desert and semidesert region of southern Israel. The regions largest city and administrative capital is Beersheba, in the north, at its southern end is the Gulf of Aqaba and the resort city of Eilat. It contains several development towns, including Dimona, Arad and Mitzpe Ramon, as well as a number of small Bedouin cities, including Rahat and Tel as-Sabi and Lakyah. There are also several kibbutzim, including Revivim and Sde Boker, the origin of the word negev is from the Hebrew root denoting dry. In the Bible, the word Negev is also used for the direction south, during the British Mandate it was called Beersheba sub-district. The Negev covers more than half of Israel, over some 13,000 km² or at least 55% of the land area. It forms a triangle shape whose western side is contiguous with the desert of the Sinai Peninsula. The Negev has a number of interesting cultural and geological features, among the latter are three enormous, craterlike makhteshim, which are unique to the region, Makhtesh Ramon, Makhtesh Gadol, and Makhtesh Katan. The Negev is a rocky desert and it is a melange of brown, rocky, dusty mountains interrupted by wadis and deep craters. It can be split into five different ecological regions, northern, western and central Negev, the high plateau, the northern Negev, or Mediterranean zone, receives 300 mm of rain annually and has fairly fertile soils. The western Negev receives 250 mm of rain per year, with light, sand dunes can reach heights of up to 30 metres here. The high plateau area of Ramat HaNegev stands between 370 metres and 520 metres above sea level with temperatures in summer and winter. The area gets 100 mm of rain per year, with inferior, the Arabah Valley along the Jordanian border stretches 180 km from Eilat in the south to the tip of the Dead Sea in the north. The Arabah Valley is very arid with barely 50 mm of rain annually and it has inferior soils in which little can grow without irrigation and special soil additives. Vegetation in the Negev is sparse, but certain trees and plants there, among them Acacia, Pistacia, Retama, Urginea maritima. A small population of Arabian leopards, an animal in the Arabian peninsula. The Negev Tortoise is a endangered species that currently lives only in the sands of the western. The Negev shrew is a species of mammal of the family Soricidae found only in Israel, hyphaene thebaica or doum palm can be found in the Southern Negev
Negev
–
Ein Avdat in the Zin Valley in the Negev
Negev
–
Sunset in the Negev Desert near Yeruham, Israel
Negev
–
Nahal Paran, Negev
Negev
–
Spring blooms in the Negev
4.
Arabic language
–
Arabic is a Central Semitic language that was first spoken in Iron Age northwestern Arabia and is now the lingua franca of the Arab world. Arabic is also the language of 1.7 billion Muslims. It is one of six languages of the United Nations. The modern written language is derived from the language of the Quran and it is widely taught in schools and universities, and is used to varying degrees in workplaces, government, and the media. The two formal varieties are grouped together as Literary Arabic, which is the language of 26 states. Modern Standard Arabic largely follows the standards of Quranic Arabic. Much of the new vocabulary is used to denote concepts that have arisen in the post-Quranic era, Arabic has influenced many languages around the globe throughout its history. During the Middle Ages, Literary Arabic was a vehicle of culture in Europe, especially in science, mathematics. As a result, many European languages have borrowed many words from it. Many words of Arabic origin are found in ancient languages like Latin. Balkan languages, including Greek, have acquired a significant number of Arabic words through contact with Ottoman Turkish. Arabic has also borrowed words from languages including Greek and Persian in medieval times. Arabic is a Central Semitic language, closely related to the Northwest Semitic languages, the Ancient South Arabian languages, the Semitic languages changed a great deal between Proto-Semitic and the establishment of the Central Semitic languages, particularly in grammar. Innovations of the Central Semitic languages—all maintained in Arabic—include, The conversion of the suffix-conjugated stative formation into a past tense, the conversion of the prefix-conjugated preterite-tense formation into a present tense. The elimination of other prefix-conjugated mood/aspect forms in favor of new moods formed by endings attached to the prefix-conjugation forms, the development of an internal passive. These features are evidence of descent from a hypothetical ancestor. In the southwest, various Central Semitic languages both belonging to and outside of the Ancient South Arabian family were spoken and it is also believed that the ancestors of the Modern South Arabian languages were also spoken in southern Arabia at this time. To the north, in the oases of northern Hijaz, Dadanitic and Taymanitic held some prestige as inscriptional languages, in Najd and parts of western Arabia, a language known to scholars as Thamudic C is attested
Arabic language
–
The Galland Manuscript of
One Thousand and One Nights, 14th century
Arabic language
–
al-ʿArabiyyah in written Arabic (
Naskh script)
Arabic language
–
Bilingual traffic sign in
Qatar.
Arabic language
–
Examples of how the Arabic root and form system works.
5.
Hebrew language
–
Hebrew is a language native to Israel, spoken by over 9 million people worldwide, of whom over 5 million are in Israel. Historically, it is regarded as the language of the Israelites and their ancestors, the earliest examples of written Paleo-Hebrew date from the 10th century BCE. Hebrew belongs to the West Semitic branch of the Afroasiatic language family, Hebrew is the only living Canaanite language left, and the only truly successful example of a revived dead language. Hebrew had ceased to be a spoken language somewhere between 200 and 400 CE, declining since the aftermath of the Bar Kokhba revolt. Aramaic and to a lesser extent Greek were already in use as international languages, especially among elites and it survived into the medieval period as the language of Jewish liturgy, rabbinic literature, intra-Jewish commerce, and poetry. Then, in the 19th century, it was revived as a spoken and literary language, and, according to Ethnologue, had become, as of 1998, the language of 5 million people worldwide. After Israel, the United States has the second largest Hebrew-speaking population, with 220,000 fluent speakers, Modern Hebrew is one of the two official languages of the State of Israel, while premodern Hebrew is used for prayer or study in Jewish communities around the world today. Ancient Hebrew is also the tongue of the Samaritans, while modern Hebrew or Arabic is their vernacular. For this reason, Hebrew has been referred to by Jews as Leshon Hakodesh, the modern word Hebrew is derived from the word Ivri, one of several names for the Israelite people. It is traditionally understood to be a based on the name of Abrahams ancestor, Eber. This name is based upon the root ʕ-b-r meaning to cross over. Interpretations of the term ʕibrim link it to this verb, cross over, in the Bible, the Hebrew language is called Yәhudit because Judah was the surviving kingdom at the time of the quotation. In Isaiah 19,18 it is called the Language of Canaan, Hebrew belongs to the Canaanite group of languages. In turn, the Canaanite languages are a branch of the Northwest Semitic family of languages, according to Avraham ben-Yosef, Hebrew flourished as a spoken language in the Kingdoms of Israel and Judah during about 1200 to 586 BCE. Scholars debate the degree to which Hebrew was a vernacular in ancient times following the Babylonian exile. In July 2008 Israeli archaeologist Yossi Garfinkel discovered a ceramic shard at Khirbet Qeiyafa which he claimed may be the earliest Hebrew writing yet discovered, dating around 3000 years ago. The Gezer calendar also dates back to the 10th century BCE at the beginning of the Monarchic Period, classified as Archaic Biblical Hebrew, the calendar presents a list of seasons and related agricultural activities. The Gezer calendar is written in an old Semitic script, akin to the Phoenician one that through the Greeks, the Gezer calendar is written without any vowels, and it does not use consonants to imply vowels even in the places where later Hebrew spelling requires it
Hebrew language
–
Hebrew street sign, above in
Hebrew alphabet, below in
Latin transliteration. Aluf Batslut veAluf Shum (he) ("The Onion Champion and the Garlic Champion") is a
play by
Hayim Nahman Bialik.
Hebrew language
–
Portion of the
Temple Scroll, one of the longest of the
Dead Sea Scrolls discovered at
Qumran
Hebrew language
–
The
Shebna Inscription, from the tomb of a royal steward found in
Siloam, dates to the 7th century BCE.
Hebrew language
–
Hebrew script used in writing a Torah scroll. Note ornamental "crowns" on tops of certain letters.
6.
Valley
–
A valley is a low area between hills, often with a river running through it. In geology, a valley or dale is a depression that is longer than it is wide, the terms U-shaped and V-shaped are descriptive terms of geography to characterize the form of valleys. Most valleys belong to one of two main types or a mixture of them, with respect to the cross section of the slopes or hillsides. A valley in its broadest geographic sense is known as a dale. A valley through which a river runs may also be referred to as a vale, a small, secluded, and often wooded valley is known as a dell or in Scotland as a glen. A wide, flat valley through which a river runs is known in Scotland as a strath, a mountain cove is a small valley, closed at one or both ends, in the central or southern Appalachian Mountains which sometimes results from the erosion of a geologic window. A small valley surrounded by mountains or ridges is sometimes known as a hollow, a deep, narrow valley is known as a cwm. Similar geological structures, such as canyons, ravines, gorges, gullies, chines, a valley formed by erosion is called an erosional valley, a valley formed by geologic events such as drop faults or the rise of highlands is called a structural valley. A valley formed by flowing water, or river valley, is usually V-shaped, the exact shape will depend on the characteristics of the stream flowing through it. Rivers with steep gradients, as in mountain ranges, produce steep walls, shallower slopes may produce broader and gentler valleys. However, in the lowest stretch of a river, where it approaches its base level, it begins to deposit sediment, in prehistory, the rivers were used as a source of fresh water and food, as well as a place to wash and a sewer. The proximity of water moderated temperature extremes and provided a source for irrigation, most of the first civilizations developed from these river valley communities. In geography, a vale is a river valley, usually with a particularly wide flood plain or flat valley bottom. In Southern England, vales commonly occur between the escarpment slopes of pairs of chalk formations, where the dome has been eroded, exposing less resistant underlying rock. Rift valleys, such as the Albertine Rift, are formed by the expansion of the Earths crust due to tectonic activity beneath the Earths surface, there are various forms of valley associated with glaciation that may be referred to as glacial valleys. A valley carved by glaciers is normally U-shaped, the valley becomes visible upon the recession of the glacier that forms it. When the ice recedes or thaws, the remains, often littered with small boulders that were transported within the ice. Floor gradient does not affect the shape, it is the glaciers size that does
Valley
–
Calchaquí Valleys in
Argentina
Valley
–
U-shaped valley in
Glacier National Park,
Montana,
USA
Valley
–
Romsdalen in
Western Norway is an almost vertical valley.
Valley
–
Fljótsdalur in East
Iceland, a rather flat valley (in Scotland, this type of valley is called a "strath")
7.
Ephemeral
–
Ephemerality is the concept of things being transitory, existing only briefly. Because different people may value the passage of time differently, the concept of ephemerality is a relative one, an ephemeral waterbody is a wetland, spring, stream, river, pond or lake that only exists for a short period following precipitation or snowmelt. They are not the same as intermittent or seasonal waterbodies, which exist for longer periods, examples of ephemeral streams are the Luni river in Rajasthan, India, Ugab River in Southern Africa, and a number of small ephemeral watercourses that drain Talak in northern Niger. Other notable ephemeral rivers include the Todd River and Sandover River in Central Australia as well as the Son River, Batha River, any endorheic basin, or closed basin, that contains a playa or dry lake at its drainage lowpoint can become an ephemeral lake. Examples include Lake Carnegie in Western Australia, Lake Cowal in New South Wales, Mystic Lake and Rogers Lake in California, even the driest and lowest place in North America, Death Valley, became flooded with a short-lived ephemeral lake in the spring of 2005. There are also ephemeral islands such as Banua Wuhu and Home Reef and these islands appear when volcanic activity increases their height above sea level, but disappear over several years due to wave erosion. Bassas da India, on the hand, is a near-sea level island that appears only at low tide. Many plants are adapted to a lifestyle, in which they spend most of the year or longer as seeds before conditions are right for a brief period of growth. The spring ephemeral plant mouse-ear cress is a well-known example, animals can be ephemeral, with brine shrimp and the mayfly being examples. The placenta is considered an ephemeral organ present during gestation and pregnancy, ephemeral can also be used as an adjective to refer to a fast-deteriorating importance or temporary nature of an object to a person. Brands are notoriously ephemeral assets, and magazine publishing was once much more ephemeral than it is today, a number of art forms can be considered ephemeral because of their temporary nature. Early land art and all sand sculptures, ice sculptures and chalk drawings on footpaths are examples of ephemeral art, G. Augustine Lynas and Duthain Dealbh create ephemeral sculptures. Ephemeroptera Christine Buci-Glucksmann, Esthetique De Lephemere, Galilee, ISBN 2-7186-0622-3
Ephemeral
–
The ephemeral nature of Granite Plateau Creek on the
Mawson Plateau, means the creek is usually a series of waterholes.
Ephemeral
–
Staircase Falls in
Yosemite National Park only flows after heavy rainfall or snowmelt.
Ephemeral
–
Home Reef has repeatedly breached the surface and been subsequently eroded by wave action.
Ephemeral
–
A lake formed at
Badwater within
Death Valley National Park during the unusually wet winter and spring of 2005
8.
