Thirty-Five Centuries Ago

Clock Unwound

We can determine the time necessary for lakes to collect mud deposited by melting glaciers, for rivers to build their deltas, for waterfalls to cut their channels and to remove the bedrock, for lakes without outlets to accumulate their salts. We can ascertain how much time has passed since beaches were raised, by the state of their shells, and the age of volcanic rocks by the amount of erosion. By counting the annual bands of clay and silt we may find out the number of years spent in their deposition. By studying the rings in old tree trunks we can determine the time of climatic changes as reflected in their growth. The remains of extinct and extant animals – their appearance, position on the ladder of evolution, and state of fossilization – enable us to establish their time of existence. By the content of radiocarbon in organic matter we may detect the time when an animal or plant died, and by the accumulation of fluorine in bones the length of time since burial. Finally, by studying artifacts and archaeologically determinable strata in the lands of antiquity, we may discover the time of deposit of associated animal or human remains; and by associated pollens of plants, a geochronological scale of climatic changes can be formulated even for areas where no archaeologically datable objects are found.

There are a few other ways of calculating geological time: by measuring the amount of sediment on the bottom of the ocean; by computing the amount of salt in the oceans and comparing it with the annual influx of salts from land; and, finally, by the analysis of rocks for their lead content as a product of decay of radioactive elements. But these ways, especially the last two, cannot be profitably applied for measuring time in thousands or tens of thousands of years; they were devised for reckoning time in millions of years. Of the methods used to find how much time has passed since the ice cover started to melt, the “varve” method, until recently, was thought to be fairly precise. This method was introduced by G. de Geer, who counted the annual bands of silt and clay (“varves”) deposited, coarse in summer and fine in winter, under the ice in the coastal lakes and rivers of Sweden, once covered by the glacial sheet of the Ice Age. De Geer calculated that it had taken about 5000 years to melt the ice cover from Schonen, at the southern tip of Sweden, to the place in the north where there are still glaciers in the mountains; In no place are there five thousand overlying varves; but De Geer looked for similar series or patterns of thick and thin varves from one lake to another, about fifteen hundred outcrops altogether, always with the thought that a varve series found high in the deposit of some southern lake would repeat itself closer to the bottom of a lake to the north.

Additional figures used in De Geer’s evaluation of the time that passed since the end of the Ice Age are of a more hypothetical nature. For the preceding period, the time allegedly needed for the ice to retreat all the way, from Leipzig to southern Sweden, where no varves are found, De Geer offered, as a surmise, a span of 4000 years. Then he surmised further that the end of the melting of the ice cover coincided with the beginning of Neolithic time, which he placed 5000 years ago, thus arriving at the final figure of 14,000 years, or 12,000 years before the present era. The area of Stockholm was freed from ice about 10,000 years ago. Other scientists freely interpreted De Geer’s data as indicating that the ice cover in Europe started to melt 25,000 or even 40,000 years ago.¹ The method, when applied to North America, also gave the figure the explorers looked for, namely 35,000 to 40,000 years; in this estimate great stretches of land without varves in them were freely evaluated as to the time in question.

De Geer applied his method of identifying synchronical varves to countries as far apart as Sweden, Central Asia, and South America. His telechronology was objected to on the ground that a dry phase in Scandinavia may not necessarily have coincided with a dry phase in the Himalayas or in the Andes, and that therefore the telechronology was built on an erroneous assumption.² But the method as applied to northern Europe or North America was hailed as a most exact geological time clock: The summing up of varves from one dried-out lake to another is a delicate process and often subjective appraisals replace an objective method; especially arbitrary are the estimates for intervening stretches of land where no varves are found.

In 1947 an ingenious new method of investigating the age of organic remains was developed by W. F. Libby of the University of Chicago. The radiocarbon dating method is based on the fact that when cosmic rays hit the upper atmosphere they break the nitrogen atoms into hydrogen (H) and radiocarbon (C14), or carbon with two extra electrons, therefore unstable, or radioactive.

