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, 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 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
Heinrich Barth was a German explorer of Africa and scholar. He was among the first to comprehend the uses of history of peoples. He established friendships with African rulers and scholars during his five years of travel, after the deaths of two European companions, he completed his travels with the aid of Africans. Afterwards, he wrote and published an account of his travels in both English and German. It has been invaluable for scholars of his time and since, Heinrich Barth was born in Hamburg on 16 February 1821. He was the child of Johann Christoph Heinrich Barth and his wife Charlotte Karoline née Zadow. Johann had come from a poor background but had built up a successful trading business. Both parents were orthodox Lutherans and they expected their children to conform to their ideas on morality. From the age of eleven Barth attended the high school. He was very studious but not popular with his classmates and he excelled at languages and taught himself some Arabic. After his first year he interrupted his studies and went on a tour of Italy visiting Venice, Rome and Sicily, in the vacation of the following year he visited the Rhineland and Switzerland.
He defended his thesis on the trade relations of ancient Corinth in July 1844. Barth formed a plan to undertake a tour of north Africa. While in London he met the Prussian ambassador to Britain, Christian von Bunsen and he left London and travelled across France and Spain. On 7 August he caught a ferry from Gibraltar to Tangiers for his first visit to Africa, from Tangier, he made his way overland across North Africa. He travelled through Egypt, ascending the Nile to Wadi Halfa, while in Egypt, he was attacked and wounded by robbers. Crossing the Sinai peninsula, he traversed Palestine, Asia Minor and Greece and he returned to his parents home in Hamburg on 27 December 1847 after a trip of almost three years. For a time he was engaged there as Privatdozent and he described some of his travels in the first volume of his book, Wanderungen durch die Küstenländer des Mittelmeeres, which was published in 1849
Elephants are large mammals of the family Elephantidae and the order Proboscidea. Three species are recognised, the African bush elephant, the African forest elephant, Elephants are scattered throughout sub-Saharan Africa, South Asia, and Southeast Asia. Elephantidae is the surviving family of the order Proboscidea, now extinct, members of the order include deinotheres, mammoths. Male African elephants are the largest extant terrestrial animals and can reach a height of 4 m, all elephants have several distinctive features, the most notable of which is a long trunk or proboscis, used for many purposes, particularly breathing, lifting water, and grasping objects. Their incisors grow into tusks, which can serve as weapons and as tools for moving objects, Elephants large ear flaps help to control their body temperature. Their pillar-like legs can carry their great weight, African elephants have larger ears and concave backs while Asian elephants have smaller ears and convex or level backs. Elephants are herbivorous and can be found in different habitats including savannahs, forests and they prefer to stay near water.
They are considered to be keystone species due to their impact on their environments, other animals tend to keep their distance from elephants while predators, such as lions, tigers and wild dogs, usually target only young elephants. Females tend to live in groups, which can consist of one female with her calves or several related females with offspring. The groups are led by a known as the matriarch. Elephants have a society in which multiple family groups come together to socialise. Males leave their family groups when they reach puberty and may live alone or with other males, calves are the centre of attention in their family groups and rely on their mothers for as long as three years. Elephants can live up to 70 years in the wild and they communicate by touch, sight and sound, elephants use infrasound, and seismic communication over long distances. Elephant intelligence has been compared with that of primates and cetaceans and they appear to have self-awareness and show empathy for dying or dead individuals of their kind.
African elephants are listed as vulnerable by the International Union for Conservation of Nature while the Asian elephant is classed as endangered, one of the biggest threats to elephant populations is the ivory trade, as the animals are poached for their ivory tusks. Other threats to elephants include habitat destruction and conflicts with local people. Elephants are used as working animals in Asia, in the past, they were used in war, they are often controversially put on display in zoos, or exploited for entertainment in circuses. Elephants are highly recognisable and have featured in art, religion, literature
Twin reversed arterial perfusion
Twin Reversed Arterial Perfusion sequence—also called TRAP sequence, TRAPS, or acardiac twinning—is a rare complication of monochorionic twin pregnancies. It is a variant of twin-to-twin transfusion syndrome. The twins blood systems are connected instead of independent, one twin, called the acardiac twin or TRAP fetus, is severely malformed. The heart is missing or deformed, hence the name acardiac, the legs may be partially present or missing, and internal structures of the torso are often poorly formed. The other twin is usually normal in appearance, the normal twin, called the pump twin, drives blood through both fetuses. It is called reversed arterial perfusion because in the twin the blood flows in a reversed direction. TRAP sequence occurs in 1% of monochorionic twin pregnancies and in 1 in 35,000 pregnancies overall, the acardiac twin is a parasitic twin that fails to properly develop a heart, and therefore generally does not develop the upper structures of the body. Although the reason is not fully understood, it is apparent that deoxygenated blood from the twin is perfused to the acardiac twin.