Stream bed
–
A stream bed is the channel bottom of a stream, river or creek, the physical confine of the normal water flow. The lateral confines or channel margins are known as the banks or river banks, during all. Under certain conditions a river can branch from one bed to multiple stream beds. A flood occurs when a stream overflows its banks and flows onto its flood plain, as a general rule, the bed is the part of the channel up to the normal water line, and the banks are that part above the normal water line. However, because water flow varies, this differentiation is subject to local interpretation, the nature of any stream bed is always a function of the flow dynamics and the local geologic materials, influenced by that flow. With small streams in mesophytic regions, the nature of the bed is strongly responsive to conditions of precipitation runoff. Where natural conditions of either grassland or forest ameliorate peak flows, stream beds are stable, possibly rich, with organic matter and these streams support a rich biota. Where conditions produce unnatural levels of runoff, such as occurs below roads and this process greatly increases watershed erosion and results in thinner soils, upslope from the stream bed, as the channel adjusts to the increase in flow. The stream bed is very complex in terms of erosion, sediment is transported, eroded and deposited on the stream bed. With global warming there is a fear that the size and shape of riverbeds will change due to increased flood magnitude and this shows that the stream bed is left mostly unchanged in size and shape. Dry stream beds are also subject to becoming underground water pockets and flooding by heavy rains and water rising from the ground and may sometimes be part of the rejuvenation of the stream
Stream bed
–
The bed of this stream is
armored with rocks, some very rounded (having had a longer life in the stream) and some not.
Stream bed
–
The old bed of the
Mississippi River near
Kaskaskia, Illinois, left behind after the river shifted
Stream bed
–
A woman digs in a dry stream bed in
Kenya to find water during a drought.
Stream bed
–
General
9.
Morocco
–
Morocco, officially known as the Kingdom of Morocco, is a sovereign country located in the Maghreb region of North Africa. Geographically, Morocco is characterized by a mountainous interior, large tracts of desert. Morocco has a population of over 33.8 million and an area of 446,550 km2 and its capital is Rabat, and the largest city is Casablanca. Other major cities include Marrakesh, Tangier, Tetouan, Salé, Fes, Agadir, Meknes, Oujda, Kenitra, a historically prominent regional power, Morocco has a history of independence not shared by its neighbours. Marinid and Saadi dynasties continued the struggle against foreign domination, the Alaouite dynasty, the current ruling dynasty, seized power in 1666. In 1912 Morocco was divided into French and Spanish protectorates, with a zone in Tangier. Moroccan culture is a blend of Arab, indigenous Berber, Sub-Saharan African, Morocco claims the non-self-governing territory of Western Sahara as its Southern Provinces. Morocco annexed the territory in 1975, leading to a war with indigenous forces until a cease-fire in 1991. Peace processes have thus far failed to break the political deadlock, Morocco is a constitutional monarchy with an elected parliament. The King of Morocco holds vast executive and legislative powers, especially over the military, foreign policy, the king can issue decrees called dahirs which have the force of law. He can also dissolve the parliament after consulting the Prime Minister, Moroccos predominant religion is Islam, and the official languages are Arabic and Tamazight. The Moroccan dialect, referred to as Darija, and French are also widely spoken, Morocco is a member of the Arab League, the Union for the Mediterranean, and the African Union. It has the fifth largest economy of Africa, the full Arabic name al-Mamlakah al-Maghribiyyah translates to Kingdom of the West, although the West in Arabic is الغرب Al-Gharb. The basis of Moroccos English name is Marrakesh, its capital under the Almoravid dynasty, the origin of the name Marrakesh is disputed, but is most likely from the Berber words amur akush or Land of God. The modern Berber name for Marrakesh is Mṛṛakc, in Turkish, Morocco is known as Fas, a name derived from its ancient capital of Fes. The English name Morocco is an anglicisation of the Spanish Marruecos, the area of present-day Morocco has been inhabited since Paleolithic times, sometime between 190,000 and 90,000 BC. During the Upper Paleolithic, the Maghreb was more fertile than it is today, twenty-two thousand years ago, the Aterian was succeeded by the Iberomaurusian culture, which shared similarities with Iberian cultures. Skeletal similarities have been suggested between the Iberomaurusian Mechta-Afalou burials and European Cro-Magnon remains, the Iberomaurusian was succeeded by the Beaker culture in Morocco
Morocco
–
Berber Roman King
Ptolemy of Mauretania.
Morocco
–
Flag
Morocco
–
Roman mosaic of Diana in
Volubilis.
Morocco
–
Morocco, Safi ceramic vessel Jobbana
10.
Andalusian Arabic
–
It became an extinct language in Iberia after the expulsion of the Moriscos, which took place over a century after the Conquest of Granada by Christian Spain. Andalusi Arabic is still used in Andalusi music and has influenced the dialects of such towns as Sfax in Tunisia, Fez, Rabat, Nedroma, Tlemcen, Blida. It is still used by communities of the descendants of Moriscos in cities like Tangiers and Tetouan in Morocco and Testour, Ghar al Milh and Sfax in Tunisia which welcomed Moriscos refugees. It also exerted influence on Mozarabic, Spanish, Ladino, Catalan, Portuguese, Classical Arabic. Andalusian Arabic appears to have spread rapidly and been in general use in most parts of Al-Andalus between the 9th and 15th centuries. In 1502, the Muslims of Granada were forced to choose between conversion and exile, those who converted became known as the Moriscos, in 1526, this requirement was extended to the Muslims elsewhere in Spain. In 1567, Philip II of Spain issued a decree in Spain forbidding Moriscos from the use of Arabic on all occasions, formal and informal. Using Arabic in any sense of the word would be regarded as a crime and they were given three years to learn a Christian language, after which they would have to get rid of all Arabic written material. This triggered one of the largest Morisco Revolts, still, Andalusian Arabic remained in use in certain areas of Spain until the final expulsion of the Moriscos at the beginning of the 17th century. The phoneme represented by the letter ق in texts is a point of contention, contact with native Romance speakers led to the introduction of the phonemes /p/, /ɡ/ and, possibly, the affricate /tʃ/ from borrowed words. There was an amount of compensatory lengthening involved where a loss of consonantal gemination lengthened the preceding vowel. The -an which, in Classical Arabic, marked a noun as indefinite accusative, became an indeclinable conjunctive particle, the unconjugated prepositive negative particle lis developed out of the classical verb lays-a. The derivational morphology of the system was substantially altered. Whence the initial n- on verbs in the first person singular, likewise the form V pattern of tafaʻʻal-a was altered by epenthesis to atfaal. 317–323, doi,10. 2307/1580571, JSTOR1580571 Corriente, Frederico, Los fonemas /p/ /č/ y /g/ en árabe hispánico, Vox Romanica,37, pp. 214–18
Andalusian Arabic
–
Andalusian Arabic
11.
Guadalcanal, Seville
–
Guadalcanal is a village in the province of Seville, in the autonomous community of Andalusia, Spain. The name was given to the island of Guadalcanal in the Solomon Islands in 1568, the name was chosen by Pedro de Ortega Valencia who had been born in the village. He was a subordinate of Spanish explorer and navigator, Álvaro de Mendaña de Neira, in 2006 there were 2,970 inhabitants. It has an area of 275 square kilometres and a density of 10,6 people per square-km. It is at an altitude of 662 metres, in a valley between the Sierra del Agua and the Sierra del Viento, in the region of the North Mountains of Seville, but it is more likely to be a mixture of Arabic Wad and Spanish del Canal. Other names were Tereses or Tereja or Canani with the Iberians and it was reconquered by the Order of Santiago in 1241 from the Moors, then Guadalcanal belonged to the Leóns province as well as other parts of Extremadura. In the ecclesiastical matter, it belonged to the Santa María de Tendudia vicary, Guadalcanal was fortified by means of a now-ruined wall which was demolished because the village took part in the Guerra de las Comunidades de Castilla. In the mid-16th century, the area had some silver mines financed by the Fugger family, the village suffered a crisis in the 19th century, which caused the four nunneries in the village to close. As other rural communities in Spain, it faced an exodus of its inhabitants to the cities in the 20th century. Página web del pintor Fernando Díaz Mirón Mirador La Capitana en el término municipal de Guadalcanal Vídeos de Guadalcanal
Guadalcanal, Seville
–
Guadalcanal
Guadalcanal, Seville
–
Ermita de San Benito.
Guadalcanal, Seville
–
Guadalcanal. Iglesia de Santa Ana.
Guadalcanal, Seville
–
Guadalcanal. Iglesia de la Concepción.
12.
Guadalajara, Spain
–
Guadalajara is a city and municipality in the autonomous community of Castile–La Mancha, Spain, and in the natural region of La Alcarria. It is the capital of the province of Guadalajara and it is located roughly 60 kilometres northeast of Madrid on the Henares River, and has a population of 84,803. A Roman town called Arriaca, possibly founded by a culture, is known to have been located in that region. There is however no proof of its existence, only references in texts such as the Ruta Antonina. The city, as Caracca, was incorporated into the Roman province of Hispania Tarraconensis, the city was on the high road from Emerita to Caesaraugusta,22 M. P. northeast of Complutum. The town of Guadalajara was founded by the Andalusians in the 8th century and they named it Wādī-al-Ḥajāra, meaning Valley of Stones, in theory the literal translation of the Iberian name, meaning Stony River. The history of the town during the Al-Andalus period was significant and they built monuments including the Moorish Bridge over the Henares River, the now ruined old Alcázar, and a mosque which later became the former Cathedral of St. Mary. In 1085, Guadalajara was taken by the Christian forces of Alfonso VI, the chronicles say that the Christian army was led by Alvar Fanez de Minaya, one of the lieutenants of El Cid. From 1085 until the Battle of Las Navas de Tolosa in 1212, the city suffered wars against the Almoravid, in 1219, the king Fernando III gave a new fuero to the city. During the reign of Alfonso X of Castile, the protection of the king allowed the city to develop its economy by protecting merchants, during the 14th century, the Mendoza family was prominent in Guadalajara. This family included Íñigo López de Mendoza, also known as Marqués de Santillana, the Mendoza family held the title of Dukes and Duchesses of El Infantado from 1475. In 1460, King Henry IV gave Guadalajara the title of City, Guadalajara was the birthplace of conquistador Nuño de Guzmán, who commissioned in 1542 the foundation of Guadalajara, Mexico. During the War of the Spanish Succession, Guadalajara was sacked, King Philip V ordered the establishment of the Real Fábrica de Paños which was situated in the Alcazar till the early 19th century. In this period, the Mendoza Family ordered the building of El Palacio del Infantado as their main residence and it was completed in the early 1480s and it is considered by many the oldest surviving building built in a pure Renaissance style outside Italy. The 19th century started with two setbacks, the damages caused by the Peninsular War and the closing of the Real Fábrica de Paños in 1822. In 1808, Guadalajara was taken by the French Army led by General Hugo, in 1840 Guadalajara was established as the capital of the province with the same name by the Plan de Burgos. The Academy of Military Engineers was brought to the city, Guadalajara was the scene of many actions during the Spanish Civil War. On 24 July 1936, during the phase after the revolt of 19 July
Guadalajara, Spain
–
Remains of the "Alcázar of Guadalajara", built in the 9th century
Guadalajara, Spain
–
Flag
Guadalajara, Spain
–
The
medieval 'Torreón de Álvar Fáñez'
Guadalajara, Spain
–
'Concatedral de Santa María de Guadalajara', was built in the 13th and 14th centuries
13.
Guadalquivir
–
The Guadalquivir is the fifth longest river in the Iberian Peninsula and the second longest river with its entire length in Spain. The Guadalquivir river is the only navigable river in Spain. Currently it is navigable to Seville, but in Roman times it was navigable to Córdoba, the Guadalquivir is 657 km long and drains an area of about 58,000 km2. The marshy lowlands at the end are known as Las Marismas. The river borders Doñana National Park reserve, the modern name of Guadalquivir comes from the Arabic al-wādi al-kabīr, great valley. Classical Arabic Wadi is pronounced in present-day Maghrebi Arabic as Oued, there were a variety of names for the Guadalquivir in Classical and pre-Classical times. Baetis was its name to the Romans, and Greek geographers sometimes called it the river of Tartessus, before Phoenician, Greek, and Roman colonists arrived, two indigenous names for the river may have been Kertis/Certis and Rérkēs. The Phoenicians established the first anchorage grounds and dealt in precious metals, the ancient city of Tartessos was said to have been located at the mouth of the Guadalquivir, although its site has not yet been found. The Romans, whose name for the river was Betis Baetis, settled in Hispalis, in the 2nd century BC, by the 1st century BC Hispalis was a walled city with shipyards building longboats to carry wheat. In the 1st century AD the Hispalis was home to entire naval squadrons, ships sailed to Rome with various products, minerals, salt, fish, etc. During Arab rule between 712 and 1248, the Moors left a stone dock and the Torre del Oro, a reconstructed waterwheel is located at Córdoba on the Guadalquivir River. The Molino de la Albolafia waterwheel originally built by the Romans provided water for the nearby Alcázar gardens as well as being used to mill flour. After the discovery of the Americas, Seville became the centre of the Spanish Empire as its port monopolised the trans-oceanic trade. As navigation of the Guadalquivir River became increasingly difficult Sevilles trade monopoly was transferred to Cádiz, the construction of the artificial canal known as the Corta de Merlina in 1794 marked the beginning of the modernisation of the port of Seville. In late November 2010 the new Seville lock began to function as a regulator of the tides after five years of work, the Guadalquivir River Basin occupies an area of 63,085 km2 and has a long history of severe flooding. During the winter of 2010 heavy rainfall caused flooding in rural and agricultural areas in the provinces of Seville, Córdoba. The accumulated rainfall in the month of February was above 250 mm and this was below that recorded in Seville in the flood of 1963 when a volume of 6,000 m3/s. was reached. During August 2010 when flooding occurred in Jaén, Córdoba and Seville, the Doñana disaster, also known as the Aznalcóllar Disaster or Guadiamar Disaster was an industrial accident in Andalusia
Guadalquivir
–
Guadalquivir River near
Coria del Río Seville
Guadalquivir
–
1892 flood in Seville
Guadalquivir
–
Reconstructed waterwheel at Cordoba
Guadalquivir
–
Roman Bridge at Cordoba
14.
