Chapter 2: Berelekh River

 

Map of Northeast Siberia, where they have found the remains of the woolly mammoth and its companions. The Berelekh River lies west of the lower Indigirka River and flows into the Delta of the Indigirka, near the present Arctic Coast. From: Vereshchagin and Barshnikov (1982) Fig. 1

 

Northeastern Siberia is a huge mammoth-graveyard. Many bones and tusks of this elephant have been preserved in the frozen ground. Also many bones of the woolly rhinoceros, the bison and the wild horse they have found up there. How many tusks have been found there? Of how many mammoths? Why are there so many tusks and bones? How have they come into the frozen ground? In what kind of a climate has this elephant lived in northern Siberia?

N. K. Vereshchagin is Professor at the Zoological Institute of the Russian Academy of Sciences in St. Petersburg. He is one of Russia’s leading mammoth experts. He reports in his article "The Mammoth ‘Cemeteries’ of North-East Siberia":

"The north of Yakutia has long been known to be an immense store-house of frozen disjointed bones of many hundreds of thousands of large Pleistocene mammals – mammoths, horses, woolly rhinoceroses, bison, musk-oxen – ‘horned cattle’, as the first Russian travellers called them. ... In quality these tusks, which have lain in frozen ground for tens of millennia, are as good as those of modern African and Indian elephants and are sometimes two or three times larger. For naturalists, the greatest interest lies in the discovery of whole frozen bodies or of skulls and complete skeletons." (1974:3).

"During the last glaciation, Würm I-II-III in western Europe, this plain stretched some 500-600 km farther north, a fact proved by the presence of permafrost on the continental shelf. The plain had a dry continental climate colder than at present, for the veins of ground ice formed then are several times larger than the biggest veins of the Holocene period. Although there was little precipitation, the cool climate hindered evaporation and this frozen plain produced during its short hot summer a lush crop of grasses, a fact demonstrated by finds of frozen grasses and by the bones of a very large number of herbivores. ... Much of the present Yana-Kolyma lowland, which stands 25-30 m above sea level, is formed of alluvial deposits and preserved raised beaches with layers of drift wood, evidence of marine transgression during the Pleistocene.

"The region is rich in lakes, which, taken together with river meanders, occupy 30-40 per cent of the surface. The lakes are formed by the thawing of ground ice and are relatively short-lived because fractures beneath them lead to drainage. On the drained lakes (alas in Yakut), grows a luxuriant cover of grass, which changes in two or three decades to a boggy sedge-and-moss cover characteristic of the tundra. There are also, in some places, rounded hills (yedoma in Yakut), about 10-15 m high, which are gradually being washed away by the lakes. The yedoma, also called mammoth graves, are fragments of the former surface of the Pleistocene plain, which also supported a large number of herbivores. At first glance it is difficult to believe that the erosional activity of lakes has lowered the Pleistocene plain by 10-15 m during the past few millennia.

"Some 60-90 per cent of these relict areas are composed of polygonal (many-edged) veins of ancient ground ice that reach depths of 30-40 m and that surround pillars of frozen loess 2-3 m in diameter. The vertical sections of such columns of ground ice and soil are particularly spectacular on the south shore of Proliv Dmitriya Lapteva and on Ostrov Bol’shoy Lyakhovskiy, and the sea cliffs are very rich in mammoth bones. ... Certainly, during glacial and especial interglacial periods, great rivers crossed the plain, but the interfluves were raised through the accumulation of ground ice and possibly of aeolian dust. ... During the late Pleistocene, the Arctic Ocean was evidently small and ice-covered, a condition unfavourable to the creation of cyclones.

"Solifluction also contributes to the erosion of relict high ground. The sun warms the slopes, causing landslides that leave columns of earth from around which the ice veins have thawed. These mounds (baydzherakh in Yakut) look like giant molehills on a chessboard. In these areas, in gullies and stream beds, are the disjointed skeletons and tusks of mammoths, horses, woolly rhinoceroses, reindeer, musk-oxen, bison, and cave lion. Sometimes these bones have been gnawed by predators, which suggests that they have been lying on the surface for sometime. Many bones and even tusks are broken, evidently by ice pressure. The great abundance of bones of large herbivores in the yedoma is convincing evidence of the rich pasturage offered by this region during the Pleistocene, a fact confirmed by pollen analysis of sediment samples, which indicates an assemblage of tundra-steppe plants, including many cereal grasses. The loess probably served as fertilizer and ensured a large primary biomass." - Vereshchagin, N. K. (1974:4-6).

