In Old World archaeology, Mesolithic is the period between the Upper Paleolithic and the Neolithic. The term Epipaleolithic is used synonymously for outside northern Europe, for the corresponding period in the Levant and Caucasus; the Mesolithic has different time spans in different parts of Eurasia. It refers to the final period of hunter-gatherer cultures in Europe and Western Asia, between the end of the Last Glacial Maximum and the Neolithic Revolution. In Europe it spans 15,000 to 5,000 BP; the term is less used of areas further east, not at all beyond Eurasia and North Africa. The type of culture associated with the Mesolithic varies between areas, but it is associated with a decline in the group hunting of large animals in favour of a broader hunter-gatherer way of life, the development of more sophisticated and smaller lithic tools and weapons than the heavy chipped equivalents typical of the Paleolithic. Depending on the region, some use of pottery and textiles may be found in sites allocated to the Mesolithic, but indications of agriculture are taken as marking transition into the Neolithic.
The more permanent settlements tend to be close to the sea or inland waters offering a good supply of food. Mesolithic societies are not seen as complex, burials are simple; the terms "Paleolithic" and "Neolithic" were introduced by John Lubbock in his work Pre-historic Times in 1865. The additional "Mesolithic" category was added as an intermediate category by Hodder Westropp in 1866. Westropp's suggestion was controversial. A British school led by John Evans denied any need for an intermediate: the ages blended together like the colors of a rainbow, he said. A European school led by Louis Laurent Gabriel de Mortillet asserted that there was a gap between the earlier and later. Edouard Piette claimed to have filled the gap with his naming of the Azilian Culture. Knut Stjerna offered an alternative in the "Epipaleolithic", suggesting a final phase of the Paleolithic rather than an intermediate age in its own right inserted between the Paleolithic and Neolithic. By the time of Vere Gordon Childe's work, The Dawn of Europe, which affirms the Mesolithic, sufficient data had been collected to determine that a transitional period between the Paleolithic and the Neolithic was indeed a useful concept.
However, the terms "Mesolithic" and "Epipalaeolitic" remain in competition, with varying conventions of usage. In the archaeology of Northern Europe, for example for archaeological sites in Great Britain, Scandinavia and Russia, the term "Mesolithic" is always used. In the archaeology of other areas, the term "Epipaleolithic" may be preferred by most authors, or there may be divergences between authors over which term to use or what meaning to assign to each. In the New World, neither term is used. "Epipaleolithic" is sometimes used alongside "Mesolithic" for the final end of the Upper Paleolithic followed by the Mesolithic. As "Mesolithic" suggests an intermediate period, followed by the Neolithic, some authors prefer the term "Epipaleolithic" for hunter-gatherer cultures who are not succeeded by agricultural traditions, reserving "Mesolithic" for cultures who are succeeded by the Neolithic Revolution, such as the Natufian culture. Other authors use "Mesolithic" as a generic term for post-LGM hunter-gatherer cultures, whether they are transitional towards agriculture or not.
In addition, terminology appears to differ between archaeological sub-disciplines, with "Mesolithic" being used in European archaeology, while "Epipalaeolithic" is more common in Near Eastern archaeology. The Balkan Mesolithic begins around 15,000 years ago. In Western Europe, the Early Mesolithic, or Azilian, begins about 14,000 years ago, in the Franco-Cantabrian region of northern Spain and southern France. In other parts of Europe, the Mesolithic begins by 11,500 years ago, it ends with the introduction of farming, depending on the region between c. 8,500 and 5,500 years ago. Regions that experienced greater environmental effects as the last glacial period ended have a much more apparent Mesolithic era, lasting millennia. In northern Europe, for example, societies were able to live well on rich food supplies from the marshlands created by the warmer climate; such conditions produced distinctive human behaviors that are preserved in the material record, such as the Maglemosian and Azilian cultures.
