HUMANPAST.NET

Environment                  40,000 BC
Africa
Southwest Asia
Egypt
Indus Valley
China
Europe
South America
Mesoamerica
North America
Other

In General

I have reviewed the evidence for three displacements of the earth's crust during the last 110,000 years. They seem to have occurred at intervals of 30,000 to 40,000 years. There are indications that they may have occurred at this rate through much of the Pleistocene Epoch. From the evidence we now have it seems futile to try to determine the locations of the poles in the more remote cases. With every step backward in time the evidence naturally becomes thinner. (132)

In conclusion, it appears to me that the whole mass of the evidence relative to the animal and plant remains in the Siberian tundra, interpreted in the light of the evidence from North America, sufficiently confirms the conclusion that there was a northward displacement of Siberia coincident with the southward displacement of North America at the end of the last North American ice age. (132)

What is now clear is that during the last ice age, and the period that followed it, the climate was much more chaotic than it has been in recent millennia. Generally, the climate was much more variable. Sudden changes occurred from time to time. Collapse of parts of the ice sheets, or release of meltwater lakes that built up behind the ice, led to cataclysmic changes. Armadas of icebergs or floods of icy freshwater swept out into the North Atlantic altering the circulation of the ocean at a stroke and with it the climate of the neighbouring continents. With a flick of the climatic switch, Europe and much of North America could be plunged back into icy conditions, having only just emerged from the abyss of the preceding millennia. Conversely, the stability of the glacial conditions could be interrupted by a re-establishment of the flow of warm water to higher latitudes in the North Atlantic, bringing surprising temporary warmth to the northern continents. (145)

...the isotopic temperature records show some 20 interstadials, ...between 15 and 100 kya. Typically the events start with an abrupt warming of Greenland of some 5 to 10°C over a few decades or less. This warming is followed by a gradual cooling over several hundred years, and occasionally much longer. This cooling phase often ends with an abrupt final reduction of temperature back to cold ('stadial') conditions. (145)

Changes in the sea level during the last 100 kyr. (145)

 

Africa

 

Southwest Asia

 In Israel a detailed lake-level history of the closed Lake Lisan (part of the ancient Dead Sea) indicates that for much of the period from 55 kya to the end of the ice age the level was higher than at present. There were, however, catastrophic droughts associated with the Heinrich events. The impression is that cold-water input to the Mediterranean originating in the collapse of North Atlantic Deep Water formation caused a reduction of evaporation and less precipitation in the Levant. So it is reasonable to conclude that following Heinrich events 6, 5, and 3 much of the Middle East was desert. During these intervals, of which the long cold period from around 67 to 59 kya was the most significant, the region was largely uninhabitable for modern humans. (145)

Egypt

 A wet climate began in North Africa 50,000 years ago and lasted for 20,000 years. Called the Mousterian Pluvial, this wet era allowed the Sahara to bloom with plants and wildlife, but also with new human settlements. (70)

Indus Valley

 

China

 

Europe

  By 75,000 years ago glacial conditions had begun in Europe, and a great ice sheet formed, perhaps on a land bridge connecting the British Isles with Iceland and Greenland. After a few thousand years it had grown thick enough to move out from the center of thickest accumulation by gravity. It covered Ireland, filled the Irish Sea basin and swept across the Welsh mountains into England about 55,000 years ago. Its advance, it appears, required a period of 20,000 to 25,000 years, comparable to the time that was apparently required for the growth of the Wisconsin ice sheet. ...a polar shift occurred at about the time this ice sheet reached its maximum: the shift from the Greenland Sea to Hudson Bay. It is easy to connect the two events: The shift brought the advance to an end and initiated the glacial retreat. This retreat probably started long before 42,000 years ago, and by about 37,000 years ago the ice sheet had left the Irish Sea basin. The decline of the Irish Sea ice sheet seems to have required a period of time similar to the time required for the decline of the Wisconsin ice sheet. The parallel is extremely interesting. (132)