The radiocarbon is mixed with the atmospheric carbon and as carbon dioxide it is absorbed by plants; it enters the animal body that feeds on plants and also the carnivore that feeds on other animals. Thus all animal and plant cells as long as they live contain approximately the same amount of radiocarbon; when death comes, no new radiocarbon is assimilated and the radiocarbon present in the remains undergoes the process of decay, as every radioactive substance does. After 5568 years only half of the radiocarbon remains; after another 5568-year period only half of the half, or a quarter of the original content in the organic body, remains. A sample undergoing analysis – a piece of wood or skin – is burned to ashes and its radiocarbon content is determined by a Geiger counter. This method claims accuracy for organic objects between 1000 and 20,000 years old; bones and shells are unsuitable materials because organic carbon is easily lost in the process of fossilization, often being replaced by carbon in ground water and by mineral salts.

The first important result of the radiocarbon dating method in glacial chronology was a radical reduction of the terminal date of the Ice Age. It was shown that ice, instead of retreating 30,000 years ago, was still advancing 10,000 or 11,000 years ago.³ This conflicts strongly with the figures arrived at by the varve method concerning the final phase of the Ice Age in North America.⁴

Even this great reduction of the date of the end of the Ice Age is not final. Radiocarbon analysis, according to Professor Frederick Johnson, chairman of the committee for selection of samples for analysis,⁵ revealed “puzzling exceptions.” In numerous cases the shortening of the time schedule was so great that, as the only recourse, Libby assumed a “contamination” by radiocarbon. But in manyother cases “the reason for the discrepancies cannot be explained.” Altogether the method indicates that “geological developments were speedier than formerly supposed.”⁶

H. E. Suess of the United States Geological Survey reported recently that wood found at the base of interbedded blue till, peat, and outwash of drift, and ascribed by its finder to the Late Wisconsin (last) glaciation, is, according to radiocarbon analysis, but 3300 years old (with a margin of error up to two hundred years both ways), or of the middle of the second millennium before the present era. Still more recently Suess and Rubin reported that “a glacial advance in the mountains of western United States was determined to have occurred about 3000 years ago.”⁷

Already there is an accumulation of similar results that do not fit into the accepted scheme, even if the Ice Age is brought as close to our time as 10,000 years. Professor Johnson says: “There is no way at the moment to prove whether the valid dates, the ‘invalid ones,’ or the ‘present ideas’ are in error.”⁸ He says also: “Until the number of measurements can be increased to a point permitting some explanation of contradictions with other apparently trustworthy data, it is necessary to continue to form judgments concerning validity by a combination of all available information.”

With this idea in mind, I offer in the following sections a review of the results of several other methods of time measurement, especially as regards the dating of the last glaciation.

Libby recognizes that the exactness of his method is dependent on two assumptions. The first is that for the last 20,000 or 30,000 years the amount of cosmic radiation reaching our atmosphere remained constant; the other is that the quantity of water in the oceans has not changed in the same period of time. Actually only a minor part of the radiocarbon created by cosmic rays is absorbed by plants and animals, the so-called biosphere; a still smaller part is present in the atmosphere; the largest share is absorbed by the ocean.

Libby stressed the significance of these factors. It transpires that if there were cosmic catastrophes in the past cosmic radiation could have reached the earth at a different intensity; and in a future book I intend to show that the waters of the oceans and their salts were increased substantially in a recent geological age.

Bearing in mind these limitations, I confidently expect that in the field of geology more and more “puzzling” results of radiocarbon tests will compel a full-scale revision of the dating of the glacial periods.⁹

The Glacial Lake Agassiz

Lake Agassiz, the largest glacial lake of North America, once covered the region at present occupied by Lake Winnipeg, Lake Manitoba, a number of other lakes in Canada, and parts of the North Central States of the United States. It exceeded the aggregate area of the five Great Lakes tributary to the St. Lawrence River. It was formed when the ice of North America melted. Study of its sediment, however, disclosed that its entire duration had been definitely less than one thousand years, a measure of time unexpectedly short; this indicates also that the glacial cover melted under catastrophic conditions. Warren Upham, the American glaciologist, wrote:
“The geologic suddenness of the final melting of the ice-sheet, proved by the brevity of existence of its attendant glacial lakes, presents scarcely less difficulty for explanation of its causes and climatic conditions than the earlier changes from mild and warm preglacial conditions to prolonged cold and ice accumulation.”¹⁰

Not only was the life of the glacial Lake Agassiz measured in hundreds of years and the melting of the continental ice cover that gave rise to this lake of short duration but this melting must have taken place only recently: the erosion on the shores of Lake Agassiz indicates that it existed only a short time ago. Upham also recognized that the shoreline of the extinct lake is not horizontal, which indicates that the warping too occurred recently.