Hindustani language
–
Hindustani, historically also known as Hindavi, Dehlvi and Rekhta, is the lingua franca of North India and Pakistan. It is an Indo-Aryan language, deriving primarily from the Khariboli dialect of Delhi, before the Partition of the British Indian Empire, the terms Hindustani, Urdu, and Hindi were synonymous, all covered what would be called Urdu and Hindi today. Hindustani is also spoken by a number of people in Mauritius. Early forms of present-day Hindustani developed from the Middle Indo-Aryan apabhramsha vernaculars of present-day North India in the 7th–13th centuries. Amir Khusro, who lived in the 13th century CE during the Delhi Sultanate period in North India, used these forms in his writings, the Delhi Sultanate, which comprised several Turkic and Afghan dynasties that ruled from Delhi, was succeeded by the Mughal Empire in 1526. The basis in general for the introduction of Persian language into the subcontinent was set, from its earliest days, by various Persianised Central Asian Turkic, the term Hindustani was the name given to that variant of Khariboli. For socio-political reasons, though essentially the variant of Khariboli with Persian vocabulary, the more highly Persianised version later established as a language of the court was called Rekhta, or mixed. As an emerging common dialect, Hindustani absorbed large numbers of Persian, Arabic, and Turkic words and its development was centred on the poets of the Mughal courts of cities in Uttar Pradesh such as Delhi, Lucknow, and Agra. He continued, But it has all the magnitude and importance of separate language and it is linguistic result of Mohammedan invasions of eleventh & twelfth centuries and is spoken by many Hindus in North India and by Musalman population in all parts of India. Next to English it was the language of British Indian Empire, was commonly written in Arabic or Persian characters. When the British colonised the Indian subcontinent from the late 18th through to the late 19th century, they used the words Hindustani, Hindi and they developed it as the language of administration of British India, further preparing it to be the official language of modern India and Pakistan. However, with independence, use of the word Hindustani declined, being replaced by Hindi and Urdu. It has a literature of 500 years, with prose, poetry, religion & philosophy, under the Bahmani Kings and it is a living language, still prevalent all over the Deccan Plateau. Note that the term Hindustani has generally fallen out of usage in modern India, except to refer to Indian as a nationality. The term used to refer to it is Hindi or Urdu, depending on the religion of the speaker, in common usage in India, the term Hindi includes all these dialects except those at the Urdu end of the spectrum. Urdu is the language of Pakistan and an officially recognised regional language of India. It is also a language in the Indian states of Jammu and Kashmir, National Capital Territory of Delhi, Uttar Pradesh, Bihar. In a specific sense, Hindustani may be used to refer to the dialects and varieties used in speech, in contrast with the standardised Hindi
Hindustani language
–
Rigveda manuscript in Devanagari (early 19th century)
Hindustani language
–
Hindustani
Hindustani language
–
Hindustani, in its standardised registers, is one of the official languages of both India (Hindi) and Pakistan (Urdu).
15.
Urdu
–
Urdu is a persianized standard register of the Hindustani language. It is the language and lingua franca of Pakistan. It is also one of the 22 official languages recognized in the Constitution of India, hyderabad, Rampur, Bhopal and Lucknow are noted Urdu-speaking cities of India. Urdu is historically associated with the Muslims of the northern Indian subcontinent, apart from specialized vocabulary, Urdu is mutually intelligible with Standard Hindi, another recognized register of Hindustani. Urdu, like Hindi, is a form of Hindustani, Urdu developed under the influence of the Persian and Arabic languages, both of which have contributed a significant amount of vocabulary to formal speech. Around 99% of Urdu verbs have their roots in Sanskrit and Prakrit, Urdu words originating from Chagatai and Arabic were borrowed through Persian and hence are Persianized versions of the original words. For instance, the Arabic ta marbuta changes to he or te, nevertheless, contrary to popular belief, Urdu did not borrow from the Turkish language, but from Chagatai. Urdu and Turkish borrowed from Arabic and Persian, hence the similarity in pronunciation of many Urdu, Arabic influence in the region began with the late first-millennium Arab invasion of India in the 7th century. The Persian language was introduced into the subcontinent a few centuries later by various Persianized Central Asian Turkic and Afghan dynasties including that of the Delhi Sultanate. With the advent of the British Raj, Persian was no longer the language of administration but Hindustani, still written in the Persian script, the name Urdu was first used by the poet Ghulam Hamadani Mushafi around 1780. From the 13th century until the end of the 18th century Urdu was commonly known as Hindi, the language was also known by various other names such as Hindavi and Dehlavi. The communal nature of the language lasted until it replaced Persian as the language in 1837 and was made co-official. Urdu was promoted in British India by British policies to counter the previous emphasis on Persian and this triggered a Brahman backlash in northwestern India, which argued that the language should be written in the native Devanagari script. At independence, Pakistan established a highly Persianized literary form of Urdu as its national language, English has exerted a heavy influence on both as a co-official language. Owing to interaction with other languages, Urdu has become localized wherever it is spoken, similarly, the Urdu spoken in India can also be distinguished into many dialects like Dakhni of South India, and Khariboli of the Punjab region since recent times. Because of Urdus similarity to Hindi, speakers of the two languages can understand one another if both sides refrain from using specialized vocabulary. The syntax, morphology, and the vocabulary are essentially identical. Thus linguists usually count them as one language and contend that they are considered as two different languages for socio-political reasons
Urdu
–
Autograph and a couplet of Last
Mughal Emperor,
Bahadur Shah II, dated 29 April 1844
Urdu
–
Urdu in
Perso-Arabic script (
Nastaliq style)
Urdu
–
A trilingual
signboard in the
UAE
Urdu
–
A multilingual
New Delhi railway station board
16.
Hindi
–
Hindi, or Modern Standard Hindi is a standardised and Sanskritised register of the Hindustani language. Along with the English language, Hindi written in the Devanagari script, is the language of the Government of India. It is also one of the 22 scheduled languages of the Republic of India, Hindi is the lingua franca of the so-called Hindi belt of India. Outside India, it is a language which is known as Fiji Hindi in Fiji, and is a recognised regional language in Mauritius, Trinidad and Tobago, Guyana. Hindi is the fourth most-spoken first language in the world, after Mandarin, apart from specialized vocabulary, Hindi is mutually intelligible with Standard Urdu, another recognized register of Hindustani. Part XVII of the Indian Constitution deals with Official Language, under Article 343, official language of the Union has been prescribed, which includes Hindi in Devanagari script and English. Gujarat High Court, in 2010, has observed that there was nothing on record to suggest that any provision has been made or order issued declaring Hindi as a language of India. Article 343 of the Indian constitution states The official language of the Union shall be Hindi in Devanagari script, the form of numerals to be used for the official purposes of the Union shall be the international form of Indian numerals. It was envisioned that Hindi would become the working language of the Union Government by 1965. Each may also designate a co-official language, in Uttar Pradesh, for instance, depending on the formation in power. Similarly, Hindi is accorded the status of language in the following Union Territories, Andaman & Nicobar Islands, Chandigarh, Dadra & Nagar Haveli, Daman & Diu. National-language status for Hindi is a long-debated theme, an Indian court clarified that Hindi is not the national language of India because the constitution does not mention it as such. Outside Asia, Hindi is a language in Fiji as per the 1997 Constitution of Fiji. It is spoken by 380,000 people in Fiji, Hindi is also spoken by a large population of Madheshis of Nepal. Hindi is quite easy to understand for some Pakistanis, who speak Urdu, apart from this, Hindi is spoken by the large Indian diaspora which hails from, or has its origin from the Hindi Belt of India. Like other Indo-Aryan languages, Hindi is considered to be a descendant of an early form of Sanskrit, through Sauraseni Prakrit. It has been influenced by Dravidian languages, Turkic languages, Persian, Arabic, Portuguese, Hindi emerged as Apabhramsha, a degenerated form of Prakrit, in the 7th century A. D. By the 10th century A. D. it became stable, Braj Bhasha, Bhojpuri, Awadhi, Khari Boli etc. are the dialects of Hindi
Hindi
–
The word "Hindi" in
Devanagari script
17.
Maghreb
–
The Maghreb, or the Greater Maghreb, is usually defined as much or most of the region of western North Africa or Northwest Africa, west of Egypt. Historical terms for the region or various portions of the Maghreb include Mauretania, Numidia, Libya, the term maghrib is Arabic for west, from the verb gharaba. In the strict sense, the definite form al-maghrib denotes the country of Morocco in particular and it identified the westernmost territories that fell to the Islamic conquests of the 7th century. Today, it is a noun for the present region of the Maghreb. The Berber languages alternative term for the region, Tamazgha, has been popularized by Berber activists since the second half of the 20th century. As recently as the late 19th century it was used to refer to the Western Mediterranean region of coastal North Africa in general, and to Algeria, Morocco and Tunisia in particular. The region was unified as an independent political entity during the rule of the Berber kingdom of Numidia. The most enduring rule was that of the local Berber empires of the Almoravids, Almohads, Hammadids, Zirids, Marinids, Saadi, the Ottoman Turks ruled the region as well. Mauritania, Morocco, Tunisia, Algeria, and Libya established the Maghreb Union in 1989 to promote cooperation and it was envisioned initially by Muammar Gaddafi as a superstate. The union included Western Sahara implicitly under Moroccos membership, putting Moroccos long cold war with Algeria to a rest, however, this progress was short-lived, and the union is now frozen. Tensions between Algeria and Morocco over Western Sahara re-emerged strongly, reinforced by the unsolved borderline issue between the two countries and these two main conflicts have hindered progress on the unions joint goals and practically made it inactive as a whole. Around 3,500 BC a tilt in the Earths orbit created a rapid desertification of the Sahara, the Maghreb or western North Africa is believed to have been inhabited by Berbers since from at least 10,000 BC. Maghreb coast ports were predominantly occupied or constructed by the Phoenicians, the main Phoenician settlements centered in the Gulf of Tunis along the North African littoral between the Pillars of Hercules and the Libyan coast east of ancient Cyrenaica. They dominated the trade and intercourse of the Western Mediterranean for centuries, Rome was greatly helped by the defection of King Massinissa and Carthaginians eastern Numidian Massylii client-allies. A century later, the Byzantine emperor Justinian I sent a force under General Belisarius that succeeded in destroying the Vandal kingdom, the Berbers contested outside-the-area control although after the 640s-700 AD period the Arabs controlled the entire region. The Arabs reached the Maghreb in early Umayyad times, Arab expansion and the spread of Islam pushed the development of trans-Saharan trade. While restricted due to the cost and dangers, the trade was highly profitable, commodities traded included such goods as salt, gold, ivory, and slaves. Arab control over the Maghreb was quite weak, various Islamic variations, such as the Ibadis and the Shia, were adopted by some Berbers, often leading to scorning of Caliphal control in favour of their own interpretation of Islam
Maghreb
–
Magreb head ornament (Morocco)
Maghreb
–
The
Arab Maghreb Union countries
Maghreb
–
The
Great Mosque of Kairouan, founded by the Arab general Uqba Ibn Nafi (in 670), is the oldest mosque in the Maghreb city of
Kairouan,
Tunisia.
Maghreb
–
1707 map of northwest Africa by
Guillaume Delisle, including the Maghreb
18.