How preserved

Professor N. K. Vereshchagin then asks: "How, then, were these bones preserved?". – And replies: "In general, skulls and other bones disappear rather quickly through the action of rodents, fungus, sun and rain, but in this region, during the Pleistocene, conditions often effected a more or less speedy burial. One important factor was the fall of loess on the cold wet ground. However, this deposition could hardly have exceeded 2-3 cm a year and, at that rate, it would have taken 20-30 years to cover a mammoth, during which time the bones and tusks would have been almost entirely destroyed by atmospheric processes. But on an open windy plain, loess behaves like dry snow, drifting in hollows, forming cornices on slopes, filling gullies, etc.

"We first studied a large ‘cemetery’ on the river Berelekh, a west tributary of the Indigirka in lat. 71°N. There about 3 500 bones of Pleistocene animals had been collected from the river bank, and as many more were recovered from the permafrost by hosing away the soil. The total number of skeletal remains exceeded 8500 bones, predominantly mammoth bones. Other bones (wolf, wolverine, cave lion, Arctic hare, horse, woolly rhinoceros, reindeer and bison) totalled 134, only 1.5 per cent.

"At Berelekh, the river cut through a 16-m yedoma. The upper third of this hill is composed of light grey aeolian loess of Würm III age, and the lower two-thirds of loess-like river loams of the Würm II-III interstadial period. When the ice veins in the upper third thawed, bones of mammoths, bisons, and horses fell out, and most of them were buried in a former stream bed, now 7-8 m above the level of the present river and on the south-east side of the yedoma.

"We found about 140 individual mammoths in the Berelekh cemetery. They probably died on the upper proto-Berelekh and were carried down-stream at high water after break-up to this point, where they lodged, decayed, and were covered by deposits of the ancient river. It is very doubtful that their deaths occurred simultaneously. Probably small groups died each year during the winter from blizzards or in spring or autumn when crossing ice.

"Judging by the predominance of thin tusks,70-80 mm in diameter at the alveolus, and by the small teeth and skulls, the Berelekh stream bed contained mainly females and half-grown males. Embryo humeral and tibial bones, 13-15 cm long, were found, which indicates a local, not a visiting population, although long seasonal migrations along the valleys are not excluded.

"Some tusks and hollow bones were broken, and some were coated in vivianite, which suggests that the bones had at some time lain in a dried-out water body. Bones and skulls, in chaotic disarray, were sometimes intertwined with brownish strands of hair and wool with pieces of skin. ... The back leg of one large mammoth retained a mummified muscle structure under its thick skin and short brown-gold wool on the tarsus and hoof." - Vereshchagin, N. K. (1974:6, 7).

Great Lyakhov Island

Great Lyakhov Island is one of the New Siberian Islands. Also there, north of the present Arctic Coast, the frozen bones and whole bodies of animals of the late Pleistocene mammoth fauna have been recovered. – Professor N. K. Vereshchagin explains:

"In August 1972, I intended to study the Novosibirskiye Ostrova, but heavy ice prevented my reaching the islands. I concentrated therefore on the south shore of Proliv Dmitriya Lapteva, east of Mys Svyatoy Nos. We found here the classical 40-m steep-walled bank containing veins and baydzherakh. Along the bank, about 20 m down, protruded giant tusks weighing 70-80 kg and 350 cm long. In gullies intersecting this layer we found many bones of horses and reindeer and skulls of large musk-oxen and small bison. In places there were 35-m vertical cliffs of structureless strata of silty loams, sometimes with a layer of larch debris at 30 m. ...