Although this study of Lake Agassiz by Upham is over fifty years old, its conclusions have never been challenged. He also stated:

“Another indication that the final melting of the ice sheet upon British America was separated by only a very short interval, geologically speaking, from the present time is seen in the wonderfully perfect preservation of the glacial striation and polishing on the surface of the more enduring rocks. … It seems impossible that these rock exposures can have so well withstood weathering in the severe climate of those northern regions longer than a few thousand years at the most.”¹¹

Upham realized and stressed that “these measures of time” are “surprisingly short, whether we compare them on the one hand with the period of authentic human history or on the other hand with the long record of geology.”
How it started, how it ended – all appears enigmatic; what is clear is that great changes took place but a few thousand years ago, under catastrophic conditions.

Niagara Falls

When Lyell, on his trip to the United States, visited Niagara Falls, he talked with someone who lived in the vicinity and was told that the falls retreat about three feet a year. Since the natives of a country are likely to exaggerate, Lyell announced that one foot per annum would be a better figure. From this he concluded that over thirty-five thousand years were necessary, from the time the land was freed from the ice cover and the falls started their work of erosion, to cut the gorge from Queenston to the place it occupied in the year of Lyell’s visit. Since then this figure has often been mentioned in textbooks as the length of time from the end of the glacial period.

The date of the end of the Ice Age was not changed when subsequent examination of records indicated that since 1764 the falls had retreated from Lake Ontario toward Lake Erie at the rate of five feet per year, and that, if the process of wearing down the rock had gone on at the same rate from the time of the retreat of the ice cover, seven thousand years would have been sufficient to do the work.

However, since in the beginning, when the ice melted and a swollen stream carried the detritus abrading the rock of the gorge, the erosion rate must have been much more rapid, the age of the gorge must be further reduced. According to G. F. Wright, author of TheIce Age in North America, five thousand years may be regarded as an adequate figure.¹² The erosion and sedimentation of the shores of Lake Michigan also suggest a lapse of time reckoned in thousands, but not tens of thousands, of years since the beginning of the process.¹³

In the 1920s, however, when borings were made for a railroad bridge, it was found that the middle part of Whirlpool Rapids Gorge of Niagara Falls contained a thick deposit of glacial boulder clay, indicating that it had been excavated once, had been filled with drift, and then partly re-excavated by the falls in post-glacial times. 14 While the question of the age of the falls thus becomes complicated, the discovery shows that the post-glacial period was of much shorter duration than generally assumed, even if the rate of retreat of the falls is reduced to the minimum figure of under four feet per year, as observed in more recent years. R. F. Flint of Yale writes:

“We are obliged to fall back on the Upper Great Gorge, the uppermost segment of the whole gorge, which appears to be genuinely post-glacial. Redeterminations by W. H. Boyd showed the present rate of recession of the Horseshoe Falls to be, not five feet, but rather 3.8 feet, per year. Hence the age of the Upper Great Gorge is calculated as somewhat more than four thousand years – and to obtain even this [low] figure we have to assume that the rate of recession has been constant, although we know that discharge has in fact varied greatly during post-glacial times.”¹⁵

If due allowance is made for this last factor, the age of the Upper Great Gorge of Niagara Falls would be somewhere between 2500 and 3500 years. It follows that the ice retreated in historical times, somewhere between the years 1500 and 500 before the present era.

The Rhone Glacier

The lifetime of a glacier is determined by measuring the detritus deposited by the melting ice. Albert Heim, the Swiss naturalist, estimated the age of the glacial river Muota that flows into Lake Lucerne as sixteen thousand years. F. A. Forel, another Swiss naturalist, undertook an evaluation of the detrital mud deposited by the Rhone Glacier on the bottom of Lake Geneva. He arrived at a figure close to twelve thousand years as the span of time necessary for the mud and detritus to have been deposited on the bottom of the lake, or from the height of the Ice Age to the present. Forel’s result actually signifies that the Rhone Glacier, which feeds the river and the lake, is evidence of the short duration of the post-glacial period, or even of the entire Ice Age if the origin of the lake goes back to the first glacial period. These estimates, when announced, were much lower than expected.