Maghrebi Arabic
–
Maghrebi Arabic, or Maghrebi Darija, is the principal spoken language in the Maghreb region, including Morocco, Algeria, Tunisia and Libya. Its also called Western Arabic that includes Moroccan Arabic, Algerian Arabic, in Algeria, the Maghrebi as a colloquial language was taught as a separate subject under French colonization, and some textbooks exist. Speakers of Maghrebi call their language Derja, Derija or Darija and it is used as a spoken and sometimes as a written language for communication. Maghrebi Arabic is used as well in TV dramas and on advertising boards in Algeria, Morocco and Tunisia, the varieties of Maghrebi Arabic Darija have a significant degree of mutual intelligibility, specially between geographically adjacent ones but hardly between the Moroccan and Tunisian Darija. Conversely, the Moroccan Darija cannot be understood by Eastern Arabic speakers in general as it does derive from different substratums, a considerable number of linguists like Charles A. Ferguson, William Marçais and Abdou Elimam, tend to consider Maghrebi Arabic Darija as an independent language. Maghrebi dialects all use n- as the singular prefix on verbs, distinguishing them from Levantine dialects. Speakers frequently borrow words from French, Spanish and Italian and conjugate them according to the rules of Arabic with some exceptions, since it is not always written, there is no standard and it is free to change quickly and to pick up new vocabulary from neighbouring languages. This is somewhat similar to what happened to Middle English after the Norman conquest, linguistically, Siculo-Arabic and therefore its descendant Maltese are considered Maghrebi, but they are no longer mutually intelligible with the varieties spoken today in North Africa. When discussing modern languages, the word is given a geographic definition. It refers to any of the varieties of colloquial Maghrebi Arabic, for instance, Algerian Arabic would be referred as Dzayri and Tunisian Arabic as Tounsi, and Egyptian Arabic would be referred as Masri and Lebanese Arabic as Lubnani. Singer, Hans-Rudolf “Das Westarabische oder Maghribinische” in Wolfdietrich Fischer and Otto Jastrow Handbuch der arabischen Dialekte
Maghrebi Arabic
–
An overview of the different
Arabic dialects. Maghrebi varieties are shades of blue.
19.
Alluvial fan
–
An alluvial fan is a fan- or cone-shaped deposit of sediment crossed and built up by streams. If a fan is built up by debris flows it is called a debris cone or colluvial fan. These flows come from a point source at the apex of the fan. Fans are typically found where a canyon draining from mountainous terrain emerges out onto a flatter plain, a convergence of neighboring alluvial fans into a single apron of deposits against a slope is called a bajada, or compound alluvial fan. As a streams gradient decreases, it drops coarse-grained material and this reduces the capacity of the channel and forces it to change direction and gradually build up a slightly mounded or shallow conical fan shape. The deposits are poorly sorted. There will be iso-transport energy lines forming concentric arcs about the point at the apex of the fan. Thus the material will tend to be deposited equally about these lines, Alluvial fans are often found in desert areas subject to periodic flash floods from nearby thunderstorms in local hills. The typical watercourse in an arid climate has a large, funnel-shaped basin at the top, leading to a narrow defile, multiple braided streams are usually present and active during water flows. Phreatophytes are plants that are concentrated at the base of alluvial fans. They have long tap roots 30 to 50 feet to water that has seeped through the fan and hit an impermeable layer, sometimes collecting in springs. These stands of shrubs cling to the soil at their bases, Alluvial fans also develop in wetter climates. Along the upper Koshi tributaries, tectonic forces elevate the Himalayas several millimeters annually, uplift is approximately in equilibrium with erosion, so the river annually carries some 100 million cubic meters of sediment as it exits the mountains. Deposition of this magnitude over millions of years is more than sufficient to account for the megafan, despite overpopulation on the plains, this bhabar zone is highly malarial and has remained largely uninhabited. In North America, streams flowing into Californias Central Valley have deposited smaller, such as that of the Kings River flowing out of the Sierra Nevada creates a low divide, turning the south end of the San Joaquin Valley into an endorheic basin without a connection to the ocean. Alluvial fans are subject to flooding and can be more dangerous than the upstream canyons that feed them. Their slightly convex perpendicular surfaces cause water to spread widely until there is no zone of refuge, if the gradient is steep, active transport of materials down the fan creates a moving substrate that is inhospitable to travel on foot or wheels. But as the gradient diminishes downslope, water comes down from above faster than it can flow away downstream, in the case of the Koshi River, the huge sediment load and megafans slightly convex transverse surface conspire against engineering efforts to contain peak flows inside manmade embankments
Alluvial fan
–
A vast (60 km long) alluvial fan blossoms across the desolate
landscape between the
Kunlun and
Altun mountain ranges that form the southern border of the
Taklamakan Desert in
Xinjiang. The left side is the active part of the fan, and appears blue from
water flowing in the many small
streams
Alluvial fan
–
Alluvial fan in
Death Valley
Alluvial fan
–
Alluvial fan above
Lake Louise,
Alberta, Canada.
Alluvial fan
–
Ground-level view of a large alluvial fan in
Death Valley
20.
Sabkha
–
Sabkha is a phonetic translation of the Arabic word for a salt flat. Sabkhas are supratidal, forming along coastlines and are characterized by evaporite-carbonate deposits with some siliciclastics. Sabkhas form subaerial, prograding and shoaling-upward sequences that have a thickness of a meter or less. The accepted type locality is along the coast of the Persian Gulf in the United Arab Emirates, the origin and progression of sabkha development in the Persian Gulf is discussed by Al-Farraj. In the khor-lagoon-sabkha model, a rise in sea-level floods coastal areas. If the features silt up, or the land rises, or the sea level falls, then the water evaporates, leaving a flat salt pan. If the coastal region has irregular topography, then the flooding creates large independent creeks, a khor is a shallow, subtidal flat or tidal inlet. The inlet may host grey mangroves, depending on whether less saline water is available from wadis or groundwater, as sediment begins to accumulate, the khors become more shallow and form a lagoon, or intertidal flat. The lagoons continue to fill until the floor is exposed at low tide. An immature sabkha will be inundated during higher than normal spring tides, after rainstorms, mature sabkhas are only flooded after heavy rainstorms and may eventually coalesce to form a sabkha coastal plain. These coastal plains are flat, with reliefs between 10–50 cm, and their seaward slope can be as little as 1,1,000. The flatness of a sabkha is enhanced by aeolian siliciclastic dust being deposited in the topographic lows with most of the caused by evaporites. These environments can be found laterally contemporaneous in parallel belts to the coast as well, coral reefs, barrier islands, and oolite shoals form the barrier with the open shelf. Inland of this are the supratidal sabkhas, the sabkhas can be as wide as 15 km when seaward of dune fields supplying large amounts of sediment. Sabkhas seaward of low outcrops of Miocene carbonate-evaporites or alluvial fans off the Oman fold, if the coast has dune fields, then flooding creates many smaller pools between the crests of the dunes. In some parts of the world, these lakes can form in inland deserts. For example, large parts of the Empty Quarter in Saudi Arabia, in some places, the sabkha connect to form long accessible corridors into the desert. The third picture shows the south of the crescent-shaped Liwa Oasis in the southern UAE
Sabkha
–
Sebkhat (or Sebkha) El Melah, Tunisia in 2001, mostly dry. Note rectangular industrial evaporite pans, probably for sea-salt production, upper right.
Landsat 7 image.
Sabkha
–
Dunes and salt flats in the
Empty Quarter - 1.
Sabkha
–
Dunes and salt flats in the
Empty Quarter - 2.
Sabkha
–
Dunes and salt flats south of the crescent-shaped
Liwa Oasis (UAE).
21.
Dry lake
–
A dry lake is an ephemeral lakebed, or a remnant of an endorheic lake. Such flats consist of fine-grained sediments infused with alkali salts, alternative names for the dry lake include alkali flat, alkali sink and playa. A playa lake may cover an area, but it is never deep. Most water in it evaporates, leaving a layer of salt on the surface and these salt covered stretches are called saltpans. The surface of a dry lake is dry, hard and rough during the dry season. Dry lakes are small, round depressions in the surface of the landscape. If its basin is primarily salt, then a dry lake is called a salt pan, pan, hardpan, another dry lake type is the mudflat. Hardpan is the dry terminus of an internally drained basin in a dry climate, the Spanish word playa literally means beach. Dry lakes are known by name in some parts of Mexico. This term is used on the Llano Estacado and other parts of the Southern High Plains. In South America, the term for a dry lake is salar or salina. Pan is the used in most of South Africa. These may include the small round pans, typical of the Chrissiesmeer area, to the extensive pans of the Northern Cape province. It is also used in Australia, distinguished are salt pans and clay pans. In Arabic, a flat is called a sabkha or shott. In Central Asia, a similar cracked mud salt flat is known as a takyr, in Iran salt flats are called kavir. A playa lake is formed when water from rain or other sources, like intersection with a table, flows into a dry depression in the landscape. If the total annual evaporation rate exceeds the annual inflow
Dry lake
–
Namak Lake,
Qom Province,
Iran
Dry lake
–
The
Chott el Djerid in
Tunisia
Dry lake
–
Salt harvesting in
Salar de Uyuni,
Bolivia, the world's largest salt flat
Dry lake
–
Sailing stone in
Racetrack Playa
22.
Flash flood
–
A flash flood is a rapid flooding of geomorphic low-lying areas, washes, rivers, dry lakes and basins. It may be caused by heavy rain associated with a thunderstorm, hurricane, tropical storm. Flash floods may occur after the collapse of an ice or debris dam, or a human structure such as a man-made dam. Flash floods are distinguished from regular floods by a timescale of less than six hours, the water that is temporarily available is often used by foliage with rapid germination and short growth cycles, and by specially adapted animal life. Flash floods can occur under several types of conditions, Flash flooding occurs when it rains rapidly on saturated soil or dry soil that has poor absorption ability. The runoff collects in gullies and streams and, as they join to form larger volumes, often forms a fast flowing front of water, in areas on or near volcanoes, flash floods have also occurred after eruptions, when glaciers have been melted by the intense heat. Flash floods are known to occur in the highest mountain ranges of the United States and are common in the arid plains of the Southwestern United States. Flash flooding can also be caused by extensive rainfall released by hurricanes and other tropical storms, human activities can also cause flash floods to occur. When dams fail, a quantity of water can be released. Many people tend to underestimate the dangers of flash floods, what makes flash floods most dangerous is their sudden nature and fast-moving water. A vehicle provides little to no protection against being swept away, it may make people overconfident, more than half of the fatalities attributed to flash floods are people swept away in vehicles when trying to cross flooded intersections. As little as 2 feet of water is enough to carry away most SUV-sized vehicles. The U. S. National Weather Service reported in 2005 that, using a national 30-year average, more people die yearly in floods,127 on average, than by lightning, tornadoes, in deserts, flash floods can be particularly deadly for several reasons. First, storms in arid regions are infrequent, but they can deliver an enormous amount of water in a short time. Second, these rains often fall on poorly absorbent and often clay-like soil, in fact, in some areas, desert roads frequently cross dry river and creek beds without bridges. From the drivers perspective, there may be clear weather, when a river unexpectedly forms ahead of or around the vehicle in a matter of seconds. Finally, the lack of rain to clear water channels may cause flash floods in deserts to be headed by large amounts of debris, such as rocks, branches. 1889, Johnstown Flood, Pennsylvania, U. S. more than 2,200 people dead 1903, Heppner Flood of 1903, Oregon, United States,247 dead, 25% of the city 1938, Los Angeles Flood of 1938, California, U. S. S
Flash flood
–
Driving through a flash-flooded road
Flash flood
–
Nepal Monsoon
Flash flood
–
A flash flood after a thunderstorm in the
Gobi, Mongolia
23.
Loess
–
Loess is a clastic, predominantly silt-sized sediment that is formed by the accumulation of wind-blown dust. It covers about 10% of the Earths surface and it is usually homogeneous and highly porous and is traversed by vertical capillaries that permit the sediment to fracture and form vertical bluffs. It was first applied to Rhine River valley loess about 1821, Loess is homogeneous, porous, friable, pale yellow or buff, slightly coherent, typically non-stratified and often calcareous. Loess grains are angular with little polishing or rounding and composed of crystals of quartz, feldspar, mica, Loess can be described as a rich, dust-like soil. Loess deposits may become thick, more than a hundred meters in areas of China. It generally occurs as a deposit that covers areas of hundreds of square kilometers. Loess often stands in either steep or vertical faces, because the grains are angular, loess will often stand in banks for many years without slumping. This soil has a characteristic called vertical cleavage which makes it easily excavated to form cave dwellings, in several areas of the world, loess ridges have formed that are aligned with the prevailing winds during the last glacial maximum. These are called paha ridges in America and greda ridges in Europe, the form of these loess dunes has been explained by a combination of wind and tundra conditions. Loess comes from the German Löss or Löß, and ultimately from Alemannic lösch meaning loose as named by peasants, the term Löß was first described in Central Europe by Karl Cäsar von Leonhard who reported yellowish brown, silty deposits along the Rhine valley near Heidelberg. Charles Lyell brought this term into usage by observing similarities between loess and loess derivatives along the loess bluffs in the Rhine and Mississippi. At that time it was thought that the yellowish brown silt-rich sediment was of fluvial origin being deposited by the large rivers. It wasnt until the end of the 19th century that the origin of loess was recognized. A tremendous number of papers have been published since then, focusing on the formation of loess and on loess/palaeosol sequences as archives of climate and these water conservation works were carried out extensively in China and the research of Loess in China has been continued since 1954. Much effort was put into the setting up of regional and local loess stratigraphies, and Frechen, Horváth & Gábris for the Austrian and Hungarian loess stratigraphy, respectively. During the autumn and winter, when melting of the icesheets and icecaps ceased, as a consequence, large parts of the formerly submerged and unvegetated floodplains of these braided rivers dried out and were exposed to the wind. Because these floodplains consist of sediment containing a high content of glacially ground flour-like silt and clay, they were susceptible to winnowing of their silts. Once entrained by the wind, particles were then deposited downwind, the loess deposits found along both sides of the Mississippi River Alluvial Valley are a classic example of periglacial loess
Loess
–
Loess in
Vicksburg, Mississippi
Loess
–
An
outcrop of loess in
Patagonia
Loess
–
Loess near
Hunyuan,
Shanxi province,
China.
