Two rather curious pieces of evidence suggest that the lithosphere may be in motion at the present time. We have two observations of a movement of the North Pole with reference to the earth’s surface. The first of these is cited by Deutsch (111a:37-38) on the authority of Munk and MacDonald. It suggests that the North Pole moved 10 feet in the direction of Greenland along the meridian of 45° West Longitude during the period from 1900 to 1960. This (according to Deutsch) would be at a rate of 6 centimeters (about two and a half inches) a year. The other finding, cited by Markowitz (292a), based on later data, suggests that the pole moved about 20 feet between 1900 and 1968 along the meridian of 65° West Long., and that it is now moving at the rate of about 10 centimeters (4 inches) a year. The difference between the two longitudes may not be particularly important, as the angular difference so near the pole is so small, but the difference in the two rates of motion may be very important. In the first place, it may be noted that a speed of 10 centimeters a year is two or three times the maximum speed usually estimated for subcrustal convection currents. This appears to imply that the displacement indicated as now occurring is not powered by convection currents. There is the suggestion of another mechanism at work.
A second point, possibly even more interesting, is that if both these observations were accurate when made, as we have every right to expect (in view of the eminence of the scientists involved), then we may have here evidence of a geometrical acceleration of the rate of motion. If the pole moved 10 feet between 1900 and 1960, but 20 feet between 1900 and 1968, then it moved 10 feet between 1960 and 1968, which would suggest an acceleration by a factor of about 8. The mechanism I have suggested above is based on a formula involving the geometrical progression of centrifugal effects, that is, the formula for calculating centrifugal force, which is a simple one (see p. 338).
THE FAILURE TO EXPLAIN THE ICE AGES
The evidence for displacements of the earth’s outer shell is scattered over many parts of the earth and comes from several fields of science. It would not be justifiable to disregard this other evidence simply because the evidence from geomagnetism seems so strong. No other field furnishes so dramatic a confirmation of displacements as glacial geology. Here we review the facts that have led geologists, at various times during the last hundred years, to consider ideas of polar shift.
A little more than a hundred years ago people were astonished at the suggestion that great ice sheets, as much as a mile thick, had once lain over the temperate lands of North America and Europe. Many ridiculed the idea, as happens with new ideas in every age, and sought to discredit the evidence produced in favor of it. Eventually the facts were established regarding an ice age in Europe and in North America. People later accepted the idea of not one but a series of ice ages. As time went on evidences were found of ice ages on all the continents, even in the tropics. It was found that ice sheets had once covered vast areas of tropical India and equatorial Africa.
From the beginning, geologists devoted much attention to the possible cause of such great changes in the climate. One theory after another was proposed, but, as the information available gradually increased, each theory was found to be in conflict with the facts, and as a consequence had to be discarded. In 1929, Coleman, one of the leading authorities on the ice ages, wrote :
Scores of methods of accounting for ice ages have been proposed, and probably no other geological problem has been so seriously discussed, not only by glaciologists, but by meteorologists and biologists : yet no theory is generally accepted. The opinions of those who have written on the subject are hopelessly in contradiction with one another, and good authorities are arrayed on opposite sides ... (87:246).
Recent writers, such as Daly (98:257), Umbgrove (419:285), and Gutenberg (194:205), agree that the situation described by Coleman is essentially unchanged. In January, 1953, Professor J.K. Charlesworth, of Queen’s University, Belfast, expressed the opinion that
The cause of all these changes, one of the greatest riddles in geological history, remains unsolved; despite the endeavors of generations of astronomers, biologists, geologists, meteorologists and physicists, it still eludes us (75:3).
A volume on climatic change, edited by Dr. Harlow Shapley (375), while suggesting minor refinements for various older theories, proposes no new ones and in no way modifies the general effect, which is that down to the present time the theorizing about the causes of ice ages has led nowhere.
One problem that writers on the ice ages have attempted to solve, sometimes in rather fantastic ways, but without success, is that of the wrong location of the great ice caps of the past. These ice caps have refused to have anything to do with the polar areas of the present day, except in a quite incidental fashion.