"In any case, for good preservation of soft tissues and internal organs, there must have been sufficiently quick covering-over of the body by deposits, which then froze. The season in which the animal died was of great importance. If at the beginning of summer, the body would decay in warm weather or be eaten by predators and larvae. But frozen after death in autumn or winter, the body would have thawed in summer in the same way as mossy tundra, to a depth of only 28-30 cm. If the body lay in a gully or beneath a north-facing slope, it might not thaw at all, especially if it were in a snow patch. In such a position it stood a good chance of being buried beneath a solifluction landslide and of being preserved for millennia." (1974:8, 9).

How many tusks found

How many mammoth tusks have they found in north-east Siberia? And how many tusks are there still buried in the frozen ground?

Professor N. K. Vereshchagin explains: "Zenzinov (1915) has calculated that in the 250 years since the beginning of the mammoth-ivory industry in north-east Siberia in 1660, the tusks of about 46 750 mammoths have been recovered. ... To form an impression of the abundance of bones of large animals in the upper part of the loess of Würm III age, we made a detailed study of gentle solifluction slopes of loam with ground ice on various yedoma in the region of Allaikha, Berelekh, and Oyegosskiy Yar. We found 10-30 bones per hectare, on average about 20. Most of the pieces were hollow bones and mammoth and bison vertebrae. Only about one tusk per three hectares was found, and these tusks were often half decayed. At the mouths of gullies and other locations of active erosion, the number of bones and tusks can be significantly higher, for there they are concentrated from several horizons.

"Through lake and sea erosion of the Pleistocene plain, most tusks have been displaced by lake beds and onto the continental shelf and are at least temporarily inaccessible under water or in horizons not at present subject to erosion. The number of tusks that has been or will be recovered by man is an insignificant fraction of those buried in alluvial deposits. If the south shore of Proliv Dmitriya Lapteva is eroded by sea and thermokarst at a width of 2 m along 150 km annually, then more than 6000 bones will disappear each season into the strait, among them 90-100 tusks.

"In August 1972, along 10 km of bank at Oyegosskiy Yar, we found seven tusks, weighing together 350 kg. Next season, these tusks will have disappeared into the silty shoals for more millennia. Because we know that in the north-east such shallows extend about 550-650 km off-shore, we may calculate that in the 1000 km between the Yana and the Kolyma are deposited some 550 000 tons of mammoth tusks (taking 30 kg as an average). Within the confines of the present marine plain, lake deposits should contain roughly 150 000 tons of tusks." - Vereshchagin, N. K. (1974:10, 11). 

Why they died out

If the woolly mammoth has been so well adapted to an extreme arctic climate, why, then, is it not grazing up there now anymore? Why has also the woolly rhinoceros and bison died out up there?

Professor N. K. Vereshchagin: "The death of an individual or a herd of mammoths does not explain the extinction of their whole population in north-east Siberia. Their extinction in Siberia, together with the woolly rhinoceros, bison, and cave lion, must have occurred about 10 000-12 000 years ago, because there are no later dated records. This date coincides with the end of the last glacial epoch, when important changes in climate, vegetation and landscape took place over much of the world and led to the gradual extinction of or to a major change in range of many large animals. ... The low sedge-and-moss communities of tundra started to replace the grasses, and these plants could not support the mammoths and other large herbivores. The more luxuriant growth in valleys was drifted deeply in snow during winter and often flooded during the short summer.

"From a study of the mammoth ‘cemeteries’ of north-east Siberia, it seems clear that the destruction of this rich complex of Late Pleistocene animals took place about 10 000 years ago as a result of the transformation of a cold dry grassy steppe into a boggy lake-filled tundra that produced little fodder and was covered by snow in winter. Neither mammoth nor bison could exist in the sort of tundra that exists there today." - Vereshchagin, N. K. (1974:11, 12). 

Mammoth Steppe and present Tundra

In what kind of a climate has the woolly mammoth lived in north-east Siberia and on the continental shelf, reaching then some 500 to 600 km further north? Could this hairy elephant have lived up there on a tundra, as it is growing there now? This is important, because even now, some Pleistocene paleontologists still do believe that the woolly mammoth was able to live in the Far North, just like the reindeer and the musk-ox of today.