A study of the reports on the frozen mammoths reveals some very remarkable facts. In the first place, they increase in numbers the farther north one goes, and are most numerous in the New Siberian Islands, which lie between the Arctic coast of Siberia and the pole. Secondly, they are accompanied by many other kinds of animals. Thirdly, although ivory is easily ruined by exposure to the weather, uncounted thousands of pairs of tusks have been preserved in good enough conditions for the ivory trade. A fourth point is that the bodies of many mammoths and a few other animals have been preserved so perfectly (in the frozen ground) as to be edible today. Finally, astonishing as it may seem, it is not true that the mammoth was adapted to a very cold climate. ...we are at least justified...in rejecting the claims advanced for the hair of the mammoth as an adaptive feature to a very cold climate. (132)

...we know that along with the millions of mammoths, the northern Siberian plains supported vast numbers of rhinoceroses, antelope, horses, bison, and other herbivorous creatures, while a variety of carnivores, including the sabertooth cat, preyed upon them. What good does it do to argue that the mammoth was adapted to cold when it is impossible to use the argument in the case of several of the other animals? No doubt it was knowledge of these conditions that caused the great founder of modern geology, Sir Charles Lyell, to remark that it would doubtless be impossible for herds of mammoths and rhinoceroses to subsist throughout the year, even in the southern part of Siberia. If this is the case with Siberia, what are we to think when we contemplate the New Siberian Islands? There the remains of mammoths and other animals are most numerous of all. There Baron Toll, the Arctic explorer, found remains of a sabertooth tiger, and a fruit tree that had been ninety feet tall when it was standing. The tree was well preserved in the permafrost, with its roots and seeds. Toll claimed that green leaves and ripe fruit still clung to its branches. Yet, at the present time, the only representative of tree vegetation on the islands is a willow that grows one inch high. Naturally the knowledge that the Arctic islands, though they are now in polar darkness much of the year, were in very recent geologic times able to grow the flourishing forests of a temperate climate eliminates any need to insist that they were always as cold as they are today. Thus it is not a question at all of whether the climate grew colder but merely a question of when the change occurred. (132)

According to Lydekker, about 20,000 pairs of tusks, in perfect condition, were exported for the ivory trade in the few decades preceding 1899, yet even now there is no end in sight. ...In many instances, as is well known, entire carcasses of the mammoth have been found thus buried, with the hair, skin and flesh as fresh as in frozen New Zealand sheep in the hold of a steamer. And sleigh dogs, as well as Yakuts themselves, have often made a hearty meal on mammoth flesh thousands of years old. In instances like these it is evident that mammoths must have been buried and frozen almost immediately after death; but as the majority of the tusks appear to be met with in an isolated condition, often heaped one atop another, it would seem that the carcasses were often broken up by being carried down the rivers before their final entombment. Even then, however, the burial, or at least the freezing, must. have taken place comparatively quickly as exposure in their ordinary condition would speedily deteriorate the quality of the ivory. (132)

It seems that the preservation of meat by freezing requires some rather special conditions. Herbert Harris, in an article on Birdseye in Science Digest, writes: What Birdseye had proved was that the faster a food can be frozen at "deep" temperatures of around minus 40 degrees Fahrenheit, the less chance there is of forming the large ice crystals that tear down cellular walls and tissues leaving gaps through which escape the natural juices, nutriment and flavor. ...take poultry giblets; they can last eight months at 10 below zero, but "turn" in four weeks above it. Or lobster. It lasts 24 months at 10 below but less than twenty days at anything above...Herz said that "the flesh is fibrous and marbled with fat." It "looks as fresh as well frozen beef." While it is on the one hand clear that the ground in which the bodies are found has been hard frozen since the carcasses were entombed, it is no less inevitable that when these same carcasses were originally entombed, the ground must have been soft and unfrozen. You cannot thrust flesh into hard frozen earth without destroying it. It follows, from this analysis of the mechanics of freezing, that the preservation of mammoth meat for thousands of years may be accounted for by normal initial freezing, followed by a sharp fall in temperature. Whenever the meat was preserved in an edible condition the deep freeze must have been uninterrupted; there must have been no thaws sufficient to bring the temperature near the freezing point. (132)

The discovery of the ripe fruits of sedges, grasses, and other plants suggests that "the mammoth died during the second half of July or the beginning of August." The age of the mammoth, however, turns out to be at least 39,000 years, and possibly as much as 47,500 years. Where does this leave us? Can we fit this into our scheme? It appears from this timing (which there is no reason to doubt) that the Beresovka Mammoth died when the climate in Siberia was warming up - after the pole had left the Greenland Sea and migrated to America. (132)