Originally it was thought that in glacial periods the ice caps would fan out from the poles, but then it appeared that none of them did so, except the ones that have existed in Antarctica. Coleman drew attention to the essential facts, as follows :
In early times it was supposed that during the glacial period a vast ice cap radiated from the North Pole, extending varying distances southward over seas and continents. It was presently found, however, that some northern countries were never covered by ice, and that in reality there were several more or less distinct ice sheets starting from local centers, and expanding in all directions, north as well as east and west and south. It was found, too, that these ice sheets were distributed in what seemed a capricious manner. Siberia, now including some of the coldest parts of the world, was not covered, and the same was true of most of Alaska, and the Yukon Territory in Canada; while northern Europe, with its relatively mild climate, was buried under ice as far south as London and Berlin; and most of Canada and the United States were covered, the ice reaching as far south as Cincinnati in the Mississippi Valley (87:7-9).
With regard to an earlier age (the Permo-Carboniferous), Coleman emphasized that the locations of the ice caps were even further out of line :
Unless the continents have shifted their positions since that time, the Permo-Carboniferous glaciation occurred chiefly in what is now the southern temperate zone, and did not reach the arctic regions at all (87:90).
He is much upset by the fact that this ice age apparently did not affect Europe :
Unless European geologists have overlooked evidence of glaciation at the end of the Carboniferous or at the beginning of the Permian, the continent escaped the worst of the glaciation that had such overwhelming effects on other parts of the world. A reason for this exemption is not easily found (87:96).
One of the most extraordinary cases is that of the great ice sheet that covered most of India in this period. Geologists are able to tell from a careful study of the glacial evidences in what direction an ice sheet moved, and in this case the ice sheet moved northward from an ice center in southern India for a distance of 1,100 miles. Coleman comments on this as follows :
Now, an ice sheet on level ground, as it seems to have been in India, must necessarily extend in all directions, since it is not the slope of the surface it rests on that sets it in motion, but the thickness of the ice towards the central parts. ...
The Indian ice sheet should push southward as well as northward. Did it really push as far to the south of Lat. 17° as to the north ? It extended 1,100 miles to the Salt Range in the north. If it extended the same distance to the south it would reach the equator (87:110-11).
The great South African geologist A.L. du Toit pointed out that the ice caps of all geological periods in the Southern Hemisphere were eccentric as regards the South Pole, just as the Pleistocene ice caps were eccentric with regard to the North Pole (87:262). Is it not extraordinary that the Antarctic ice cap, which we can actually see because it now exists, is the only one of all these ice caps that is found in the polar zone ?
Coleman, who did a great deal of field work in Africa and India, studying the evidences of the ice ages there, writes interestingly of his experiences in finding the signs of intense cold in areas where he had to toil in the blazing heat of the tropical sun :
On a hot evening in early winter two and a half degrees within the torrid zone amid tropical surroundings it was very hard to imagine the region as covered for thousands of years with thousands of feet of ice. The contrast of the present with the past was astounding, and it was easy to see why some of the early geologists fought so long against the idea of glaciation in India at the end of the Carboniferous (87:108).
Some hours of scrambling and hammering under the intense African sun, in lat. 27° 5', without a drop of water, while collecting striated stones and a slab of polished floor of slate, provided a most impressive contrast between the present and the past, for though August 27th is still early Spring, the heat is fully equal to that of a sunny August day in North America. The dry, wilting glare and perspiration made the thought of an ice sheet thousands of feet thick at that very spot most incredible, but most alluring (87:124).
When these facts were established, geologists sought to explain them by assuming that, at periods when these areas were glaciated, they were elevated much higher above sea level than they are now.
Theoretically, even an area near the equator, if elevated several miles above sea level, would be cold enough for an ice sheet. What made the theory plausible was the well-known fact that the elevations of all the lands of the globe have changed repeatedly and drastically during the course of geological history. Unfortunately for those who tried to explain the misplaced ice caps in this way, however, Coleman showed that they reached sea level, within the tropics, on three continents: Asia, Africa, and Australia (87:129, 134, 140, 168, 183). At the same time, W.J. Humphreys, in his examination of the meterological factors of glaciation, made the point that high elevation means less moisture in the air, as well as lowered temperature, and is therefore unfavorable for the accumulation of great ice caps (231:612-13).
A widely accepted assumption with which contemporary geologists approach the question of ice ages is that the latter have occurred as the result of a lowering of the average temperature of the whole surface of the earth at the same time. This assumption has forced them to look for causes of glacial periods only in such factors as would tend to cool the whole surface of the earth at once. It has resulted in the assumption that glacial periods have always been simultaneous in the northern and southern hemispheres.