The eminent French geologist of the beginning of this century, and a colleague of Heim and Forel, A. Cochon de Lapparent, arrived at an even more radical result. In the time of its greatest expansion, the Rhone Glacier reached from Valais to Lyons. De Lapparent took the average figure of progression as seen today on larger glaciers. Mer de Glace, a glacier on Mont Blanc, moves fifty centimeters in twenty-four hours. Moving at a comparative velocity, the Rhone Glacier, when expanding, would have required 2475 years to progress from Valais to Lyons. Then, comparing the terminal moraines, or stone and detritus accumulation, of several present day glaciers with the moraines left by the Rhone Glacier at its maximum expansion, De Lapparent again arrived at a figure of about 2400 years. He also concluded that the entire Ice Age was of very short duration. To this another geologist, Albrecht Penck, objected.¹⁶ His objection was based not on a disproval of the above figures, but on a claim that great evolutionary changes took place during the consecutive interglacial periods. The divergence of opinion between them was so great that hundreds of thousands of years in Penck’s scheme were reduced to mere thousands of years in De Lapparent’s calculations. Penck estimated the duration of the Ice Age, with its four glacial and three interglacial periods, as one million years. Each of the four glaciations and deglaciations must have consumed one hundred thousand years and more. The argument for his estimate is this: How much time was necessary to produce the changes in nature, if no catastrophes intervened? And how long would it take to produce changes in animals by means of a process that in our own day is so slow, as to be almost imperceptible?

Carl Schuchardt, in his book, Alteuropa, warned his colleagues not to turn deaf ears to voices like that of De Lapparent. Let us assume that the geological processes were always as they are now. In Ehringsdorf near Weimar there is a tufa layer in which, during the entire last interglacial period, calcium was deposited. “But should we even assume all kinds of imaginable causes that would have retarded the deposition of calcium so as to make it ten times as slow as at present, still we would have only 3000 years and not 100,000!”¹⁷

If we follow the principle of quantitative analysis and accept De Lapparent’s figure as approximately correct, the maximal extension of the Rhone Glacier dates from a point well within the bounds of human history.
The recent field work in the Alps actually revealed that numerous glaciers there are no older than 4000 years. This startling discovery made the following statement necessary: “A large number of the present glaciers in the Alps are not survivors of the last glacial maximum, as was formerly universally believed, but are glaciers newly created within roughly the last 4000 years.”¹⁸

The Mississippi

The Mississippi carries yearly in its stream many billions of tons of detritus, a large part of which is deposited in the delta. As early as 1861, Humphreys and Abbot calculated the age of the Mississippi by evaluating the detritus borne by it and the sediment deposited in the delta. They arrived at the low figure of 5000 years as the age of the delta, its birth thus being related to about the year 2800 before the present era.¹⁹ However, when at the close of the Ice-Age the ice cover melted in the north, multitudinous streams must have carried an enormous amount of detritus into the Mississippi and its tributary, the Missouri, and for this reason the above figure, if otherwise properly calculated, must be appreciably reduced. It is assumed that when the continental ice started to melt and the Great Lakes became swollen, but the St. Lawrence was still blocked by ice, the water of the basin emptied to a great extent into the Gulf of Mexico through the Mississippi.

The Falls of St. Anthony on this stream at Minneapolis have excavated a long gorge by removing the bedrock. In the 1870s and 1880s N. H. Winchell made this falls the subject of a study. Comparing topographical maps covering two hundred years, he concludedthat the falls had retreated 2.44 feet yearly. If this was the constant rate of retreat, the falls must have started 8000 years ago.²⁰ But here, too, a larger stream carrying abundant detritus, which abraded the bedrock, must have flowed when the ice cover melted. J. D. Dana, studying the area, of Lake Champlain and of the Northeastern states in general, came to the conclusion that prodigious floods of almost unimaginable magnitude accompanied the melting of the ice cover: in the lower part of the Connecticut River the floods rose two hundred feet above the present high-water mark.²¹ And if this is true for those regions, it must be true also for the valley of the Mississippi. Consequently the gorge of the Falls of St. Anthony must be of more recent date than Winchell calculated, though even his figure was regarded as much too low.

The protracted discussion of the results derived from the exploration of Niagara and St. Anthony falls demonstrated the need for yet another area of investigation, preferably the delta of a stream fed by a still existing glacier that could be carefully studied. For that purpose the delta of the Bear River was selected (a stream from a melting glacier that enters the Portland Canal on the Alaska-British Columbia border). On the basis of three earlier accurate surveys made between the years 1909 and 1927, G. Hanson in 1934 calculated with great exactness the annual growth of the delta through deposited sediment. At the present rate of sedimentation the delta is estimated to be “only 3600 years old.”²² The glacier that feeds the Bear River was formed and began to melt in the middle of the second millennium before the present era.