The warmth was such that it enabled humans to occupy parts of Siberia as far north as the Arctic Circle on the banks of the Usa River, close to the Ural Mountains, nearly 40 kya, and this occupation appears to have extended to the Yana River valley within 2000 km of the Bering Straits by 30 kya. As with much of Siberia, there was a maximum in forest development across Beringia between around 33 and 39 kya. In general, in the east of the region vegetation showed less propensity to swing between stadial and interstadial conditions, whereas near­interglacial forests alternated with more glacial-like tundra in western Beringia. The 'flickering' of the interstadial forests suggests great climatic variability in the west, in contrast to the more stable climatic regime farther east. (145)

South America

 We have two areas lying at similar distances from their respective poles. In one, the northern, we have many evidences of heavy glaciation, extending over a period of perhaps 40,000 years, but ending about 14,000 years ago, to give way to the present climate about 10,000 years ago. In Chile and Argentina, on the other hand, in the same relative latitude just as close, presumably, to a pole, we have no glaciation until after the climate has become normal for the present temperate zone in the north. It appears that in Argentina a cool period set in just as the hipsithermal phase with higher temperatures set in all over the northern hemisphere! Clearly, then, there was no similarity in climatic trends, but rather the opposite. (132)

Burmeister says, "the diluvial deposit containing bones of animals of this age extends over the whole Brazilian plain, from the flanks of the Cordilleras to the borders of the Atlantic." They have also been found abundantly in Bolivia on the great plateau; and also west of the mountains both in Peru and Chile. From Caracas in the north, to the sierra of Tandel in Patagonia in the south, they have, in fact, occurred in more or less abundance over the whole continent. In the great Argentine plain they are found close to the sea-level, while in Bolivia they occur, according to D'Orbigny, at a height of 4000 metres, and they are found with a singular similarity if not uniformity of contents in all latitudes. Nor is there any doubt that both sets of beds date from the same horizon as the Mammoth beds of other countries. The fauna of the Pleistocene beds of the Southern States of North America is, in fact, largely identical with that from the beds we are now discussing; the megatherium and mylodon, the tapir and capybara, the mastodon and horse being found in both, and every observer, from Darwin to Burmeister, is agreed in assigning them to the same horizon. (132)

Mesoamerica

 

North America

 Today, Eskimos using skin boats easily cross the ninety kilometers of open sea separating Siberia and America, and recently an American woman slathered herself with grease and actually swam from Alaska to Siberia. But such a sea crossing would not have been necessary during much of the Pleistocene. During periods of glacial advance within the last million years, enourmous quantities of water were converted to ice, lowering the sea level sufficiently to expose a 1500- to 3000-kilometer-wide expanse of the floor of the Bering Sea. This land bridge--usually referred to as Beringia--was probably available at least four times in the last 60,000 years.(25)

Prior to 10,000 years ago, species of deer, bison,camels, bears, foxes, mammoths, moose, caribou,and even rodents crossed from Siberia into the New World. Going in the other way--from America to Asia--were foxes, woodchucks, and, during the early Pliestocene, the ancestors of modern forms of horses, wolves, and other animals.(25)

...the initial phase, the beginning of the Wisconsin glaciation, was rather sudden. A vast unglaciated area was covered all at once with snow which did not melt. Several lines of solid evidence suggest that during the last ice age the North Pole was located in or near Hudson Bay. ...the best guess for the site of the pole seems to be approximately 60 degrees North Latitude and 83 degrees West Longitude. The first line of evidence that the last North American ice cap was a polar ice cap is based on the shape, size, and peculiar geographical location of the ice sheet. (132)

A very remarkable evidence of the suddenness with which the ice cap was born is the fact that it contained thousands (and perhaps millions) of animals of a temperate climate, many of them frozen entire into the ice, including mastodons, mammoths, bear, elk, beaver, and so forth. When the ice cap melted, many of these animals were dropped into bogs, which preserved their bodies and sometimes even the contents of their stomachs. It is evident enough, from the assemblage of species, that the snow overwhelmed them while they were living in temperate conditions. What this may mean is actually rather frightening to contemplate. (132)