Such conditions delayed the coming of the Neolithic until some 5,500 BP in northern Europe. The type of stone toolkit remains one of the most diagnostic features: the Mesolithic used a microlithic technology – composite devices manufactured with Mode V chipped stone tools, while the Paleolithic had utilized Modes I–IV. In some areas, such as Ireland, parts of Portugal, the Isle of Man and the Tyrrhenian Islands, a macrolithic technology was used in the Mesolithic. In the Neolithic, the microlithic technology was replaced by a macrolithic technology, with an increased use of polished stone tools such as stone axes. There is some evidence for the beginning of construction at sites with a ritual or astronomical significance, including Stonehenge, with a short row of large post holes aligned east-west, a possible "lunar calendar" at Warren Field in Scotland, with pits of post holes of varying sizes, thought to reflect the lunar phases. Both are dated to before c. 9,000 BP. As the "Neolithic package" (including farming, polished stone axes, timber longhouses and pot
Beirut–Rafic Hariri International Airport
Beirut–Rafic Hariri International Airport Beirut International Airport, is located 9 kilometres from the city center in the southern suburbs of Beirut, is the only operational commercial airport in the country. It is the hub for Middle East Airlines, it is the hub for the Lebanese charter carrier Wings of Lebanon, was the hub for the Lebanese cargo carrier TMA cargo before its collapse. It is the main port of entry into the country along with the Port of Beirut; the airport is managed and operated by the Directorate General of Civil Aviation, which operates within the Ministry of Public Works and Transport. The DGCA is responsible for operating the air traffic control at the airport as well as controlling Lebanon's airspace. DGCA duties include maintenance and general upkeep ranging from cleaning the terminal to de-rubberising the runways; the airport opened on 23 April 1954, replacing the much smaller Bir Hassan Airfield, located a short distance north. At the time of its opening, the terminal was modern and it featured an excellent spotters terrace with a café.
The airport consisted of two asphalt runways at the time. Runway 18/36 at 3,250 metres was used for landings from the 18 end while runway 03/21 at 3,180 metres was used for take-offs from the 21 end and from the Sami end; the airport grew to become a premier hub in the Middle East, thanks to limited competition from neighbours, with fast and steady growth by the country's four carriers at the time, Middle East Airlines, Air Liban, Trans Mediterranean Airways, Lebanese International Airways, numerous other foreign carriers. In response to an attack on El Al Flight 253 two days earlier in Athens, on the night of 28 December 1968, Israeli commandos mounted a surprise attack on the airport and destroyed 14 civilian aircraft operated by the Lebanese carriers, Middle East Airlines, Trans Mediterranean Airways, Lebanese International Airways; this caused serious devastation to the Lebanese aviation industry. Middle East Airlines managed to rebound but Lebanese International Airways went bankrupt and its employees were transferred to MEA.
The airport lost its status as one of the premier hubs of the Middle East with the start of the 15-year-long Lebanese Civil War in April 1975 and lost all of its airline services with the exception of two Lebanese carriers, Middle East Airlines and Trans Mediterranean Airways. Both airlines continued operating with the exception of certain periods of time when the airport itself was closed. Despite the conflict, the terminal was renovated in 1977, only to be badly damaged five years by Israeli shelling during the 1982 Israeli invasion of Lebanon; the airport was the site of the 1983 Beirut barracks bombing, in which 241 American servicemen were killed. The airport's runways were renovated in 1982 and 1984. By the time war came to an end in 1990, the airport needed to launch a massive reconstruction program. A ten-year reconstruction program was launched in 1994 which included the construction of another terminal, two runways, a fire station, a power plant, a general aviation terminal, an underground parking garage.
Many structures, like the radar building, were rehabilitated. In 1998 the first phase of the new terminal was completed, it was located adjacent to the east of the old terminal and consists of gates 1–12. After it was inaugurated, the old terminal was demolished and construction on the western half began and was completed in 2000, however it was not inaugurated until 2002; this consists of gates 13–23. The new terminal can handle 6 million passengers annually and is expected to be expanded to handle 16 million passengers by 2035, it was decided early on. A new landing runway, 17/35 was constructed protruding at an angle out into the sea, with a length of 3,395 metres; this seaward protrusion was built in order to move landing traffic away from the city in a bid to improve safety and reduce aircraft noise. A new take-off runway was constructed parallel to the old 03/21 at a length of 3,800 metres making it the longest runway in the airport; the old 03/21 was converted to a taxiway for accessing the new runway 03/21.
Unlike the old runways, the two new runways were constructed from concrete and feature more advanced lighting systems and instrument landing systems. In 2004, runway 17/35 was re-designated 16/34 and runway 18/36 was re-designated 17/35 after more accurate runway heading measurements were conducted. Despite being replaced by and adjacent to the new runway 16/34, runway 17/35 is still open, although it is used. On 17 June 2005, the General Aviation Terminal was opened, it is located on the northwestern corner of the airport. All fixed-base operators and VIP charter providers have moved their operations to this state-of-the-art terminal. In 2005, the airport was renamed from "Beirut International Airport" to "Beirut–Rafic Hariri International Airport" in honor of former Lebanese Prime Minister Rafic Hariri, assasssinated earlier in the year. On 13 July 2006 at 6:00 a.m. local time, all three runways of the airport sustained significant damage from missile strikes directed at it by the Israeli Air Force as part of the 2006 Lebanon War.