The acardiac twin grows along with the twin, but due to inadequate oxygenation it is unable to develop the structures necessary for life. Although no two acardiac twins are alike, twins with this disorder are grouped into 4 classes, anceps, Acephalus - The most common type, lacking a head, though it may have arms. Thoracic organs are absent, and disorganized & unidentifiable tissues take their place. Anceps - The acardius has most body parts, including a head with face, though present, are crudely formed. Acormus - This type has no apparent body and the cord is seemingly attached to the neck. One had a leg apparently attached to the head and this may be due to embryopathy degenerating a once normal embryo. Amorphus - This extreme form not only lacks a head and limbs, but any internal organs, some may only be stem cell tumors. The acardiac twin may be described as a hemiacardius, which has an incompletely formed heart, or a holoacardius, the rate of fatality depends on the relative size of the acardiac twin.
If the abnormal twin is greater than 50% of the size of the pump twin, TRAP sequence can be diagnosed using obstetric ultrasound. Doppler interrogation will confirm that blood flow in the twin is in the reverse direction, entering via the umbilical cord artery
Cave of Swimmers
The Cave of Swimmers is a cave with ancient rock art in the mountainous Gilf Kebir plateau of the Libyan Desert section of the Sahara. It is located in the New Valley Governorate of southwest Egypt, the cave and rock art was discovered in October 1933 by the Hungarian explorer László Almásy. It contains Neolithic pictographs and is named due to the depictions of people with their limbs bent as if they were swimming. They are estimated to have created as early as 10,000 years ago with the beginning of the African Humid Period. Almásy devoted a chapter to the cave in his 1934 book and this theory was so new at that time that his first editor added several footnotes, to make it clear that he did not share this opinion. In 2007, Eman Ghoneim discovered an ancient mega-lake buried beneath the sand of the Great Sahara in the Northern Darfur region, the cave is mentioned in Michael Ondaatjes novel The English Patient and the film adaptation based upon it. The cave shown in the film is not the original but a set created by a contemporary artist.
Physical scientists who have been doing research in the area drew a link between the proposed swimming humans and two lakes that are 124 miles south of the cave. However, Andras Zboray, an archaeologist who is doing research in the area and he believes that the drawings are clearly symbolic. with an unknown meaning. Jean-Loïc Le Quellec, a doctor of anthropology and prehistory and he has pointed out parallels to the Coffin Texts indicating that the figures are deceased souls floating in the waters of Nun. Substantial portions of the cave have been damaged by visitors over the years. Fragments of the paintings have been removed as souvenirs and some surfaces have cracked after water was applied to enhance their contrast for photographs, modern graffiti have been inscribed upon the wall and tourist littering is a problem. Saharan rock art László Almásy, The Unknown Sahara, translation of the Hungarian original Az Ismeretlen Szahara,2002, by Andras Zboray Ladislaus E. Almasy, Schwimmer in der Wüste.
Auf der Suche nach der Oase Zarzura, DTV, München, ISBN 3-423-12613-2 The Cave of Swimmers Egyptian caves. Accessed March 2008 Cosmos magazine People followed the rains in ancient Sahara Friday,21 July 2006 by Marie Theresa Bray, accessed March 2008 https, //skfb. ly/UBOS 3D model
University of the Aegean
The University of the Aegean is a state, multi-campus university located in Lesvos, Samos, Rhodes and Lemnos, Greece. The university was founded in 1984, although its historical roots date back to the early 1920s. The University of the Aegean is a university, one of the 24 state supervised and funded universities in Greece. It is an institution mandated to provide innovative and socially committed studies, furthermore, in 2011, the Teaching and Research Staff numbered 292 people, the Scientific Teaching Staff numbered 99 and the Special Laboratory Teaching Staff 23 people. This is further supported by the 30 members of the Special Technical Laboratory Staff for teaching services, the first Department to operate, in the academic year 1984-85, was the department of Business Administration, in the island of Chios. In the following year, the Department of Primary School Education, in Rhodes, the university today comprises 5 schools and 16 departments offering undergraduate and post-graduate degrees programmes.