Loess
–
Loess - Balatonfő (Balatonkenese)
24.
Canyon
–
A canyon or gorge is a deep cleft between escarpments or cliffs resulting from the erosive activity of a river over geologic timescales. A canyon may also refer to a rift between two peaks, such as those in ranges including the Rocky Mountains, the Alps. Usually a river or stream and erosion carve out such splits between mountains, examples of mountain-type canyons are Provo Canyon in Utah or Yosemite National Park in Californias Sierra Nevada. Canyons within mountains, or gorges that have an opening on one side are called box canyons. Slot canyons are very narrow canyons, often with smooth walls, steep-sided valleys in the seabed of the continental slope underwater are referred to as submarine canyons. Unlike canyons on land, submarine canyons are thought to be formed by turbidity currents, the word canyon is Spanish in origin, with the same meaning. The word canyon is used in North America while the words gorge and ravine are used in Europe and Oceania, though gorge. In the United States, place names generally use canyon in the southwest and gorge in the northeast, in Canada, a gorge is usually narrow while a ravine is more open and often wooded. The military-derived word defile is occasionally used in the United Kingdom, most canyons were formed by a process of long-time erosion from a plateau or table-land level. The cliffs form because harder rock strata that are resistant to erosion, Canyons are much more common in arid than in wet areas because physical weathering has a more localized effect in arid zones. The wind and water from the combine to erode and cut away less resistant materials such as shales. The freezing and expansion of water also serves to help form canyons, water seeps into cracks between the rocks and freezes, pushing the rocks apart and eventually causing large chunks to break off the canyon walls, in a process known as frost wedging. Canyon walls are formed of resistant sandstones or granite. Sometimes large rivers run through canyons as the result of geological uplift. These are called entrenched rivers, because they are unable to alter their course. In the United States, the Colorado River in the Southwest, Canyons often form in areas of limestone rock. As limestone is soluble to an extent, cave systems form in the rock. When these collapse, a canyon is left, as in the Mendip Hills in Somerset and Yorkshire Dales in Yorkshire, England
Canyon
–
Grand Canyon,
Arizona, at the confluence of the
Colorado and
Little Colorado rivers
Canyon
–
Boğazpınar Canyon,
Mersin Province,
Turkey
Canyon
–
Itaimbezinho Canyon, at
Aparados da Serra National Park,
Brazil
Canyon
–
One of three gorges on
Yangtze river,
China
25.
Arroyo (creek)
–
An arroyo, also called a wash, is a dry creek, stream bed or gulch that temporarily or seasonally fills and flows after sufficient rain. Flash floods are common in arroyos following thunderstorms, in Latin America any small river might be called an arroyo, even if it flows continually all year and is never dry. The Arabic terms rambla or wadi are used in North Africa, arroyos provide a water source to desert animals. The desert dry wash biome is restricted to the arroyos of the southwestern United States, arroyos can be natural fluvial landforms or constructed flood control channels. The term usually applies to a sloped or mountainous terrain in xeric, flash flooding can cause the deep arroyos or deposition of sediment on flooded lands. This can lower the level of the surrounding area, making it unsuitable for agriculture. However a shallow water table lowered in desert arroyo valleys can reduce saline seeping and alkali deposits in the topsoil, research has been conducted in the hydrological modeling relative to arroyos. Natural arroyos are made through the known as arroyo-cutting. This occurs in regions such as New Mexico, where heavy rains can lead to enlargement of rivers cutting into surrounding rock creating ravines which are dry under normal weather conditions. It is argued, however, whether these excessively stormy periods are the cause of arroyo-cutting as other factors such as long-term climate changes must also be taken into account. Arroyo cutting which occurred in the 1900s in the southwestern United States caused serious farming issues such as a water table. In agriculture areas in climates needing irrigation, farmers relied on small constructed arroyos, acequias, zanjas or aqueduct channels. An example of larger constructed arroyos is in Albuquerque, New Mexico, there are several miles of open-air concrete lined drainage channels that drain an area into the main North Diversion Channel, a tributary of the Rio Grande joining upstream of Albuquerque. After the San Juan Project Water Treatment Plant here, the Rio Grandes flow exceeding that needed for the silvery minnow habitat is available for municipal water supply diversion. Signs are posted at the constructed arroyos warning to keep out due to danger of flash flooding, the Arroyo Seco and Los Angeles River are more famous examples in Southern California of former natural arroyo seasonal watercourses that became constructed open drainage system arroyos
Arroyo (creek)
–
Arroyo North Fork of
Las Cruces, New Mexico, looking east.
Arroyo (creek)
–
An arroyo in the
Sonoran Desert of
Arizona
Arroyo (creek)
–
A
flash flood hits a dry streambed in the
Gobi Desert
26.
Sahara
–
The Sahara is the largest hot desert and the third largest desert in the world after Antarctica and the Arctic. Its area of 9,200,000 square kilometres is comparable to the area of the United States. The desert comprises much of North Africa, excluding the fertile region on the Mediterranean Sea coast, the Atlas Mountains of the Maghreb, and the Nile Valley in Egypt and Sudan. It stretches from the Red Sea in the east and the Mediterranean in the north to the Atlantic Ocean in the west, where the landscape gradually changes from desert to coastal plains. To the south, it is bounded by the Sahel, a belt of tropical savanna around the Niger River valley. The Sahara can be divided into several regions including, the western Sahara, the central Ahaggar Mountains, the Tibesti Mountains, the Aïr Mountains, the Ténéré desert, the name Sahara is derived from ṣaḥārā, the plural of the Arabic word for desert. The Sahara covers large parts of Algeria, Chad, Egypt, Libya, Mali, Mauritania, Morocco, Niger, Western Sahara, Sudan and it covers 9 million square kilometres, amounting to 31% of Africa. If all areas with an annual precipitation of less than 250 mm were included. It is one of three physiographic provinces of the African massive physiographic division. The Sahara is mainly rocky hamada, Ergs form only a minor part, wind or rare rainfall shape the desert features, sand dunes, dune fields, sand seas, stone plateaus, gravel plains, dry valleys, dry lakes, and salt flats. Unusual landforms include the Richat Structure in Mauritania, several deeply dissected mountains, many volcanic, rise from the desert, including the Aïr Mountains, Ahaggar Mountains, Saharan Atlas, Tibesti Mountains, Adrar des Iforas, and the Red Sea hills. The highest peak in the Sahara is Emi Koussi, a volcano in the Tibesti range of northern Chad. The central Sahara is hyperarid, with sparse vegetation, the northern and southern reaches of the desert, along with the highlands, have areas of sparse grassland and desert shrub, with trees and taller shrubs in wadis, where moisture collects. In the central, hyperarid region, there are subdivisions of the great desert, Tanezrouft, the Ténéré, the Libyan Desert, the Eastern Desert. These extremely arid areas often receive no rain for years, the northern limit also corresponds to the 100 mm isohyet of annual precipitation. To the south, the Sahara is bounded by the Sahel, the southern limit of the Sahara is indicated botanically by the southern limit of Cornulaca monacantha, or northern limit of Cenchrus biflorus, a grass typical of the Sahel. According to climatic criteria, the limit of the Sahara corresponds to the 150 mm isohyet of annual precipitation. The Sahara is the worlds largest low-latitude hot desert and this steady descending airflow causes a warming and a drying effect in the upper troposphere
Sahara
–
A satellite image of the Sahara by
NASA World Wind.
Sahara
–
Tadrart Acacus desert in western
Libya, part of the Sahara.
Sahara
–
The top image shows the Safsaf Oasis on the surface of the Sahara. The bottom (using
radar) is the rock layer underneath, revealing black channels cut by the meandering of an ancient river that once fed the
oasis.
Sahara
–
A geographical map of Africa, showing the ecological break that defines the Saharan area.
27.
Transhumance
–
Transhumance is a type of nomadism or pastoralism, a seasonal movement of people with their livestock between fixed summer and winter pastures. In montane regions, it implies movement between higher pastures in summer and lower valleys in winter, herders have a permanent home, typically in valleys. Generally only the travel, with a certain number of people necessary to tend them. In contrast, horizontal transhumance is more susceptible to being disrupted by climatic, economic or political change, traditional or fixed transhumance occurs or has occurred throughout the inhabited world, particularly Europe and western Asia. It is often of importance to pastoralist societies, as the dairy products of transhumance flocks. In many languages there are words for the summer pastures. The term transhumance is also used in correlation with nomadic pastoralism – the regular migration of people. The word transhumance comes from French and derives from the Latin words trans across, transhumance developed on every inhabited continent. Although there are cultural and technological variations, the underlying practices for taking advantage of remote seasonal pastures are similar. Transhumance is a form of pastoralism or nomadism, in the Balkans, the Sarakatsani, Aromanian and Yörük peoples traditionally spent summer months in the mountains and returned to lower plains in the winter. When the area was part of the Austro-Hungary and Ottoman empires, in summer, some groups went as far north as the Balkan Mountains, and they would spend the winter on warmer plains in the vicinity of the Aegean Sea. The Morlach were a population of Vlach shepherds who lived in the Dinaric Alps, but as national states appeared in the area of the former Ottoman Empire, new state borders were developed that divided the summer and winter habitats of many of the pastoral groups. These prevented easy movement across borders, particularly at times of war, in most parts of Wales, farm workers and sometimes the farmer would spend the summer months at a hillside summer house, or hafod, where the livestock would graze. During the late autumn the farm family and workers would drive the flocks down to the valleys, both Hafod and Hendref survive in Wales as place names and house names. Today, cattle and sheep that summer on many farms are still transported to lowland winter pastures. In many hilly and mountainous areas of Scotland, agricultural workers spent summer months in bothies or shielings, major drovers roads in the eastern part of Scotland include the Cairnamounth, Elsick Mounth and Causey Mounth. This practice has died out, but was practised within living memory in the Hebridean Islands. Today much transhumance is carried out by truck, with upland flocks being transported under agistment to lower-lying pasture during winter, in southern England, where the climate is mild and the hills low, transhumance historically took the opposite form to more mountainous areas
Transhumance
–
A seter in
Gudbrandsdal, Norway. Above the
tree line in the mountains, it is used as a dwelling for those who accompany livestock to summer pasture.
Transhumance
–
Moving sheep up along a road in the
Massif Central, France
Transhumance
–
Herd of horses on summer mountain pasture in the Pyrenees
Transhumance
–
The summer settlement of the Ğorğoras village in
Çaykara district of
Trabzon province, Turkey
28.
Carboniferous Limestone
–
These rocks formed between 363 and 325 million years ago. Within England and Wales, the entire limestone succession, which includes subordinate mudstones, within Great Britain the suite of rocks known traditionally as the Carboniferous Limestone Series was deposited as marine sediments in three distinct ‘provinces’ separated by contemporary landmasses. One of these landmasses was the Wales-London-Brabant Massif, an east-west aligned belt of land stretching through central Wales and these rocks continue eastwards at depth beneath Oxfordshire. It is characterised by the presence of numerous ‘blocks’ and ‘basins’ each with its own particular depositional style, to the north of the Southern Uplands are the limestones of the Scottish Midland Valley stretching from Ayrshire and Arran in the west to Fife, Lothian and Berwickshire in the east. Though of Carboniferous age, the limestones of this Scottish province are not assigned to the Carboniferous Limestone Supergroup, the Carboniferous Limestone is widespread throughout Ireland. The Carboniferous Limestone is a significant landscape-forming rock unit in each of the provinces of Great Britain within which it is found. It forms prominent headlands such as those of Stackpole Head and Lydstep Point and it is here referred to as the ‘north crop’ as distinct from a sub-parallel outcrop, the ‘south crop’ which defines the southern rim of the South Wales Coalfield. The outcrop continues through Ystradfellte to Pontneddfechan, Penderyn and Pontsticill and it then runs near the southern margin of the national park via Trefil and the Llangattock escarpment to Blorenge where it turns southwards. A very narrow ‘east crop’ and ‘south crop’ run by Cwmbran and it turns west again to meet Swansea Bay at Porthcawl. West of the bay, the forms the renowned southern coast of Gower between Mumbles Head and Worms Head. There are further occurrences in the Vale of Glamorgan, both inland and on the coast, an important outlier is that of the Forest of Dean basin which forms the cliffs of the Wye Valley, straddling the England/Wales border and extends southwestwards through Chepstow to Undy. The larger part of the Mendip Hills are formed from Carboniferous Limestone, showing notable geomorphological features, including Cheddar Gorge, Burrington Combe, the Avon Gorge west of Bristol and the coastal cliffs at Clevedon and Weston-super-Mare are cut in this rock. The limestone islands of Flat Holm and Steep Holm are prominent in views across the mouth of the Severn Estuary, there are limited outcrops on the Isle of Man and more extensive ones in Anglesey notably along the Menai Strait, around Benllech and towards Puffin Island. The Carboniferous Limestone belt extends eastwards to from the Great Orme at Llandudno, the neighbouring Little Orme, there are a few outcrops in Shropshire such as Titterstone Clee Hill and at Little Wenlock. The White Peak is named for the limestone which characterises the heart of the Peak District and through deep gorges have been cut by rivers such as the Wye, Dove. The limestone is concealed beneath younger rocks to the east and west, to the north the limestone is exposed once again in east Lancashire and in the Yorkshire Dales. An outcrop extends from Kirkby Stephen along the side of the Vale of Eden. North again, it is a major landscape forming feature in the North Pennines, there are scattered outcrops along the north coast of the Solway Firth
Carboniferous Limestone
–
Carboniferous Limestone exposed at
Ogmore-by-Sea, Wales. Carboniferous/Jurassic unconformity.