The Israeli Air Force claimed that the airport was a military target because Hezbollah was receiving weapons shipments there. The runways were rendered inoperative and the Leba
An arrowhead is a tip sharpened, added to an arrow to make it more deadly or to fulfill some special purpose. The earliest arrowheads were made of organic materials. Arrowheads are important archaeological artifacts. Modern enthusiasts still "produce over one million brand-new spear and arrow points per year". One who manufactures metal arrowheads is an arrowsmith. In the Stone Age, people used sharpened bone, flintknapped stones and chips of rock as weapons and tools; such items remained in use with new materials used as time passed. As archaeological artifacts such objects are classed as projectile points, without specifying whether they were projected by a bow or by some other means such as throwing since the specific means of projection is found too in direct association with any given point and the word "arrow" would imply a certainty about these points which does not exist; such artifacts can be found all over the world in various locations. Those that have survived are made of stone consisting of flint, obsidian or chert.
In many excavations, bone and metal arrowheads have been found. Stone projectile points dating back 64,000 years were excavated from layers of ancient sediment in Sibudu Cave, South Africa. Examinations found traces of blood and bone residues, glue made from a plant-based resin, used to fasten them on to a wooden shaft; this indicated. These hafted points might have been launched from bows. While "most attributes such as micro-residue distribution patterns and micro-wear will develop on points used to tip spears, darts or arrows" and "explicit tests for distinctions between thrown spears and projected arrows have not yet been conducted" the researchers find "contextual support" for the use of these points on arrows: a broad range of animals were hunted, with an emphasis on taxa that prefer closed forested niches, including fast moving and arboreal animals; this is an argument for the use of traps including snares. If snares were used, the use of cords and knots which would have been adequate for the production of bows is implied.
The employment of snares demonstrates a practical understanding of the latent energy stored in bent branches, the main principle of bow construction. Cords and knots are implied by use-wear facets on perforated shell beads around 72,000 years old from Blombos. Archeologists in Louisiana have discovered that early Native Americans used Alligator gar scales as arrow heads. "Hunting with a bow and arrow requires intricate multi-staged planning, material collection and tool preparation and implies a range of innovative social and communication skills." Arrowheads are attached to arrow shafts to be shot from a bow. The arrowhead or projectile point is the primary functional part of the arrow, plays the largest role in determining its purpose; some arrows may use a sharpened tip of the solid shaft, but it is far more common for separate arrowheads to be made from metal, rock, or some other hard material. Arrowheads may be attached to the shaft with a cap, a socket tang, or inserted into a split in the shaft and held by a process called hafting.
Points attached with caps are slid snugly over the end of the shaft, or may be held on with hot glue. In medieval Europe, arrowheads were adhered with hide glue. Split-shaft construction involves splitting the arrow shaft lengthwise, inserting the arrowhead, securing it using ferrule, rope, or wire. Modern arrowheads used for hunting come in a variety of styles. Many traditionalist archers choose heads made of modern high carbon steel that resemble traditional stone heads. Other classes of broadheads referred to; these heads rely on force created by passing through an animal to expand or open. Arrowheads are separated by function: Bodkin points are short, rigid points with a small cross-section, they were made of unhardened iron and may have been used for better or longer flight, or for cheaper production. It has been suggested that the bodkin came into its own as a means of penetrating armour, however limited research has so far found no hardened bodkin points, so it appears that it was first designed either to extend range or as a cheaper and simpler alternative to the broadhead.