It is remarkable that this assumption has been maintained over a long period of time despite the fact that it is in sharp conflict with basic principles of physics in the field of meteorology. The basic conflict was brought to the attention of science at least seventy years ago; it has never been resolved. It consists essentially of the fact that glacial periods were periods of heavier rainfall in areas outside the regions of the ice sheets, so that this, together with the deep accumulations of ice in the great ice sheets, apparently must have involved a higher average rate of precipitation during ice ages. There is a great deal of geological evidence in support of this. Only recently, for example, Davies has discussed the so-called “pluvial” periods in Africa and has correlated them with the Pleistocene glacial periods (107).
Now, meteorologists point out that if precipitation is to he increased, there has to be a greater supply of moisture in the air. The only possible way of increasing the amount of moisture in the air is to raise the temperature of the air. It would seem, therefore, that to get an ice age one would have to raise, rather than lower, the average temperature. This essential fact of physics was pointed out as long ago as 1892 by Sir Robert Ball, who quoted an earlier remark by Tyndall :
... Professor Tyndall has remarked that the heat that would be required to evaporate enough water to form a glacier would be sufficient to fuse and transform into glowing molten liquid a stream of cast iron five times as heavy as the glacier itself (20:108).
William Lee Stokes has again called attention to this unsolved problem in an article entitled “Another Look at the Ice Age” in a statement that strongly suggests crust displacement :
Lowering temperatures and increased precipitation are considered to have existed side by side on a world-wide scale and over a long period in apparent defiance of sound climatological theory. Among the many quotations that could be cited reflecting the need for a more comprehensive explanation of this difficulty the following seems typical.
“In the Arequipa region [of Peru], as in many others in both hemi-pheres where Pleistocene conditions have been studied, this period appears to have been characterized by increased precipitation as well as lowered temperatures. If, however, precipitation was then greater over certain areas of the earth’s surface than it is at present, a corollary seems to be implied that over other large areas evaporation was greater than normal to supply increased precipitation, and hence in these latter areas the climate was warmer than normal. This seems at first to be an astonishing conclusion. ... We might propose the hypothesis that climatic conditions were far from steady in any one area, but were subject to large shifts, and that intervals of ameliorated conditions in some regions coincided with increased severity in others. The Pleistocene, then, may have been a period of sharper contrasts of climate and of shifting climates rather than a period of greater cold” (i95:815-16).
From a number of points of view, the foregoing passage is extremely remarkable. Stokes recognizes the fact that the basic assumption of contemporary geologists regarding the glacial periods is in conflict with the laws of physics. Then, in the passage he quotes, he draws attention to the implications, which if the theory of continental drift is rejected seem to point directly to crust displacement, for in what other way can we explain how one part of the earth’s surface was colder and another, at the same time, warmer than at present ?
One of the arguments that are advanced in support of the assumption of worldwide periods of colder weather (which remains the generally accepted assumption of glaciologists) has its basis in geological evidence purporting to prove that ice ages occurred simultaneously in both hemispheres. A decade ago, however, Kroeber pointed to the essential weakness of this geological evidence when he showed the difficulty of correlating stratified deposits of different areas :
... There is plenty of geologic evidence, in many parts of the earth, of changes of climates, especially between wet and dry areas; and some of these happened in the Pleistocene. But the correlation of such changes as they occurred in widely separated regions, and especially as between permanently ice-free and glaciated areas, is an intricate, tricky, and highly technical matter, on which the anthropological student must take the word of geologists and climatologists, and these are by no means in agreement. They may be reasonably sure of one series of climatic successions in one region, and of another in a second or third region; but there may be little direct evidence on the correspondence of the several series of regional stages, the identification of which then remains speculative (257:650).
At the time that Kroeber remarked on the difficulty of correlating climatic changes in different parts of the world, we were not yet in possession of the data recently provided by the new techniques of radiocarbon and ionium dating. The effect of these new data has been to shorten very greatly our estimate of the duration of the last North American ice age. This estimate has been reduced, in the last few years, from about 150,000 years to about 50,000 years. Now, if we adopt the view that ancient glaciations, of which we know little, may reasonably be considered to have been the results of the same causes that brought about the North American ice age, then we must grant that they, too, may have been of short duration. But if this is true, how is it possible to establish the fact that they were contemporary in the two hemispheres ? A geological period has a duration of millions of years. An ice age in Europe and one in Australia might both be, for example, of Eocene age, but the Eocene Epoch is estimated to have lasted about 15,000,000 years. We can discriminate roughly between strata dating from the early, middle, or late Eocene, but we have no way of pinpointing the date of any event in the Eocene. Even with the new techniques of radiodating now being applied to the older rocks, it is possible to determine dates only to within a margin of error of about a million years. How, then, is it possible to determine that an ice sheet in one hemisphere was really contemporary with an ice sheet or an ice age in the other ?