Professor N. K. Vereshchagin and F. Baryshnikov report about their newer findings in the book Paleoecology of Beringia (1982:267-269): "An analysis of the morphology and ecology of the late Pleistocene mammoth fauna of arctic Eurasia indicates that they lived in a cold, dry climate in steppe and steppe-tundra biotopes and characterized by hard, frozen ground. ... Very large individuals of mammoth would have required 200 to 300 kg of succulent feed daily, and they must have caused considerable damage to floodplain vegetation. ... Among the remains of some 140 mammoths excavated from the Berelekh ‘mammoth cemetery’, 30% are juveniles 10 years old or less, and 2% are foetuses. ...

"Landscapes and biotopes. – Morphoecological data indicate that mammoths inhabited open landscapes of meadows and steppes with shrub thickets in the river valleys. Winters were probably extremely severe and cold with little snow and no watering places. That soils were generally firm and dry is indicated by the prevalence of fast-moving cursorial species such as horse, bison, and saiga antelope, by the relatively small hooves of many ungulates, and by the wide distribution of deep burrowers among the smaller animals. At present the soil thaws only to depths of 28 to 30 cm beneath the moss cover of lowland tundra at 70°N latitude in Yakutia. It could hardly have thawed more deeply under a grass cover during the Pleistocene time, but the ground must have remained firm and dry and swampy areas must have been at a minimum.

"The vegetation inhabited by the mammoth fauna can be shown to have consisted of open steppe on the water sheds and gallery forest and shrub thickets in the valleys. Most of the species comprising the mammoth fauna, including the mammoth itself, horse, rhinoceros, northern saiga, Baikal yak, bison, bighorn sheep, musk ox, longtailed souslik, marmot, and cave lion, are or were inhabitants of open landscapes. Grasses predominated in the diet of the mammoths and of most of the ungulates." (1982:277, 278).

How many Animals

The animals of the mammoth fauna in northeastern Siberia have died out at the end of the late Pleistocene, about 10 000 years ago. They have perished up there, when the cold, dry late Pleistocene changed over into the warm, wet Holocene, N. K. Vereshchagin concludes. The many bones and tusks of the woolly mammoth, which N. K. Vereshchagin has studied, do belong to the Würm III stage, the last part of the Ice Age. The mammoth bones do belong to the late form of the woolly mammoth. Also the many bones of the horses and bison up there, do belong to the late forms of these kinds of animals.

How many large animals have lived on this mammoth steppe in north-eastern Siberia between the Yana and Kolyma during the last part of the late Pleistocene? How many animals have lived there per square kilometer?

In the coastal lowland between the Yana and the Kolyma, about 550 000 tons of tusks are buried. That is, on the continental shelf, now flooded by the Arctic Ocean. And on the present lowland between the Yana and Kolyma, 150 000 tons of tusks are buried in the frozen ground. That are together 700 000 tons of tusks. The average mammoth tusk weighs 30 kg, as Prof. N. K. Vereshchagin reports. Each mammoth has two tusks. Hence, these 700 000 tons of tusks do represent 11 666 667 woolly mammoths.

The former mammoth steppe on the continental shelf, now submerged, is about 1 000 km long and 550 km wide. And the present coastal plain, between the Yana and Kolyma, is 1000 km long and 300 km wide. That is altogether: 850 000 km² of mammoth steppe. Thus, there were 13.7 woolly mammoths per square kilometer, or rounded up: 14 mammoth/km². This includes also small mammoth calves.

But on the northern mammoth steppe, not only these herds of woolly mammoths were grazing. In Alaska/Yukon and northern Siberia, the steppe-bison and the horse were usually the most numerous hoofed animals. Reindeer and muskox usually made up there only a few per cent of the individuals of the mammoth fauna. So, we must ask ourselves: How many animals have lived then altogether during the last part of the late Pleistocene in northeastern Siberia? That is, on a zonal steppe, some 1000 km long and 850 km wide, with its total area of about 850 000 km²?

We are only able to estimate this roughly, since the exact percentage of the individuals of the different kinds of hoofed animals of the mammoth fauna varied a little from place to place. Usually, the steppe-bison was the most numerous one, sometimes it was the horse. Reindeer and muskox made up only a few per cent of the total number of individuals of the mammoth fauna. Reindeer and muskox were not adapted then to an arctic tundra, because there was then no arctic tundra yet in northern Siberia. The arctic tundra, forest-tundra and taiga, as we know them now, have come there into being at the beginning of the Holocene. Hence, also the reindeer and the muskox on the Mammoth steppe were steppe animals, not tundra animals. They were also adapted then to the plants and the climate of the zonal steppe and forest-steppe.