The newest academic unit was created on the island of Lemnos in 2009, the University of the Aegean, as all Universities in Greece, is a public university. As such, its activities and a small part of its research activities rely upon government funding. These activities are supported by funds generated by the Research Unit. Research in the University is funded through participation in national and international research. Since 2014 the University is facing economic hardship due to austerity policies resulting in minimal state funding. The large majority of the campuses is situated in the historical birthplaces of ancient and contemporary Greek philosophers and mathematicians such as Pythagoras. The foundations of the University of the Aegean date back to October 1918 when Greece had expanded its borders to the wider Smyrna area after the World War I. Consequently, the Greek Government decided to materialize Carathéodorys vision and establish the Ionian University, Constantin Carathéodory was the first dean of the university.
However, the Ionian University stopped its operations due to the Great Fire of Smyrna in 1922 and its focus spans across a number of diverse disciplines - Environmental Studies, Sociology and Educational Design. Students study the subject of the Department in which they get admitted at. Bachelor of Science courses range from 4 to 5 years and Master of Science courses range from 1 to 2 years. The Ministry of Education is aiming to reform Higher Education programmes by 2014, the universitys Senate issued a formal response to the Ministry of Educations proposed plan in 2013
Western Desert (Egypt)
The Western Desert of Egypt is an area of the Sahara which lies west of the river Nile, up to the Libyan border, and south from the Mediterranean sea to the border with Sudan. It is named in contrast to the Eastern Desert which extends east from the Nile to Red Sea, the Western Desert is mostly rocky desert, though an area of sandy desert, known as the Great Sand Sea, lies to the west against the Libyan border. The desert covers an area of 262,800 sq miles which is two-thirds of the area of the country. Its highest elevation is 3,300 ft in the Gilf Kebir plateau to the far south-west of the country, the Western Desert is barren and uninhabited save for a chain of oases which extend in an arc from Siwa, in the north-west, to Kharga in the south. However it has been the scene of conflict in modern times and he states that little of the area conforms to the romantic view. These lie in an arc from Siwa in the north-west near the Libyan border, to Bahariya, Dakhla, east of Siwa lies the Qattara Depression, a low-lying area dotted with salt marsh and extending 190 miles west to east and 84 miles north to south.
Further to the east, near the Nile, another depression gives rise to the Fayyum Oasis, to the south, beyond the Bahariya oasis lies the Black Desert, an area of black volcanic hills and dolerite deposits. Beyond this, north of Farafra, lies the White Desert, an area of wind-sculpted chalk rock formations, which give the area its name. To the south of Kharga the plateau rises towards the Gilf Kebir, an upland region lying astride the Egypt-Sudan border and home to pre-historic sites such as the Cave of Swimmers. In the south-west, near the point where the borders of Libya and Egypt meet, is an area of glass, thought to have been formed by a meteorite strike at Kebira. The Great Sand Sea is a roughly lung-shaped area of sandy desert lying astride the border with Libya,200 miles inland from the Mediterranean. The sea is divided by a peninsula of rocky desert along the border, leaving the eastern lobe in Egypt and the western in Libya. On the Egyptian side it extends from a point south of Siwa for 400 miles into the interior, the Western Desert was known historically as the Libyan Desert, taking its name from Ancient Libya, which lay between the Nile and Cyrenaica.
With the formation of the state of Libya, the term Western Desert has come to describe part of the Sahara in Egypt. To the Ancient Greeks, the term Libya described the whole Saharan littoral west of the Nile to the Atlas mountains. During Roman times the term Libya was limited to Cyrenaica and the region between there and Egypt, which were organized as the provinces of Libya Superior and Libya Inferior, the term Libyan Desert applied to the area to the south of these. Playfair described the Western Desert of 1940 as being 240 miles wide and 150 miles wide, the contemporary use of the term refers to the entire desert in Egypt west of the Nile. It is thought over-grazing and climate led to desertification and the current geography
It ended when metal tools became widespread. The Neolithic is a progression of behavioral and cultural characteristics and changes, including the use of wild and domestic crops, the beginning of the Neolithic culture is considered to be in the Levant about 10, 200–8800 BC. It developed directly from the Epipaleolithic Natufian culture in the region, whose people pioneered the use of wild cereals, which evolved into true farming. The Natufian period was between 12,000 and 10,200 BC, and the so-called proto-Neolithic is now included in the Pre-Pottery Neolithic between 10,200 and 8800 BC. By 10, 200–8800 BC, farming communities arose in the Levant and spread to Asia Minor, North Africa, Mesopotamia is the site of the earliest developments of the Neolithic Revolution from around 10,000 BC. Early Neolithic farming was limited to a range of plants, both wild and domesticated, which included einkorn wheat and spelt, and the keeping of dogs, sheep. By about 6900–6400 BC, it included domesticated cattle and pigs, the establishment of permanently or seasonally inhabited settlements, not all of these cultural elements characteristic of the Neolithic appeared everywhere in the same order, the earliest farming societies in the Near East did not use pottery.