Carboniferous Limestone
–
Carboniferous Limestone exposed at
Tedbury Camp, Somerset, England.
Carboniferous Limestone
–
Cross-section of Carboniferous Limestone bored by Jurassic organisms; borings include
Gastrochaenolites (some with boring
bivalves in place) and
Trypanites;
Mendip Hills, England; scale bar = 1 cm.
Carboniferous Limestone
–
Carboniferous coral, Ingleton.
29.
Velocity
–
The velocity of an object is the rate of change of its position with respect to a frame of reference, and is a function of time. Velocity is equivalent to a specification of its speed and direction of motion, Velocity is an important concept in kinematics, the branch of classical mechanics that describes the motion of bodies. Velocity is a vector quantity, both magnitude and direction are needed to define it. The scalar absolute value of velocity is called speed, being a coherent derived unit whose quantity is measured in the SI system as metres per second or as the SI base unit of. For example,5 metres per second is a scalar, whereas 5 metres per second east is a vector, if there is a change in speed, direction or both, then the object has a changing velocity and is said to be undergoing an acceleration. To have a constant velocity, an object must have a constant speed in a constant direction, constant direction constrains the object to motion in a straight path thus, a constant velocity means motion in a straight line at a constant speed. For example, a car moving at a constant 20 kilometres per hour in a path has a constant speed. Hence, the car is considered to be undergoing an acceleration, Speed describes only how fast an object is moving, whereas velocity gives both how fast and in what direction the object is moving. If a car is said to travel at 60 km/h, its speed has been specified, however, if the car is said to move at 60 km/h to the north, its velocity has now been specified. The big difference can be noticed when we consider movement around a circle and this is because the average velocity is calculated by only considering the displacement between the starting and the end points while the average speed considers only the total distance traveled. Velocity is defined as the rate of change of position with respect to time, average velocity can be calculated as, v ¯ = Δ x Δ t. The average velocity is less than or equal to the average speed of an object. This can be seen by realizing that while distance is always strictly increasing, from this derivative equation, in the one-dimensional case it can be seen that the area under a velocity vs. time is the displacement, x. In calculus terms, the integral of the velocity v is the displacement function x. In the figure, this corresponds to the area under the curve labeled s. Since the derivative of the position with respect to time gives the change in position divided by the change in time, although velocity is defined as the rate of change of position, it is often common to start with an expression for an objects acceleration. As seen by the three green tangent lines in the figure, an objects instantaneous acceleration at a point in time is the slope of the tangent to the curve of a v graph at that point. In other words, acceleration is defined as the derivative of velocity with respect to time, from there, we can obtain an expression for velocity as the area under an a acceleration vs. time graph
Velocity
–
As a change of direction occurs while the cars turn on the curved track, their velocity is not constant.
30.
Eolianite
–
Eolianite or aeolianite is any rock formed by the lithification of sediment deposited by aeolian processes, that is, the wind. It is also known as kurkar in the Middle East, miliolite in India and Arabia, eolianite occurs in many parts of the world. It occurs most extensively between the latitudes of 20° and 40° in both hemispheres, with little nearer the equator, and virtually no deposits nearer the poles. There is no apparent difference in distribution between the hemispheres, but if the extent and thickness of deposits are taken into account, on the west coast, there are over 800 kilometres of eolianite cliffs, which are over 150 metres thick in some places. These cliffs, locally known as the Tamala Limestone Formation, contain layers of dune origin interspersed with layers of shallow-marine origin. Other substantial deposits occur in Bermuda, the Bahamas, the southern and eastern coasts of South Africa, the Mediterranean, India, and oceanic islands of the Pacific, Atlantic, Sedimentary rock Facies Sedimentary depositional environment Brooke, Brendan
Eolianite
–
Holocene eolianite on
Long Island, Bahamas.
Eolianite
–
Eolianite outcrop at Aikerness on the island of
Orkney, Scotland
31.
Alluvial desert
–
A desert pavement, also called reg, serir, gibber, or saï is a desert surface covered with closely packed, interlocking angular or rounded rock fragments of pebble and cobble size. Desert varnish collects on the surface rocks over time. Geologists debate the mechanics of pavement formation and their age, several theories have been proposed for the formation of desert pavements. A common theory suggests they form through the removal of sand, dust and other fine-grained material by the wind and intermittent rain. The removal of particles by wind does not continue indefinitely, because once the pavement forms. The small particles collect underneath the pavement surface, forming a vesicular A soil horizon, a newer theory of pavement formation comes from studies of places such as Cima Dome, in the Mojave Desert of California, by Stephen Wells and his coworkers. At Cima Dome, geologically recent lava flows are covered by younger layers, with desert pavement on top of them. The soil has built up, not blown away, yet the stones remain on top. There are no stones in the soil, not even gravel, researchers can determine how many years a stone has been exposed on the ground. Wells used a method based on cosmogenic helium-3, which forms by cosmic ray bombardment at the ground surface, helium-3 is retained inside grains of olivine and pyroxene in the lava flows, building up with exposure time. The helium-3 dates show that the stones in the desert pavement at Cima Dome have all been at the surface the same amount of time as the solid lava flows right next to them. He wrote in a July 1995 article in Geology, that he concluded, while the stones remain on the surface due to heave, deposition of windblown dust must build up the soil beneath that pavement. For the geologist, this means that some desert pavements preserve a long history of dust deposition beneath them. The dust is a record of ancient climate, just as it is on the sea floor. Desert pavement surfaces are coated with desert varnish, a dark brown. In the USA a famous example can be found on Newspaper Rock in southeastern Utah, Desert varnish is a thin coating of manganese, iron and clays on the surface of sun-baked boulders. It is formed by colonies of bacteria living on the surface for thousands of years. Desert varnish is also prevalent in the Mojave desert and Great Basin geomorphic province, stony deserts may be known by different names according to the region
Alluvial desert
–
Desert pavement, showing
desert varnish on the pebbles.
Gibber plains of Central Australia
Alluvial desert
–
The desert known as Reg de l'
Adrar in
Mauritania
32.
Coulee
–
Coulee is applied rather loosely to different landforms, all of which refer to a kind of valley or drainage zone. The word coulee comes from the Canadian French coulée, from the French word couler meaning to flow, the term is often used interchangeably in the Great Plains for any number of water features, from ponds to creeks. In southern Louisiana the word originally meant a gully or ravine usually dry or intermittent. As stream channels were dredged or canalized, the term was applied to perennial streams. The term is used for small ditches or canals in the swamp. The dry, braided channels formed by glacial drainage of the Scablands of eastern Washington, such as Grand Coulee, the furrowed moraines channeling rain runoff in the area east of the Coteau du Missouri in the western United States and western Canada at the base of the Rocky Mountains. In the western United States, tongue-like protrusions of solidified lava, in Wisconsin, it is applied to valleys. These valleys tend to have high, steep walls, hollow is used as a synonym, often for the smallest of such valleys. The term is applied to the greater La Crosse, Wisconsin metropolitan area. The Gassman Coulee Trestle supports commercial and Amtrak trains, SW of Minot ND, the coulee may have been a contributing factor to the flooding of the Souris River in June 2011. In some parts of Louisiana coulees are not concreted but rather sheer sided large ditches that collect smaller ditch runoff, aside from those formed by volcanic eruptions, they are commonly canyons characterized by steep walls that have been shaped by erosion. These types of coulees are generally found in the northwestern United States, in the American west, rapid melting of glaciers at the end of the last ice age caused catastrophic flooding which removed bedrock by massive down-cutting erosion, forming deep canyons. Some coulees may be dry or contain small streams, however these small streams do not have the magnitude of force necessary to form such expansive erosion. In Wisconsin, they are the product of nearly a million years of erosion. The loose rocks at the base of the wall form what are called scree slopes and these are formed when chunks of the canyon wall give way in a rockslide. Left alone, the valleys are often woodland, with the ridgetops transitioning into tallgrass prairie when not turned into pasture or used for row crops, coulees provide shelter from wind and concentrated water supplies to plants which would otherwise struggle to survive in the xeric sagebrush steppe. Trees are often found in habitats along streams in coulees
Coulee
–
An upwards view of section of the wall protruding to the canyon. There is a marsh in the foreground.
Coulee
–
A view through a coulee, with steep but lower sides, and water in the bottom.
Coulee
–
Drumheller Channels in the
Columbia Basin of
Washington
Coulee
–
A view upward into a coulee in the
Oldman River valley in
Lethbridge,
Alberta
33.
Gully
–
A gully is a landform created by running water, eroding sharply into soil, typically on a hillside. Gullies resemble large ditches or small valleys, but are metres to tens of metres in depth and width, when the gully formation is in process, the water flow rate can be substantial, causing a significant deep cutting action into soil. The earliest known usage of the term is from 1657 and it originates from the French word goulet, a diminutive form of goule which means throat. It is possible that the term was derived from a type of knife at the time, gullying or gully erosion is the process by which gullies are formed. Hillsides are more prone to gullying when they are cleared of vegetation, through deforestation, the eroded soil is easily carried by the flowing water after being dislodged from the ground, normally when rainfall falls during short, intense storms such as during thunderstorms. A gully may grow in length by means of erosion at a knick point. This erosion can result from interflow as well as surface runoff, gullies reduce the productivity of farmland where they incise into the land, and produce sediment that may clog downstream waterbodies. Because of this, much effort is invested into the study of gullies within the scope of geomorphology, in the prevention of gully erosion, the total soil loss from gully formation and subsequent downstream river sedimentation can be sizeable. Gullies can be formed or enlarged by a number of human activities, artificial gullies are formed during hydraulic mining when jets or streams of water are projected onto soft alluvial deposits to extract gold or tin ore. The remains of mining methods are very visible landform features in old goldfields such as in California. The badlands at Las Medulas for example, were created during the Roman period by hushing or hydraulic mining of the gold-rich alluvium with water supplied by numerous aqueducts tapping nearby rivers, each aqueduct produced large gullies below by erosion of the soft deposits. The effluvium was carefully washed with smaller streams of water to extract the nuggets, gullies are widespread at mid- to high latitudes on the surface of Mars, and are some of the youngest features observed on that planet, probably forming within the last few 100,000 years. Flow as springs from deeper seated liquid water aquifers in the subsurface is also a possible explanation for the formation of some Martian gullies. Arroyo Coulee Couloir Canyon Gulch Ravine Wadi Lavaka Badlands Rill Oxford English Dictionary
Gully
–
A gully in
Saratov Oblast,
Russia.
Gully
–
A gully in
Kharkov oblast,
Ukraine.
Gully
–
Voçoroca (Portuguese for gully) in
Avaré,
Brasil
34.
Oasis
–
In geography, an oasis is an isolated area of vegetation in a desert, typically surrounding a spring or similar water source, such as a pond or small lake. Oases also provide habitat for animals and even if the area is big enough. The location of oases has been of importance for trade and transportation routes in desert areas, caravans must travel via oases so that supplies of water. Thus, political or military control of an oasis has in many cases meant control of trade on a particular route. For example, the oases of Awjila, Ghadames, and Kufra, oases are formed from underground rivers or aquifers such as an artesian aquifer, where water can reach the surface naturally by pressure or by man-made wells. Occasional brief thunderstorms provide subterranean water to sustain natural oases, such as the Tuat, substrata of impermeable rock and stone can trap water and retain it in pockets, or on long faulting subsurface ridges or volcanic dikes water can collect and percolate to the surface. Any incidence of water is used by migrating birds, which also pass seeds with their droppings which will grow at the waters edge forming an oasis. It can also be used to plant crops, the word oasis came into English via Latin, oasis from Ancient Greek, ὄασις óasis, which in turn is a direct borrowing from Demotic Egyptian. The word for oasis in the later attested Coptic language is wahe or ouahe which means a dwelling place, people who live in an oasis must manage land and water use carefully, fields must be irrigated to grow plants like apricots, dates, figs, and olives. The most important plant in an oasis is the date palm and these palm trees provide shade for smaller trees like peach trees, which form the middle layer. By growing plants in different layers, the farmers make best use of the soil, many vegetables are also grown and some cereals, such as barley, millet, and wheat, are grown where there is more moisture. Great Man-Made River – the worlds largest irrigation project, developed in Libya to connect cities with fossil water. Guelta Mirage Oasification Qanat Wadi Water supply référence, Jardins au désert |Battesti, Jardins au désert, Evolution des pratiques et savoirs oasiens, Jérid tunisien, Paris, Éditions IRD, coll. À travers champs,2005,440 p. ISBN 2-7099-1564-2 Open Archives, book in free access / in French The dictionary definition of oasis at Wiktionary
Oasis
–
Oasis in the
Libyan part of the
Sahara Desert
Oasis
–
Taghit,
Algeria
Oasis
–
Ein Gedi,
Israel
Oasis
–
Fish Springs National Wildlife Refuge,
Utah.