Fossils in Florida

On the Atlantic coast of Florida, at Vero in the Indian River region, in 1915 and 1916, human remains were found in association with the bones of Ice Age (Pleistocene) animals, many of which either became extinct, like the saber-toothed tiger, or have disappeared from the Americas, like the camel.

The find caused immediate excitement among geologists and anthropologists. Beside the human bones pottery was found, as well as bone implements and worked stone. Ales Hrdlicka, of the Smithsonian Institution of Washington, D. C., a renowned anthropologist (who generally opposed the view that man existed in America in the Ice Age), wrote that the “advanced state of culture, such as that shown by the pottery, bone implements, and worked stone brought from a considerable distance, implies a numerous population spread over large areas, acquainted thoroughly with fire, with cooking food, and with all the usual primitive arts”; the human remains and relics could not be of an antiquity “comparable with that of fossil remains with which they are associated.”²³ He also published the opinion of W. H. Holmes, head curator of the Department of Anthropology of the United States National Museum, who investigated the pottery obtained by Hrdlicka from Vero. These were bowls “such as were in common use among the Indian tribes of Florida.” When compared with vessels from Florida earth mounds, “no significant distinction can be made; in material, thickness of walls, finish of rim, surface finish, color, state of preservation, and size and shape,” the vessels “are identical.”

There thus appears “not the least ground in the evidence of the specimens themselves for the assumption that the Vero pottery pertains to any other people than the mound-building Indian tribes of Florida of the pre-Columbian time.”

But the bones of man and his artifacts (pottery) were found among the extinct animals. The discoverer of the Vero deposits, E. H. Sellards, state geologist of Florida and a very capable paleontologist, wrote in the debate that ensued: “That the human bones are fossils normal to this stratum and contemporaneous with the associated vertebrates is determined by their place in the formation, their manner of occurrence, their intimate relation to the bones of other animals, and the degree of mineralization of the bones.” This “degree of mineralization of the human bones is identical with that of the associated bones of the other animals.” In his view the evidence obtained “affords proof that man reached America at an early date and was present on the continent in association with a Pleistocene [Ice Age] fauna.”²⁴ Anthropologists of the Hrdlicka school would not accept this, claiming a late arrival of man on the American continent, and the presence of pottery was in their view proof of a late date for the human bones. The human skulls, though fossilized, did not differ from the skulls of the Indians of today.

In 1923 – 29, thirty-three miles north of Vero, in Melbourne, Florida, another such association of human remains and extinct animals was found, “a remarkably rich assemblage of animal bones, many of which represent species which became extinct at or after the close of the Pleistocene [Ice Age] epoch.”²⁵ The discoverer, J. W. Gidley, of the United States National Museum, established unequivocally that in Melbourne – as in Vero – the human bones were of the same stratum and in the same state of fossilization as the bones of the extinct animals. And again human artifacts were found with the bones. The “projectile points, awls, and pins” found with the human bones at Melbourne as well as at Vero are of the same workmanship as those unearthed in early Indian sites, two thousand of which are known in the area.

All these and other considerations of an anthropological as well as geological nature, being summed up, prove, in the opinion of I. Rouse, a recent analyst of the much-debated fossils of Florida, that “the Vero and Melbourne man should have been in existence between 2000 B.C. and the year zero A.D.”²⁶ This does not solve the problem of the association of extinct animals and man who lived between two and four thousand years ago, in the second and first millennia before the present era.

There is no proper way out of this dilemma, other than the assumption that now extinct animals still existed in historical times and that the catastrophe which overwhelmed man and animals and annihilated numerous species occurred in the second or first millennium before the present era.

The geologists are right: the human remains and artifacts of Vero and Melbourne in Florida are of the same age as the fossils of the extinct animals.

The anthropologists are equally right: the human remains and artifacts are of the second or first millennium before the present era.

What follows? It follows that the extinct animals belonged to the recent past. It follows also that some paroxysm of nature heaped together these assemblages; the same paroxysm of nature may have destroyed numerous species so that they became extinct.