In a modern test, a direct hit from a hard steel bodkin point penetrated a set of fifteenth-century chain armour made in Damascus. However, archery was minimally effective against plate armour, which became available to knights of modest means by the late 14th century. Blunts are unsharpened arrowheads used for types of target shooting, for shooting at stumps or other targets of opportunity, or hunting small game when the goal is to stun the target without penetration. Blunts are made of metal or hard rubber, they may stun, the arrow shaft may penetrate the head and the target. Judo points have spring wires extending sideways from the tip; these catch on debris to prevent the arrow from being lost in the vegetation. Used for practice and for small game. Broadheads are still used for hunting. Medieval broadheads could be made from steel, sometimes with hardened edges, they have two to four sharp blades that cause massive bleeding in the victim. Their function is to
The Neolithic, the final division of the Stone Age, began about 12,000 years ago when the first development of farming appeared in the Epipalaeolithic Near East, in other parts of the world. The division lasted until the transitional period of the Chalcolithic from about 6,500 years ago, marked by the development of metallurgy, leading up to the Bronze Age and Iron Age. In Northern Europe, the Neolithic lasted until about 1700 BC, while in China it extended until 1200 BC. Other parts of the world remained broadly in the Neolithic stage of development, although this term may not be used, until European contact; the Neolithic comprises a progression of behavioral and cultural characteristics and changes, including the use of wild and domestic crops and of domesticated animals. The term Neolithic derives from the Greek νέος néos, "new" and λίθος líthos, "stone" meaning "New Stone Age"; the term was coined by Sir John Lubbock in 1865 as a refinement of the three-age system. Following the ASPRO chronology, the Neolithic started in around 10,200 BC in the Levant, arising from the Natufian culture, when pioneering use of wild cereals evolved into early farming.
The Natufian period or "proto-Neolithic" lasted from 12,500 to 9,500 BC, is taken to overlap with the Pre-Pottery Neolithic of 10,200–8800 BC. As the Natufians had become dependent on wild cereals in their diet, a sedentary way of life had begun among them, the climatic changes associated with the Younger Dryas are thought to have forced people to develop farming. By 10,200–8800 BC farming communities had arisen in the Levant and spread to Asia Minor, North Africa and North Mesopotamia. Mesopotamia is the site of the earliest developments of the Neolithic Revolution from around 10,000 BC. Early Neolithic farming was limited to a narrow range of plants, both wild and domesticated, which included einkorn wheat and spelt, the keeping of dogs and goats. By about 6900–6400 BC, it included domesticated cattle and pigs, the establishment of permanently or seasonally inhabited settlements, the use of pottery. 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.
In other parts of the world, such as Africa, South Asia and Southeast Asia, independent domestication events led to their own regionally distinctive Neolithic cultures, which arose independently of those in Europe and Southwest Asia. Early Japanese societies and other East Asian cultures used pottery before developing agriculture. In the Middle East, cultures identified as Neolithic began appearing in the 10th millennium BC. Early development occurred from there spread eastwards and westwards. Neolithic cultures are attested in southeastern Anatolia and northern Mesopotamia by around 8000 BC; the prehistoric Beifudi site near Yixian in Hebei Province, contains relics of a culture contemporaneous with the Cishan and Xinglongwa cultures of about 6000–5000 BC, neolithic cultures east of the Taihang Mountains, filling in an archaeological gap between the two Northern Chinese cultures. The total excavated area is more than 1,200 square yards, the collection of neolithic findings at the site encompasses two phases.
The Neolithic 1 period began around 10,000 BC in the Levant. A temple area in southeastern Turkey at Göbekli Tepe, dated to around 9500 BC, may be regarded as the beginning of the period; this site was developed by nomadic hunter-gatherer tribes, as evidenced by the lack of permanent housing in the vicinity, may be the oldest known human-made place of worship. At least seven stone circles, covering 25 acres, contain limestone pillars carved with animals and birds. Stone tools were used by 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, West Bank, Gilgal in the Jordan Valley, Byblos, Lebanon; the start of Neolithic 1 overlaps the 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, early seed selection and re-seeding occurred; the grain was ground into flour. Emmer wheat was domesticated, animals were herded and domesticated.
In 2006, remains of figs were discovered in a house in Jericho dated to 9400 BC. The figs are of a mutant variety that cannot be pollinated by insects, therefore the trees can only reproduce from cuttings; this evidence suggests that figs were the first cultivated crop and mark the invention of the technology of farming. This occurred centuries before the first cultivation of grains. Settlements became more permanent, with circular houses, much like those of the Natufians, with single rooms. However, these houses were for the first time made of mudbrick; the settlement had a surrounding stone wall and a stone tower. The wall served as protection from nearby groups, as protection from floods, or to keep animals penned; some of the enclosures suggest grain and meat storage. The Neolithic 2 began around 8800 BC according to the ASPRO chronology in the Levant; as with the PPNA dates, there are two versions from the same laboratories noted above. This system of terminology, however, is not convenient for southeast Anatolia and settlements of the middle Anatolia basin.