Early Japanese societies and other East Asian cultures used pottery before developing agriculture, unlike the Paleolithic, when more than one human species existed, only one human species reached the Neolithic. The term Neolithic derives from the Greek νέος néos, new and λίθος líthos, the term was invented by Sir John Lubbock in 1865 as a refinement of the three-age system. In the Middle East, cultures identified as Neolithic began appearing in the 10th millennium BC, early development occurred in the Levant and from there spread eastwards and westwards. Neolithic cultures are attested in southeastern Anatolia and northern Mesopotamia by around 8000 BC. The total excavated area is more than 1,200 square yards, the Neolithic 1 period began roughly 10,000 years ago in the Levant. A temple area in southeastern Turkey at Göbekli Tepe dated around 9500 BC may be regarded as the beginning of the period. This site was developed by nomadic tribes, evidenced by the lack of permanent housing in the vicinity.
At least seven stone circles, covering 25 acres, contain limestone pillars carved with animals, Stone tools were used by perhaps as many as hundreds of people to create the pillars, which might have supported roofs. Other early PPNA sites dating to around 9500–9000 BC have been found in Jericho, Gilgal in the Jordan Valley, the start of Neolithic 1 overlaps the Tahunian and Heavy Neolithic periods to some degree. The major advance of Neolithic 1 was true farming, in the proto-Neolithic Natufian cultures, wild cereals were harvested, and perhaps early seed selection and re-seeding occurred. The grain was ground into flour, emmer wheat was domesticated, and animals were herded and domesticated
James David Lewis-Williams is a South African archaeologist. He is best known for his research on southern African San rock art and he is the founder and previous director of the Rock Art Research Institute and is currently professor emeritus of cognitive archaeology at the University of the Witwatersrand. Lewis-Williams is recognised by the National Research Foundation of South Africa as a leading international researcher, Lewis-Williams was exposed to social anthropology as an undergraduate at UCT. During this time he received lectures from renowned social anthropologist A. R. Radcliffe-Brown and Monica Wilson, from the start of his career and in contrast to most scholars of the period, Lewis-Williams was looking at San rock art from a social anthropological perspective. Overall he recorded some 4000 images for his thesis research. His PhD, finished in 1977 and published in 1981 as Believing and Seeing, is regarded as a seminal text in rock art research globally. The quantitative method now bears little impact on the understanding of meaning behind images in San rock art, there is simply too much ambiguity in what the numerical values can be said to imply.
In the early 1980s Lewis-Williams began to other theoretical approaches. This was because he At that time in South Africa, during apartheid, Marxism was the language of liberation, in The economic and social context of southern San rock art, Lewis-Williams explored the economic position of the shaman in San society. Using Maurice Godeliers ideas of work, Lewis-Williams investigated the ritual role of shamans in terms of San social structure. Concerns for the members of San society are seen in his research that draws on A foundation to Lewis-Williamss work has been the use of ethnography. As an undergraduate he was exposed to Isaac Schaperas The Khoisan Peoples of South Africa From the start of his career he drew on ethnography to address the meaning of San rock art. Although he never met her, Bleek’s daughter, Dorothea Bleek, which derives from the Siberian Tungus word shaman, was used by Lewis-Williams to explain the metaphor of death common to both ethnography and San rock art. The shamanic world often has tiered realms inhabited by spirits that can be accessed through altered states of consciousness, the world inhabited by people is supplemented by other realms that are usually conceptualised as existing above or below the inhabited world.