35.
UNESCO
–
The United Nations Educational, Scientific and Cultural Organization is a specialized agency of the United Nations based in Paris. It is the heir of the League of Nations International Committee on Intellectual Cooperation, UNESCO has 195 member states and nine associate members. Most of its offices are cluster offices covering three or more countries, national and regional offices also exist. UNESCO pursues its objectives through five major programs, education, natural sciences, social/human sciences, culture and it is also a member of the United Nations Development Group. UNESCO and its mandate for international cooperation can be traced back to a League of Nations resolution on 21 September 1921, on 18 December 1925, the International Bureau of Education began work as a non-governmental organization in the service of international educational development. However, the work of predecessor organizations was largely interrupted by the onset of World War II. On 30 October 1943, the necessity for an organization was expressed in the Moscow Declaration, agreed upon by China, the United Kingdom, the United States. This was followed by the Dumbarton Oaks Conference proposals of 9 October 1944, a prominent figure in the initiative for UNESCO was Rab Butler, the Minister of Education for the United Kingdom. At the ECO/CONF, the Constitution of UNESCO was introduced and signed by 37 countries, the Preparatory Commission operated between 16 November 1945, and 4 November 1946—the date when UNESCOs Constitution came into force with the deposit of the twentieth ratification by a member state. The first General Conference took place between 19 November to 10 December 1946, and elected Dr. Julian Huxley to Director-General and this change in governance distinguished UNESCO from its predecessor, the CICI, in how member states would work together in the organizations fields of competence. In 1956, the Republic of South Africa withdrew from UNESCO claiming that some of the organizations publications amounted to interference in the racial problems. South Africa rejoined the organization in 1994 under the leadership of Nelson Mandela, UNESCOs early work in the field of education included the pilot project on fundamental education in the Marbial Valley, Haiti, started in 1947. This project was followed by missions to other countries, including, for example. In 1948, UNESCO recommended that Member States should make free primary education compulsory, in 1990, the World Conference on Education for All, in Jomtien, Thailand, launched a global movement to provide basic education for all children, youths and adults. Ten years later, the 2000 World Education Forum held in Dakar, Senegal, UNESCOs early activities in culture included, for example, the Nubia Campaign, launched in 1960. The purpose of the campaign was to move the Great Temple of Abu Simbel to keep it from being swamped by the Nile after construction of the Aswan Dam, during the 20-year campaign,22 monuments and architectural complexes were relocated. This was the first and largest in a series of campaigns including Mohenjo-daro, Fes, Kathmandu, Borobudur, the organizations work on heritage led to the adoption, in 1972, of the Convention concerning the Protection of the World Cultural and Natural Heritage. The World Heritage Committee was established in 1976 and the first sites inscribed on the World Heritage List in 1978, since then important legal instruments on cultural heritage and diversity have been adopted by UNESCO member states in 2003 and 2005
UNESCO
–
UNESCO offices in
Brasília
UNESCO
–
UNESCO
UNESCO
–
UNESCO Institute for Water Education in
Delft
UNESCO
–
The Garden of Peace, UNESCO headquarters, Paris. Donated by the Government of Japan, this garden was designed by American-Japanese sculptor artist Isamu Noguchi in 1958 and installed by Japanese gardener Toemon Sano.
36.
Drainage basin
–
A drainage basin or catchment area is any area of land where precipitation collects and drains off into a common outlet, such as into a river, bay, or other body of water. Drainage basins connect into other drainage basins at elevations in a hierarchical pattern, with smaller sub-drainage basins. Other terms used to describe drainage basins are catchment, catchment basin, drainage area, river basin and water basin. In closed drainage basins the water converges to a point inside the basin, known as a sink, which may be a permanent lake. The drainage basin acts as a funnel by collecting all the water within the covered by the basin. Each drainage basin is separated topographically from adjacent basins by a perimeter, drainage basins are similar but not identical to hydrologic units, which are drainage areas delineated so as to nest into a multi-level hierarchical drainage system. Hydrologic units are defined to allow multiple inlets, outlets, or sinks, in a strict sense, all drainage basins are hydrologic units but not all hydrologic units are drainage basins. Drainage basins of the oceans and seas of the world. Grey areas are endorheic basins that do not drain to the oceans, the following is a list of the major ocean basins, About 48. 7% of the worlds land drains to the Atlantic Ocean. The two major mediterranean seas of the world also flow to the Atlantic, The Caribbean Sea and Gulf of Mexico basin includes most of the U. S. The Mediterranean Sea basin includes much of North Africa, east-central Africa, Southern, Central, and Eastern Europe, Turkey, and the areas of Israel, Lebanon. Just over 13% of the land in the world drains to the Pacific Ocean, the Indian Oceans drainage basin also comprises about 13% of Earths land. It drains the eastern coast of Africa, the coasts of the Red Sea and the Persian Gulf, the Indian subcontinent, Burma, antarctica comprises approximately eight percent of the Earths land. The five largest river basins, from largest to smallest, are the basins of the Amazon, the Río de la Plata, the Congo, the Nile, and the Mississippi. The three rivers that drain the most water, from most to least, are the Amazon, Ganga, endorheic drainage basins are inland basins that do not drain to an ocean. Around 18% of all land drains to endorheic lakes or seas or sinks, the largest of these consists of much of the interior of Asia, which drains into the Caspian Sea, the Aral Sea, and numerous smaller lakes. Some of these, such as the Great Basin, are not single drainage basins but collections of separate, in endorheic bodies of standing water where evaporation is the primary means of water loss, the water is typically more saline than the oceans. An extreme example of this is the Dead Sea, drainage basins have been historically important for determining territorial boundaries, particularly in regions where trade by water has been important
Drainage basin
–
Animation of
Latoriţa River drainage basin,
Romania
Drainage basin
–
Example of a drainage basin. The dashed line is the main water divide of the hydrographic basin.
Drainage basin
–
Endorheic basin in
Central Asia
Drainage basin
–
The
Mississippi River drains the largest area of any
U.S. river, much of it
agricultural regions. Agricultural runoff and other water pollution that flows to the outlet is the cause of the
hypoxic, or dead zone in the
Gulf of Mexico.
37.
Drainage system (geomorphology)
–
In geomorphology, drainage systems, also known as river systems, are the patterns formed by the streams, rivers, and lakes in a particular drainage basin. They are governed by the topography of the land, whether a region is dominated by hard or soft rocks. Geomorphologists and hydrologists often view streams as being part of drainage basins, a drainage basin is the topographic region from which a stream receives runoff, throughflow, and groundwater flow. The number, size, and shape of the drainage basins found in an area vary and the larger the topographic map, according to the configuration of the channels, drainage systems can fall into one of several categories known as drainage patterns. Drainage patterns depend on the topography and geology of the land, a drainage system is described as accordant if its pattern correlates to the structure and relief of the landscape over which it flows. Dendritic drainage systems are the most common form of drainage system, in a dendritic system, there are many contributing streams, which are then joined together into the tributaries of the main river. They develop where the channel follows the slope of the terrain. Dendritic systems form in V-shaped valleys, as a result, the types must be impervious and non-porous. A parallel drainage system is a pattern of rivers caused by slopes with some relief. Because of the slopes, the streams are swift and straight, with very few tributaries. This system forms on uniformly sloping surfaces, for example, rivers flowing southeast from the Aberdare Mountains in Kenya, parallel drainage patterns form where there is a pronounced slope to the surface. A parallel pattern also develops in regions of parallel, elongate landforms like outcropping resistant rock bands, tributary streams tend to stretch out in a parallel-like fashion following the slope of the surface. A parallel pattern sometimes indicates the presence of a fault that cuts across an area of steeply folded bedrock. All forms of transitions can occur between parallel, dendritic, and trellis patterns, the geometry of a trellis drainage system is similar to that of a common garden trellis used to grow vines. As the river flows along a valley, smaller tributaries feed into it from the steep slopes on the sides of mountains. These tributaries enter the river at approximately 90 degree angle. Trellis drainage is characteristic of folded mountains, such as the Appalachian Mountains in North America, rectangular drainage develops on rocks that are of approximately uniform resistance to erosion, but which have two directions of joining at approximately right angles. The joints are less resistant to erosion than the bulk rock so erosion tends to preferentially open the joints
Drainage system (geomorphology)
–
Dendritic drainage: the
Yarlung Tsangpo River, Tibet, seen from space: snow cover has melted in the valley system.
Drainage system (geomorphology)
–
Dendritic drainage pattern
Drainage system (geomorphology)
–
Parallel drainage pattern
Drainage system (geomorphology)
–
Trellis drainage pattern
38.
Estuary
–
An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a zone between river environments and maritime environments. They are subject both to marine influences—such as tides, waves, and the influx of saline water—and to riverine influences—such as flows of fresh water and sediment. The inflows of sea water and fresh water provide high levels of nutrients both in the water column and in sediment, making estuaries among the most productive natural habitats in the world. Most existing estuaries formed during the Holocene epoch with the flooding of river-eroded or glacially scoured valleys when the sea began to rise about 10. Estuaries are typically classified according to their geomorphological features or to water-circulation patterns, the banks of many estuaries are amongst the most heavily populated areas of the world, with about 60% of the worlds population living along estuaries and the coast. The word estuary is derived from the Latin word aestuarium meaning tidal inlet of the sea, there have been many definitions proposed to describe an estuary. However, this definition excludes a number of water bodies such as coastal lagoons. This broad definition also includes fjords, lagoons, river mouths, an estuary is a dynamic ecosystem having a connection to the open sea through which the sea water enters with the rhythm of the tides. The sea water entering the estuary is diluted by the water flowing from rivers. The pattern of dilution varies between different estuaries and depends on the volume of water, the tidal range. Drowned river valleys are known as coastal plain estuaries. In places where the sea level is rising relative to the land, sea water progressively penetrates into river valleys and this is the most common type of estuary in temperate climates. Well-studied estuaries include the Severn Estuary in the United Kingdom and the Ems Dollard along the Dutch-German border, the width-to-depth ratio of these estuaries is typically large, appearing wedge-shaped in the inner part and broadening and deepening seaward. Water depths rarely exceed 30 m, examples of this type of estuary in the U. S. are the Hudson River, Chesapeake Bay, and Delaware Bay along the Mid-Atlantic coast, and Galveston Bay and Tampa Bay along the Gulf Coast. They are relatively common in tropical and subtropical locations and these estuaries are semi-isolated from ocean waters by barrier beaches. Formation of barrier beaches partially encloses the estuary, with only narrow inlets allowing contact with the ocean waters, bar-built estuaries typically develop on gently sloping plains located along tectonically stable edges of continents and marginal sea coasts. They are extensive along the Atlantic and Gulf coasts of the U. S. in areas with active coastal deposition of sediments, barrier beaches form in shallow water and are generally parallel to the shoreline, resulting in long, narrow estuaries
Estuary
–
Estuary of the
Klamath River in
Northern California
Estuary
–
River Exe estuary
Estuary
–
River Nith estuary
Estuary
–
Estuary mouth located in
Darwin,
Northern Territory,
Australia
39.
Strahler number
–
In mathematics, the Strahler number or Horton–Strahler number of a mathematical tree is a numerical measure of its branching complexity. Alternative stream ordering systems have developed by Shreve and Hodgkinson et al. The degree of a node in a tree is just its number of children, one may assign a Strahler number to all nodes of a tree, in bottom-up order, as follows, If the node is a leaf, its Strahler number is one. If the node has one child with Strahler number i, and all children have Strahler numbers less than i. If the node has two or more children with Strahler number i, and no children with greater number, then the Strahler number of the node is i +1, the Strahler number of a tree is the number of its root node. Algorithmically, these numbers may be assigned by performing a depth-first search and assigning each nodes number in postorder. Any node with Strahler number i must have at least two descendants with Strahler number i −1, at least four descendants with Strahler number i −2, etc. and at least 2i −1 leaf descendants. Therefore, in a tree with n nodes, the largest possible Strahler number is log2 n +1, however, unless the tree forms a complete binary tree its Strahler number will be less than this bound. In an n-node binary tree, chosen uniformly at random among all possible binary trees, the expected index of the root is with high probability very close to log4 n. In the application of the Strahler stream order to hydrology, each segment of a stream or river within a network is treated as a node in a tree. When two first-order streams come together, they form a second-order stream, when two second-order streams come together, they form a third-order stream. Streams of lower order joining a higher order stream do not change the order of the higher stream, thus, if a first-order stream joins a second-order stream, it remains a second-order stream. It is not until a second-order stream combines with another stream that it becomes a third-order stream. As with mathematical trees, a segment with index i must be fed by at least 2i −1 different tributaries of index 1, Shreve noted that Horton’s and Strahler’s Laws should be expected from any topologically random distribution. To qualify as a stream a hydrological feature must be either recurring or perennial, recurring streams have water in the channel for at least part of the year. The index of a stream or river may range from 1 to 12, the Ohio River is of order eight and the Mississippi River is of order 10. Estimates are that 80% of the streams on the planet are first to third order headwater streams, the bifurcation ratio can also show which parts of a drainage basin are more likely to flood, comparatively, by looking at the separate ratios. Most British rivers have a ratio of between 3 and 5
Strahler number
–
Diagram showing the Strahler stream order
40.