A settlement of 3,000 inhabitants was found in th
The Upper Paleolithic is the third and last subdivision of the Paleolithic or Old Stone Age. Broadly, it dates to between 50,000 and 10,000 years ago, according to some theories coinciding with the appearance of behavioral modernity and before the advent of agriculture. Anatomically modern humans are believed to have emerged out of Africa around 200,000 years ago, although these lifestyles changed little from that of archaic humans of the Middle Paleolithic, until about 50,000 years ago, when there was a marked increase in the diversity of artefacts; this period coincides with the expansion of modern humans from Africa throughout Asia and Eurasia, which contributed to the extinction of the Neanderthals. The Upper Paleolithic has the earliest known evidence of organized settlements, in the form of campsites, some with storage pits. Artistic work blossomed, with cave painting, petroglyphs and engravings on bone or ivory; the first evidence of human fishing is found, from artefacts in places such as Blombos cave in South Africa.
More complex social groupings emerged, supported by more varied and reliable food sources and specialized tool types. This contributed to increasing group identification or ethnicity; the peopling of Australia most took place before c. 60 ka. Europe was peopled after c. 45 ka. Anatomically modern humans are known to have expanded northward into Siberia as far as the 58th parallel by about 45 ka; the Upper Paleolithic is divided during about 25 to 15 ka. The peopling of the Americas occurred during this time, with East and Central Asia populations reaching the Bering land bridge after about 35 ka, expanding into the Americas by about 15 ka. In Western Eurasia, the Paleolithic eases into the so-called Epipaleolithic or Mesolithic from the end of the LGM, beginning 15 ka; the Holocene glacial retreat begins 11.7 ka, falling well into the Old World Epipaleolithic, marking the beginning of the earliest forms of farming in the Fertile Crescent. Both Homo erectus and Neanderthals used the same crude stone tools.
Archaeologist Richard G. Klein, who has worked extensively on ancient stone tools, describes the stone tool kit of archaic hominids as impossible to categorize, it was as if the Neanderthals made stone tools, were not much concerned about their final forms. He argues that everywhere, whether Asia, Africa or Europe, before 50,000 years ago all the stone tools are much alike and unsophisticated. Firstly among the artefacts of Africa, archeologists found they could differentiate and classify those of less than 50,000 years into many different categories, such as projectile points, engraving tools, knife blades, drilling and piercing tools; these new stone-tool types have been described as being distinctly differentiated from each other. The invaders referred to as the Cro-Magnons, left many sophisticated stone tools and engraved pieces on bone and antler, cave paintings and Venus figurines; the Neanderthals continued to use Mousterian stone tool technology and Chatelperronian technology. These tools disappeared from the archeological record at around the same time the Neanderthals themselves disappeared from the fossil record, about 40,000 cal BP.
Settlements were located in narrow valley bottoms associated with hunting of passing herds of animals. Some of them may have been occupied year round, though more they appear to have been used seasonally. Hunting was important, caribou/wild reindeer "may well be the species of single greatest importance in the entire anthropological literature on hunting."Technological advances included significant developments in flint tool manufacturing, with industries based on fine blades rather than simpler and shorter flakes. Burins and racloirs were used to work bone and hides. Advanced darts and harpoons appear in this period, along with the fish hook, the oil lamp and the eyed needle; the changes in human behavior have been attributed to changes in climate, encompassing a number of global temperature drops. These led to a worsening of the bitter cold of the last glacial period; such changes may have reduced the supply of usable timber and forced people to look at other materials. In addition, flint may not have functioned as a tool.
Some scholars argue that the appearance of complex or abstract language made these behavior changes possible. The complexity of the new human capabilities hints that humans were less capable of planning or foresight before 40,000 years, while the emergence of cooperative and coherent communication marked a new era of cultural development; the climate of the period in Europe saw dramatic changes, included the Last Glacial Maximum, the coldest phase of the last glacial period, which lasted from about 26.5 to 19 kya, being coldest at the end, before a rapid warming. During the Maximum, most of Northern Europe was covered by an ice-sheet, forcing human populations into the areas known as Last Glacial Maximum refugia, including modern Italy and the Balkans, parts of the Iberian Peninsula and areas around the Black Sea; this period saw cultures such as the Solutrean in Spain. Human life may have continued on top of the ice sheet, but we know next to nothing about it, little about the human life that preceded the European glaciers.