Professor R. Dale Guthrie, at the University of Alaska at Fairbanks, has studied the bones of the mammoth fauna from 4 creeks in Central Alaska near Fairbanks, where placer-gold is being mined: at Fairbanks Creek, Engineer Creek, Cripple Creek, and Gold Hill. The average of the bones of late Pleistocene mammals from these 4 creeks, as published by him in 1968, is: Giant bison 50% individuals, horse 32.6%, mammoth 6.4%, reindeer 4.3% and muskox 2.5% individuals. – From this we can estimate now the total number of these five species of hoofed animals from the mammoth steppe between the Yana and Kolyma in northern Siberia:

The number of mammoth individuals , with its 6.4% is then 11 666 667 woolly mammoths. The steppe-bison, with its 50% individuals, is then 91 145 836 bison. And the horse, making up 32.6% of the individuals of the late Pleistocene mammoth fauna, is then 59 427 085 horses. The reindeer, with 4.3% individuals, has then 7 838 542 reindeer, and the muskox, with 2.5% individuals, has 4 557 292 muskoxen. Altogether there have lived then on the mammoth steppe, between Yana and Kolyma, 174 635 422 large mammals (woolly mammoths, steppe-bison, wild horses, reindeer and muskoxen).

 

How many per Square Kilometer

How many of these five kinds of hoofed animals have lived then on this late Pleistocene mammoth steppe per square kilometer?

The mammoth steppe between Yana and Kolyma was about 1000 km long and 850 km wide. That are 850 000 km². Thus, 205 animals (mammoth, bison, horse, reindeer and muskox) have lived there on each square kilometer. 250 large mammals/km² is many times more, than the number of large animals, which are living now in the Far North.

Someone might object now and say: But could these many bones and tusks not have come from many tens or even hundreds of thousands of years of the Pleistocene? – That is a serious argument? Is it valid? – No! – And why not? Because bones and tusks do disappear very quickly, also in the Far North. Most of them are not preserved. They have gone back to the dust. Only a very few are preserved, due to special conditions. So it is not normal at all that many millions of bones and tusks, and even whole bodies have been preserved till now. – Why? – Why have they not also returned to the dust within a few years, like the millions of bones of the other large mammals, which have lived up there before them, during hundreds of thousands of years?

The answer: Because most of these millions of woolly mammoths, steppe bison, horses, reindeer and muskoxen have died there at the same time and from the same cause. They have perished there at the same time, within one or at the most within a few days. The few bones, which might have been preserved from earlier times, will not affect this conclusion.

We might remember here, what Professor N. K. Vereshchagin said about the animals, dying now in northeastern Siberia. He said: "In general, skulls and other bones disappear rather quickly through the action of rodents, fungus, sun and rain." And at a loess deposition of 2-3 cm per year, "it would have taken 20-30 years to cover a mammoth, during which time the bones and tusks would have been almost entirely destroyed by atmospheric processes." (1974:6).

Also in the damp Tropics, the carcass of a large mammal very quickly disappears. Also the carcass of an elephant. Henry H. Howorth was President of the Royal Archaeological Institute. He states in his book The Mammoth and the Flood, published in London in 1887, on page 174: "Sir Emerson Tennent’s work on Ceylon. He will be everywhere accepted as probably the first authority on the life-history of the elephant: ‘Frequenters of the forrest with whome I have conversed whether Europeans or Singhalese, are consistent in their assurance that they have never found the remains of an elephant which has died a natural death.’"

And Professor R. Dale Guthrie states in his book Frozen Fauna of the Mammoth Steppe (1990:70-72): "Very few bones are preserved as fossils. The most common opportunity for preservation is a basic or calcareous environment. For this reason, limestone caves are our most important source for fossil bones. Without limestone caves the Pleistocene record of mammals would be meager. Caves buffer seasonal fluctuations in temperature and moisture, and their flood sediments are seldom acidic. To create most fossils, a bone must be covered so that aerobic decomposers cannot feed on the organic parts. Alkaline ponds and stream oxbows provide such conditions. Bones submerged in the mud of a pond or lake edge are likely to be preserved."