Shamans have the ability to mediate between these other worlds, as San shamans dance, their supernatural power, or ‘potency’, builds up until it reaches a breaking point and flies out of the body. At this point, they ‘die’, a metaphor for travelling to another realm where spirits dwell in the way as the soul travels after leaving after physical death. The trance dance has been demonstrated to correlate with symbolism in the rock art, features depicted in images relate that relate to altered states of consciousness, such as nasal bleeding and the ‘arms back’ posture, are two illustrative examples known to occur during the dance. Indeed, Lewis-Williams writes that The idea of a belief system was expanded upon using neuropsychology
In archaeology, rock art is human-made markings placed on natural stone, it is largely synonymous with parietal art. A global phenomenon, rock art is found in many diverse regions of the world. It has been produced in many contexts throughout history, although the majority of rock art that has been ethnographically recorded has been produced as a part of ritual. Such artworks are often divided into three forms, which are carved into the surface, which are painted onto the surface. The oldest known rock art dates from the Upper Palaeolithic period, having found in Europe, Asia. Archaeologists studying these artworks believe that they likely had magico-religious significance, Rock art continues to be of importance to indigenous peoples in various parts of the world, who view them as both sacred items and significant components of their cultural patrimony. Such archaeological sites are significant sources of cultural tourism, and have been utilised in popular culture for their aesthetic qualities.
Normally found in cultures, a rock relief or rock-cut relief is a relief sculpture carved on solid or living rock such as a cliff. They are a category of art, and sometimes found in conjunction with rock-cut architecture. However, they tend to be omitted in most works on rock art, a few such works exploit the natural contours of the rock and use them to define an image, but they do not amount to man-made reliefs. Rock reliefs have been made in many cultures, and were important in the art of the Ancient Near East. Rock reliefs are generally large, as they need to be to make an impact in the open air. Most have figures that are over life-size, and in many the figures are multiples of life-size, the vertical relief is most common, but reliefs on essentially horizontal surfaces are found. The term typically excludes relief carvings inside caves, whether natural or themselves man-made, natural rock formations made into statues or other sculpture in the round, most famously at the Great Sphinx of Giza, are usually excluded.
Reliefs on large boulders left in their location, like the Hittite İmamkullu relief, are likely to be included. The term rock art appears in the literature as early as the 1940s. It has described as rock carvings, rock drawings, rock engravings, rock inscriptions, rock paintings, rock pictures. The defining characteristic of rock art is that it is placed on natural rock surfaces, as such, rock art is a form of landscape art, and includes designs that have been placed on boulder and cliff faces, cave walls and ceilings, and on the ground surface
Inside the Neolithic Mind
It was first published by Thames and Hudson in 2005. Following on from Lewis-Williams earlier work, The Mind in the Cave, academic reviews published in such peer-reviewed journals as Antiquity were mixed. Critics argued that the use of evidence was selective, and that there was insufficient evidence for the authors three-stage model of entopic phenomenon, others praised the accessible and engaging writing style. In their preface, Lewis-Williams and Pearce explain their approach, and their reasons for comparing megalithic art and archaeology from the Near East, chapter one, The Revolutionary Neolithic, explores the background to this period of time, in which humans became increasingly sedentary and developed agriculture. Moving on to an exploration of why humans adopted agriculture, they proclaim their adherence to Jacques Cauvins concept of the Symbolic Revolution, from there, they discuss the role of religion, suggesting that it should be understood as a tripartite system uniting experience and belief.
Lewis-Williams and Pearce round off the chapter by quoting Samuel Taylor Coleridges poem Kubla Khan, in the second chapter, The Consciousness Contract, the authors explore such altered states of consciousness, beginning with a discussion of the life and work of Jean-Jacques Rousseau. Listing the symptoms of such altered states, they put forward their three-stage model for how the human brain experiences these states, and interprets them as recognisable images. They follow this with a discussion of the symbolism of the eye, drawing comparisons with the eyes in the clay statues from Ain Ghazal. In doing so, the authors draw parallels with the ethnographically-recorded Barasana people of Amazonia, chapter six, Treasure the Dream Whatever the Terror, discusses how aspects of consciousness and cosmology can make their way into myth, expanding on the problematic nature of defining myth. The seventh chapter, The Mound in the Dark Grove, turns its attention to Atlantic Europe, on the western end of the continent.
Opening with a reference to William Blake, the authors focus their attention on two Early Neolithic tombs on the island of Anglesey off the Welsh coast, Bryn Celli Ddu and Barclodiad y Gawres. Chapter eight, Brú na Bóinne, examines the valley of the name in County Meath, Ireland. Exploring ritual elements to the act of flint mining at sites as Grimes Graves. He noted that archaeologists would be receptive to their idea that geometric patterns on European megaliths have parallels with similarities in Southern Africa. Concluding his review, Balter remarked that the authors can be assured that their foray into the Neolithic mind will not be ignored
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, Egypt, Mali, Morocco, 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, the Ténéré, the Libyan Desert, the Eastern Desert.
These extremely arid areas often receive no rain for years, the northern limit 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