In the early part of the period, up to a
The Pleistocene is the geological epoch which lasted from about 2,588,000 to 11,700 years ago, spanning the world's most recent period of repeated glaciations. The end of the Pleistocene corresponds with the end of the last glacial period and with the end of the Paleolithic age used in archaeology; the Pleistocene is the first epoch of the Quaternary Period or sixth epoch of the Cenozoic Era. In the ICS timescale, the Pleistocene is divided into four stages or ages, the Gelasian, Middle Pleistocene and Upper Pleistocene. In addition to this international subdivision, various regional subdivisions are used. Before a change confirmed in 2009 by the International Union of Geological Sciences, the time boundary between the Pleistocene and the preceding Pliocene was regarded as being at 1.806 million years Before Present, as opposed to the accepted 2.588 million years BP: publications from the preceding years may use either definition of the period. Charles Lyell introduced the term "Pleistocene" in 1839 to describe strata in Sicily that had at least 70% of their molluscan fauna still living today.
This distinguished it from the older Pliocene epoch, which Lyell had thought to be the youngest fossil rock layer. He constructed the name "Pleistocene" from the Greek πλεῖστος, pleīstos, "most", καινός, kainós, "new"; the Pleistocene has been dated from 2.588 million to 11,700 years BP with the end date expressed in radiocarbon years as 10,000 carbon-14 years BP. It covers most of the latest period of repeated glaciation, up to and including the Younger Dryas cold spell; the end of the Younger Dryas has been dated to about 9640 BC. The end of the Younger Dryas is the official start of the current Holocene Epoch. Although it is considered an epoch, the Holocene is not different from previous interglacial intervals within the Pleistocene, it was not until after the development of radiocarbon dating, that Pleistocene archaeological excavations shifted to stratified caves and rock-shelters as opposed to open-air river-terrace sites. In 2009 the International Union of Geological Sciences confirmed a change in time period for the Pleistocene, changing the start date from 1.806 to 2.588 million years BP, accepted the base of the Gelasian as the base of the Pleistocene, namely the base of the Monte San Nicola GSSP.
The IUGS has yet to approve a type section, Global Boundary Stratotype Section and Point, for the upper Pleistocene/Holocene boundary. The proposed section is the North Greenland Ice Core Project ice core 75° 06' N 42° 18' W; the lower boundary of the Pleistocene Series is formally defined magnetostratigraphically as the base of the Matuyama chronozone, isotopic stage 103. Above this point there are notable extinctions of the calcareous nanofossils: Discoaster pentaradiatus and Discoaster surculus; the Pleistocene covers the recent period of repeated glaciations. The name Plio-Pleistocene has, in the past, been used to mean the last ice age; the revised definition of the Quaternary, by pushing back the start date of the Pleistocene to 2.58 Ma, results in the inclusion of all the recent repeated glaciations within the Pleistocene. The modern continents were at their present positions during the Pleistocene, the plates upon which they sit having moved no more than 100 km relative to each other since the beginning of the period.
According to Mark Lynas, the Pleistocene's overall climate could be characterized as a continuous El Niño with trade winds in the south Pacific weakening or heading east, warm air rising near Peru, warm water spreading from the west Pacific and the Indian Ocean to the east Pacific, other El Niño markers. Pleistocene climate was marked by repeated glacial cycles in which continental glaciers pushed to the 40th parallel in some places, it is estimated. In addition, a zone of permafrost stretched southward from the edge of the glacial sheet, a few hundred kilometres in North America, several hundred in Eurasia; the mean annual temperature at the edge of the ice was −6 °C. Each glacial advance tied up huge volumes of water in continental ice sheets 1,500 to 3,000 metres thick, resulting in temporary sea-level drops of 100 metres or more over the entire surface of the Earth. During interglacial times, such as at present, drowned coastlines were common, mitigated by isostatic or other emergent motion of some regions.
The effects of glaciation were global. Antarctica was ice-bound throughout the Pleistocene as well as the preceding Pliocene; the Andes were covered in the south by the Patagonian ice cap. There were glaciers in New Tasmania; the current decaying glaciers of Mount Kenya, Mount Kilimanjaro, the Ruwenzori Range in east and central Africa were larger. Glaciers existed to the west in the Atlas mountains. In the northern hemisphere, many glaciers fused into one; the Cordilleran ice sheet covered the North American northwest. The Fenno-Scandian ice sheet rested including much of Great Britain. Scattered domes stretched across Siberi