And in the text below the remains of a dead African elephant (Fig. 2.21 in his book), he says: "Few animals become fossils. This elephant died a natural death away from depositional environments out in the open African savanna. Most easily edible parts have been removed by scavengers. Only the thick dried hide and bones remain. The ears, feet, and tip of trunk are thin-skinned and were the first to be eaten. Eventually, what remains will be scattered by hyenas, but it is unlikely that any portion will become fossilized. That is true for most large mammals."

"Most conditions that produce fossils, preserve, at best, only bones. In very arid regions soft body parts occasionally become so dehydrated that decomposers cannot live and multiply; shrivelled mummies are the result. Preservation of Pleistocene fossils in parts of the unglaciated far north is exquisite, but we are only beginning to understand why so many fossils were preserved in Beringia. The cartoons showing woolly mammoth frozen in clear glacier ice misrepresent where mammies are found – they occur in silt deposits across unglaciated portions of the north. Mummification is not just a matter of freezing; carcasses must be buried by some rapid process. The geology of Beringian deposits and the fossils themselves can tell us how this usually happened.

"Like all ground cover in interior Alaska, except for high-alpine talus and river bars, solifluction lobes are thoroughly vegetated. Bones lying in such a vegetation mat are rapidly incorporated by plant overgrowth (usually by moss), then leached and destroyed by root acids. The rate of movement of solifluction lobes is not fast enough to incorporate many bones. Additionally, only a small margin of the solifluction lobe would work to cover bones in any one year. It is difficult to imagine a large mammoth bone or skull being incorporated intact. Solifluction movement would take several decades to cross the specimen, leaving one end decomposed, which is not the case with most Beringian fossils. One has to invoke a different, rapid depositional environment for large mammal mummies, and there seems to be a continuum between mummies and the smallest bones.

"It seems more accurate to say that there are few modern analogues to the downslope silt movement that occurred in the Pleistocene. We should imagine a different soil surface from the present thick layer of moss, lichen, or partially decomposed plants. Today, any silt that begins to move downslope is immediately filtered out and the water runs clean. Evidence from an array of studies suggests an incomplete surface cover for Pleistocene soils...

"During the Pleistocene, however, there seems to have been frequent transport of exposed silt downslope (Wu 1984). But during heavy rain or rapid snowmelt, enormous quantities could be moved over a short time. As previously mentioned, silt has the ability to get into suspension easily and to remain suspended as long as there is water movement. Once movement slows, silt particles come out of suspension and are deposited as fans or bars. I can imagine silt washing downslope during the Pleistocene, varying from broad sheets to channeled streams flushing over their banks." Guthrie, R. D. (1990:74, 75).

"Hamilton, Craig and Sellmann (1988) presented another interpretation of interior Alaskan silts, based on their work in the Fox permafrost tunnel (near Fairbanks). They think silt was deposited by two processes – reworked slow accretion of wind-born dust and massive redeposition of this reworked loess – and propose that eolian accretion occurred during cold, drier, glacial episodes, while redeposition processes were active only during wetter interstades and interglacials. These latter redeposited silts dominate the sedimentary record, in their estimation.

"I think this interpretation overlooks silt reworking during the glacials and overemphasizes interstade – interglacial contribution to the sedimentary record. There are simply too many well-preserved bones and large skulls that radiocarbon date to full glacial (Duvanny Yar). These could not be preserved by a few millimeters of annual eolian loess-fall; their preservation required large quantities of reworked silt. The frozen silt we find enclosing these glacial age bones is water saturated, not dry, drifted eolian material.

"I suggest that we are seeing two quite different Pleistocene patterns of silt redeposition in interior Alaska. In one, summer rains produced a broad sheetwash of silt in the millimeter and centimeter scales (on rare occasions much deeper), often over a short distance, with perhaps most not reaching the valley floor. In another, rapid spring snowmelt moved in more confined channels, probably taking large amounts of silt all the way to the valley floor. It is near these valley bottoms that one finds Pleistocene mammals buried." - Guthrie, R. D. (1990:78).