Lakes of the Great Basin and the End of the Ice Age

The Sierra Nevada chain rises between the Great Basin to the east and the Pacific, cutting off the drainage to the ocean. Abert and Summer lakes in southern Oregon have no outlets. They are regarded as remnants of a once large glacial lake, Chewaucan. W. van Winkle of the United States Geological Survey investigated the saline content of these two lakes and wrote: “A conservative estimate of the age of Summer and Abert Lakes, based on their concentration and area, the composition of the influent waters, and the rate of evaporation, is 4000 years.”²⁷ If this conclusion is correct, the post-glacial epoch is no longer than 4000 years. Startled at his own result, Van Winkle conjectured that salt deposits of the early Chewaucan Lake may be hidden beneath the bottom sediments of the present Abert and Summer lakes.

To the east of Sequoia National Park and Mount Whitney in California lies Owens Lake. It is supplied by the Owens River and it has no outlet. At some time in the past the surface level of the lake, because of a greater water supply, was so much higher that it overflowed its basin. H. S. Gale analyzed the water of the lake and of the river for chlorine and sodium and came to the conclusion that the river required 4200 years to supply the chlorine present in the lake and 3500 years to supply its sodium. Ellsworth Huntington of Yale found these figures too high, because no allowance was made for greater rainfall and “freshening of the lake” in the past, and consequently he reduced the age of the lake to 2500 years, which would place its origin not far from the middle of the first millennium before the present era.²⁸

Another vast lake of the past without an outlet to the sea was Lake Lahontan in the Great Basin of Nevada, which covered an area of 8500 square miles. As its water level fell, it split up into a number of lakes divided by a desert terrain. In the 1880s I. Russell of the United States Geological Survey investigated Lake Lahontan and its basin, and established that the lake was never completely dried out and that the present-day Pyramid and Winnemucca lakes north of Reno and Walker Lake southwest of it are the residuals of the older and larger lake.²⁹ He concluded that Lake Lahontan existed during the Ice Age and was contemporaneous with the different stages of glaciation of that age. He also found bones of Ice Age animals in the deposits of the ancient lake.

More recently, Lahontan and its residual lakes were explored anew by J. Claude Jones, and the results of his work were published as Geological History of Lake Lahontan by the Carnegie Institution of Washington.³⁰ He investigated the saline content of Pyramid and Winnemucca lakes and of the Truckee River that feeds them. He found that the river could have supplied the entire content of chlorine of these two lakes in 3881 years. “A similar calculation, using sodium instead of chlorine, gave 2447 years necessary.” Jones’s careful work led him to agree with Russell that Lake Lahontan never fully dried up and that the existing lakes are its residuals.

But these conclusions require that the age of the mammals of the Ice Age, found in the deposits of Lake Lahontan, be not greater than that of the lake. This means that the Ice Age ended only twenty-five to thirty-nine centuries ago. Jones checked the figures obtained from the rate of accumulation of chlorine and sodium as brought in by the Truckee River, with other methods, such as the accumulation of chlorine in lakes during the thirty-one years that had passed since the analysis made by Russell, and also the rate of concentration of salts by evaporation, and each time reached the result that the entire history of Pyramid and Winnemucca lakes “is within the last 3000 years.”³¹

Bones of horses, elephants, and camels, animals that became extinct in the Americas, were found in the Lahontan sediments, as well as a spear point of human manufacture.³² When a branch of the Southern Pacific Railroad was laid through Astor Pass, a large gravel pit of Lahontan age was opened, and J. C. Merriam of the University of California identified among the bones the skeletal remains of Felix atrox, a species of lion found also in the asphalt pit of Rancho La Brea, as well as a species of horse and camel, also found in La Brea.³³ “All of these forms are now extinct and neither camels nor lions are found on this continent as a part of the present native fauna.”³⁴ The similarity of the fauna of the asphalt pits of La Brea and the deposits of Lake Lahontan led Merriam to decide that they were contemporaneous.

On the basis of his analyses Jones came to the conclusion that the extinct animals lived in North America into historical times. This was an unusual statement and it was opposed at first on the ground that his interpretation of his observations was “obviously erroneous, since [it] led him to the conclusion that the mastodon and the camel lived on in North America into historical times.”³⁵ But this is an argument of a preconceived nature, not based on findings of field geology. Either the Ice Age animals survived the Ice Age, or some of the vicissitudes of the Ice Age occurred in historical times.