Thus we are able to say that warm conditions in the Arctic Archipelago of Canada persisted for the entire duration of the Wisconsin glaciation, from 40,000 years ago down to the establishment of modern conditions. Yes, if the pole were in Hudson Bay, the Arctic should be warm. And the Arctic was warm. However, there is much more evidence. ...the Arctic Ocean was warm during most of the ice age, particularly from about 32,000 to about 18,000 years ago.
Temperate conditions had evidently prevailed in Antarctica in the not distant past. The sediment indicated that no fewer than three times during the Pleistocene Epoch a temperate climate had prevailed in the Ross Sea. (132)

We have two areas lying at similar distances from their respective poles. In one, the northern, we have many evidences of heavy glaciation, extending over a period of perhaps 40,000 years, but ending about 14,000 years ago, to give way to the present climate about 10,000 years ago. In Chile and Argentina, on the other hand, in the same relative latitude just as close, presumably, to a pole, we have no glaciation until after the climate has become normal for the present temperate zone in the north. It appears that in Argentina a cool period set in just as the hipsithermal phase with higher temperatures set in all over the northern hemisphere! Clearly, then, there was no similarity in climatic trends, but rather the opposite. (132)

In many places the Alaskan muck is packed with animal bones and debris in trainload lots. Bones of mammoth, mastodon, several kinds of bison, horses, wolves, bears, and lions tell a story of a faunal population... The Alaskan muck is like a fine, dark gray sand...Within this mass, frozen solid, lie the twisted parts of animals and trees intermingled with lenses of ice and layers of peat and mosses. It looks as though in the midst of some cataclysmic catastrophe of ten thousand years ago the whole Alaskan world of living animals and plants was suddenly frozen in midmotion in a grim charade... Throughout the Yukon and its tributaries, the gnawing currents of the river had eaten into many a frozen bank of muck to reveal bones and tusks of these animals protruding at all levels. Whole gravel bars in the muddy river were formed of the jumbled fragments of animal remains... ...the animals of the period wandered into every corner of the New World not actually covered by the ice sheets. Their bones lie bleaching on the sands of Florida and in the gravels of New Jersey. They weather out of the dry terraces of Texas and protrude from the sticky ooze of the tar pits of Wilshire Boulevard in Los Angeles. Thousands of these remains have been encountered in Mexico and even in South America. The bodies lie as articulated skeletons revealed by dust storms, or as isolated bones and fragments in ditches or canals. The bodies of the victims are everywhere in evidence. (132)

...where we can study these animals in some detail, such as in the great bone pits of Nebraska, we find literally thousands of these remains together. The young lie with the old, foal with dam and calf with cow. Whole herds of animals were apparently killed together, overcome by some common power. Interspersed in the muck depths and sometimes through the very piles of bones and tusks themselves are layers of volcanic ash. There is no doubt that coincidental with the end of the Pleistocene animals, at least in Alaska, there were volcanic eruptions of tremendous proportions. It stands to reason that animals whose flesh is still preserved must have been killed and buried quickly to be preserved at all. Bodies that die and lie on the surface soon disintegrate and the bones are scattered. A volcanic eruption would explain the end of the Alaskan animals all at one time, and in a manner that would satisfy the evidences there as we know them. The herds would be killed in their tracks either by the blanket of volcanic ash covering them and causing death by heat or suffocation, or, indirectly, by volcanic gases. Toxic clouds of gas from volcanic upheavals could well cause death on a gigantic scale... (132)

Studies of stalagmites from a cave in southeastern Missouri show remarkably little variation after a marked cooling around 55 kya. Prior to this, conditions appear to have oscillated more frequently. The warmest temperatures occurred around 57 kya and there were short-lived cooling events around 64, 71 and 74 kya. Beetle assemblages suggest that, following the cooling around 55 kya, the mean July temperature was 7.5-8°C lower than present and mean January value was 15-18°C lower than present. During what is termed the 'mid-Wisconsin' interstadial, dating from 43.5 to 39 kya, there was a rapid and intense warming. At the peak of this event, about 42kya, July temperatures were only 1-2°C lower than modern. (145)

Other

 Around the time of the onset of OIS3 the Australian climate entered a wetter phase. These moister conditions prevailed until around 40 kya, with only occasional drier periods lasting up to a millennium, although there is evidence of an increasing incidence of dry periods towards the end of this period. Then the climate became much more arid. The transition to increasing aridity appears to have coincided with the arrival of humans in Australia, which is now estimated to have been around 60kya. (145)