River delta
–
A river delta is a landform that forms from deposition of sediment carried by a river as the flow leaves its mouth and enters slower-moving or standing water. This occurs where a river enters an ocean, sea, estuary, lake, reservoir, River deltas are ecologically important as they provide coastline defense, are home to many species, and can impact drinking water supply. The tidal currents also cannot be too strong, as sediment would wash out into the body faster than the river deposits it. Of course, the river must carry enough sediment to layer into deltas over time, the rivers velocity decreases rapidly, causing it to deposit the majority, if not all, of its load. This alluvium builds up to form the river delta, when the flow enters the standing water, it is no longer confined to its channel and expands in width. This flow expansion results in a decrease in the flow velocity, as a result, sediment drops out of the flow and deposits. Over time, this single channel builds a deltaic lobe, pushing its mouth into the standing water, as the deltaic lobe advances, the gradient of the river channel becomes lower because the river channel is longer but has the same change in elevation. As the slope of the channel decreases, it becomes unstable for two reasons. First, gravity makes the flow in the most direct course down slope. If the river breaches its natural levees, it out onto a new course with a shorter route to the ocean. Second, as its slope gets lower, the amount of stress on the bed decreases, which results in deposition of sediment within the channel. This makes it easier for the river to breach its levees, often when the channel does this, some of its flow remains in the abandoned channel. When these channel-switching events occur, a mature delta develops a distributary network, another way these distributary networks form is from deposition of mouth bars. When this mid-channel bar is deposited at the mouth of a river and this results in additional deposition on the upstream end of the mouth-bar, which splits the river into two distributary channels. A good example of the result of this process is the Wax Lake Delta, in both of these cases, depositional processes force redistribution of deposition from areas of high deposition to areas of low deposition. This results in the smoothing of the shape of the delta as the channels move across its surface. Because the sediment is laid down in fashion, the shape of these deltas approximates a fan. The more often the flow changes course, the shape develops as closer to an ideal fan, the Mississippi and Ural River deltas, with their birds-feet, are examples of rivers that do not avulse often enough to form a symmetrical fan shape
River delta
–
Sacramento Delta at flood stage, early 2009.
River delta
–
Lower Mississippi River land loss over time
River delta
–
Delta lobe switching in the
Mississippi Delta, 4600 yrs
BP, 3500 yrs BP, 2800 yrs BP, 1000 yrs BP, 300 yrs BP, 500 yrs BP, current
River delta
–
The
Ganges Delta in
India and
Bangladesh is the largest delta in the world and it is also one of the most fertile regions in the world.
41.
River sinuosity
–
This dimensionless quantity can also be rephrased as the actual path length divided by the shortest path length of a curve. The value ranges from 1 to infinity or for an actual path. The curve must be continuous between the two ends, the sinuosity value is really significant when the line is continuously differentiable. The distance between both ends can also be evaluated by a plurality of segments according to a line passing through the successive inflection points. The calculation of the sinuosity is valid in a 3-dimensional space, nevertheless, it is possible to see a very strong sinuosity in the succession of few river bends, or of laces on some mountain roads. The sinuosity S of,2 inverted continuous semicircles located in the plane is S = π2 ≈1.5708. It is independent of the radius, a sine function. The sinuosity index can be explained, then, as the deviations from a path defined by the direction of maximum downslope. For this reason, bedrock streams that flow directly downslope have a sinuosity index of 1, and meandering streams have a sinuosity index that is greater than 1. For rivers, the classes of sinuosity, SI, are, SI <1.05, almost straight 1.05 ≤ SI <1.25, winding 1.25 ≤ SI <1.50
River sinuosity
–
Laces on mountain road with high sinuosity at
Luz Ardiden
River sinuosity
–
Calculation of sinuosity for an oscillating curve.
River sinuosity
–
The meandering
Rio Cauto at Guamo Embarcadero,
Cuba, is not taking the shortest path downslope. Therefore, its sinuosity index is > 1.
River sinuosity
–
Two ski tracks with different degrees of sinuosity on the same slope
42.
Anabranch
–
An anabranch is a section of a river or stream that diverts from the main channel or stem of the watercourse and rejoins the main stem downstream. Local anabranches can be the result of small islands in the watercourse, in larger anabranches, the flow can diverge for a distance of several kilometers before rejoining the main channel. The term anabranch, in its meaning, is used more frequently in Australia than in the rest of the English-speaking world. The term anabranching river describes a river with many anabranches, whilst an anastomosing river is a subset of this river type. A distributary is a branch of a river that does not rejoin the main channel, a bayou is often an anabranch. The Magdalena River, in Colombia, bifurcates in El Banco in two branches, Brazo de Loba and Brazo de Mompox, the first one, Brazo de Loba is the main navigable channel and is 177 km long. Brazo de Mompox is thus the anabranch, there are several other branches that join those two main branches, interconnected by swamps, the main ones being Quitasol, Chicagua and La Victoria. Between Brazo de Loba and Brazo de Mompox is the island of Mompox or Margarita Island, in the Fraser River delta of British Columbia, Canada, North Arm Fraser River, Middle Arm Fraser River, and South Arm Fraser River each fall into Georgia Strait separately. On the other hand, Annacis Island splits Fraser River into the Annieville Channel and the Annacis Channel, in western New South Wales the Great Darling Anabranch is the ancestral path of the Darling River, dividing south of Menindee and extending for 460 km before joining the Murray River. The anabranch contains flowing water only in wetter years, in the Lower Simpson Desert, in South Australia, Kallakoopah Creek is an anabranch of the Warburton River that flows during major Warburton floods of over 5 m in depth. The Bahr el Zeraf in southern Sudan splits from the Bahr al Jabal section of the White Nile and flows for 240 km, approximately 15 km out of Charters Towers is a section of the Burdekin River known as the anabranch. This strip of water is separate from the main flood way, once there is consistent rain, it will meet up with the river again and flood with fresh water. It is well known for barramundi fishing
Anabranch
–
Anabranches at the junction of the
Yukon River and the
Koyukuk River in
Alaska, August 24, 1941.
43.
Avulsion (river)
–
In sedimentary geology and fluvial geomorphology, avulsion is the rapid abandonment of a river channel and the formation of a new river channel. Avulsions occur as a result of channel slopes that are less steep than the slope that the river could travel if it took a new course. Avulsions are common in river deltas, where sediment deposits as the river enters the ocean and this process is also known as delta switching. Deposition from the results in the formation of an individual deltaic lobe that pushes out into the sea. An example of a deltaic lobe is the delta of the Mississippi River. As the deltaic lobe advances, the slope of the channel becomes lower because the river channel is longer but has the same change in elevation. As the slope of the channel decreases, it becomes unstable for two reasons. First, water under the force of gravity will tend to flow in the most direct course downslope, if the river could breach its natural levees, it would spill out onto a new course with a shorter route to the ocean, thereby obtaining a more stable steeper slope. This will make it easier for the river to breach its levees, when this avulsion occurs, the new channel carries sediment out to the ocean, building a new deltaic lobe. This process is related to the distributary network of river channels that can be observed within a river delta. When the channel does this, some of its flow can remain in the abandoned channel, when these channel switching events happen repeatedly over time, a mature delta will gain a distributary network. Subsidence of the delta and/or sea-level rise can further cause backwater and this deposition fills the channels and leaves a geologic record of channel avulsion in sedimentary basins. On average, an avulsion will occur every time the bed of a river channel aggrades enough that the channel is superelevated above the floodplain by one channel-depth. In this situation, enough hydraulic head is available that any breach of the levees will result in an avulsion. Rivers can also avulse due to the erosion of a new channel that creates a path through the landscape. This can happen during large floods in situations in which the slope of the new channel is significantly greater than that of the old channel. Where the new channels slope is about the same as the old channels slope, an example of an erosional avulsion is the 2006 avulsion of the Suncook River in New Hampshire, in which heavy rains caused flow levels to rise. An example of an avulsion is known as a meander cutoff
Avulsion (river)
–
Plumes of
sediment enter the
ocean from several
mouths of the
Mississippi River bird's-foot delta. This sediment is responsible for building the
delta and allowing it to advance into the sea. As it extends further offshore, the channel slope will decrease and its bed will
aggrade, promoting an avulsion.
Avulsion (river)
44.
Bar (river morphology)
–
A bar in a river is an elevated region of sediment that has been deposited by the flow. Types of bars include mid-channel bars, point bars, and mouth bars, bars are typically found in the slowest moving, shallowest parts of rivers and streams, and are often parallel to the shore and occupy the area farthest from the thalweg. The locations of bars are determined by the geometry of the river, point bars form on the inside of meander bends in meandering rivers because the shallow flow and low shear stresses there reduce the amount of material that can be carried there. The excess material out of transport and forms the bar. Pendant bar River island John Bridge and Robert Demicco, earth Surface Processes, Landforms and Sediment Deposits
Bar (river morphology)
–
Point bar at a river meander: the Cirque de la Madeleine in the
Gorges de l'Ardèche, France.
Bar (river morphology)
–
Gravel bar in the
American River,
Washington,
USA.
45.
Braided river
–
Not to be confused with the River Braid, Ballymena, Northern Ireland. Braided streams occur in rivers with high slope and/or large sediment load, braided channels are also typical of environments that dramatically decrease channel depth, and consequently channel velocity, such as river deltas, alluvial fans and peneplains. Braided rivers, as distinct from meandering rivers, occur when a level of sediment load or slope is reached whilst a steep gradient is also maintained. A threshold slope was experimentally determined to be 0.016 for a 0.15 cu ft/s stream with poorly sorted coarse sand. Any slope over this threshold created a stream, while any slope under the threshold created a meandering stream or— for very low slopes—a straight channel. Also important to development is the proportion of suspended load sediment to bed load. The channels and braid bars are highly mobile, with the river layout often changing significantly during flood events. Channels move sideways via differential velocity, On the outside of a curve, deeper, swift water picks up sediment, the braided channels may flow within an area defined by relatively stable banks or may occupy an entire valley floor. The Rakaia River in Canterbury, New Zealand has cut a channel 100 metres wide into the surrounding plains, extensive braided river systems are found in Alaska, Canada, New Zealands South Island, and the Himalayas, which all contain young, rapidly eroding mountains. The enormous Brahmaputra-Jamuna River in Asia is an example of a braided river. Braided river systems are present in Africa, for example in the Touat Valley, a notable example of a large braided stream in the contiguous United States is the Platte River in central and western Nebraska. The sediment of the arid Great Plains is augmented by the presence of the nearby Sandhills region north of the river, a portion of the lower Yellow River takes a braided form. Others have interpreted the depositional environment for this unit as a tidal delta, ait Anabranch Lagoon Shoal Hibbert, Barry, Brown, Kerry, eds
Braided river
–
The
Waimakariri River is braided over most of its course.
Braided river
–
The
White River in the
U.S. state of
Washington transports a large sediment load from the
Emmons Glacier of
Mount Rainier, a young, rapidly eroding volcano.
Braided river
–
Rakaia River, South Island, New Zealand
Braided river
–
Tanana River, Fairbanks, Alaska, United States
46.
Cut bank
–
A cut bank, also known as a river cliff or river-cut cliff, is the outside bank of a water channel, which is continually undergoing erosion. Cut banks are found in abundance along mature or meandering streams, they are located on the outside of a bend, known as a meander. They are shaped much like a cliff, and are formed by the erosion of soil as the stream collides with the river bank. As opposed to a point bar which is an area of deposition, typically, cut banks are nearly vertical and often expose the roots of nearby plant life. Often, particularly during periods of rainfall and higher-than average water levels, trees. Given enough time, the combination of erosion along cut banks, not only are cut banks steep and unstable, they are also the area of a stream where the water is flowing the fastest at a higher pressure and often deeper, making them rather dangerous. Geologically speaking, this is known as an area of high-energy, material eroded here is deposited downstream in point bars. Bank erosion Point bar Slip-off slope Tarbuck, E. J. and F. K. Lutgens, prentice Hall, Upper Saddle River, New Jersey,2002
Cut bank
–
Cut
bank erosion and
point bar deposition as seen on the
Powder River in
Montana.
Cut bank
–
Cut banks along the
Cut Bank Creek