The attempt to maintain the assumption of the simultaneousness of glaciations for the older geological periods is unreasonable. I shall show in what follows that it cannot be established even for recent geological time. It is my impression that the material evidence for the assumption was never impressive, and that the assumption was never derived empirically from the evidence but was borrowed a priori from the parent assumption; that is, the assumption of the lowering of global temperatures during ice ages, an assumption which is, as already pointed out, in conflict with the laws of physics.
If it is true that the fundamental assumption underlying most of the theories produced to explain ice ages is in error, we should expect that these theories, despite their many differences, would have a common quality of futility, and so it turns out. It is interesting to list the kinds of hypothetical causes that have been suggested to explain ice ages on the assumption of a worldwide lowering of temperature. They are as follows :
a. Variations in the quantity of particle emission and of the radiant beat given off by the sun.
b. Interception of part of the sun’s radiation by clouds of interstellar gas or dust.
c. Variations in the heat of space; that is, the temperature of particles floating in space which, entering the earth’s atmosphere, might affect its temperature.
d. Variations in the quantities of dust particles in the atmosphere. from volcanic eruptions or other causes, or variations in the proportion of carbon dioxide in the atmosphere.
There are serious objections to all these suggestions. So far as the variation of the sun’s radiation is concerned, it is known that it varies slightly over short periods, but there is no evidence that it has ever varied enough, or for a long enough time, to cause an ice age. Evidence for the second and third suggestions is entirely lacking. The fourth suggestion is deprived of value because, on the one hand, no causes can be suggested for long-term changes in the number of eruptions or in the atmospheric proportion of carbon dioxide, and, on the other, there is insufficient evidence to show that the changes ever occurred.
I should make one reservation with regard to the fourth suggestion. There is at least one event that would provide an adequate cause for an increase in the atmosphere of both volcanic dust and carbon dioxide, and that is a displacement of the crust. The extremely far-reaching consequences of a displacement of the crust with respect to atmospheric conditions, and the importance of the atmospheric effects of a displacement for other questions, will be discussed in Chapter IX.
The theories listed above were attacked by Coleman, who complained that they were entirely intangible and unprovable. He said :
Such vague and accidental causes for climatic change should he appealed to only as a last resort unless positive proof some time becomes available showing that an event of the kind actually took place (87:282).
Another group of theories attempts to explain ice ages as the results of changes in the relative positions of the earth and the sun. These are of two kinds: changes in the distance between the earth and the sun at particular times because of changes in the shape of the earth’s orbit, and changes in the angle of inclination of the earth’s axis, which occur regularly as the result of precession. The argument that precession was the cause of ice ages was advanced by Drayson in the last century (117). The argument based on these astronomical changes has been brought up to date in the recent work of Brouwer and Van Woerkom (375:147-58) and Emiliani (132). It now seems that these astronomical changes may produce cyclical changes in the distribution of the sun’s heat, and perhaps in the amount of the sun’s heat retained by the earth, but it is agreed, by Emiliani and others, that by itself the insolation curve or net temperature difference would not be sufficient to cause an ice age without the operation of other factors, and so Emiliani suggests that perhaps changes in elevation coinciding with the cool phases of the insolation curve may have caused the Pleistocene ice ages. One weakness of this suggestion is, of course, the necessity to suppose the accidental combination of two independent causes for ice ages.
There is another objection to be advanced against all theories supposing a general fall of world temperatures during the ice ages. We have seen that ice ages existed in the tropics and that great ice caps covered vast areas on and near the equator. This happened not once but several times. The question is, if the temperature of the whole earth fell enough to permit ice sheets a mile thick to develop on the equator, just where did the fauna and flora go for refuge ? How did they survive ? How did the reef corals, which require a minimum seawater temperature of 68° F. throughout the year, manage to survive ? We know that the reef corals, for example, existed long before the period of the tropical ice sheets. Furthermore we know that the great forests of the Carboniferous Period, which gave us most of our coal, lived both earlier than and contemporarily with the glaciations of Africa and India, though in different places. Obviously this would have been impossible if the temperature of the whole earth had been simultaneously reduced, for the equatorial zone itself would have been uninhabitable, while all other areas were still colder. It is small wonder that W.B. Wright insisted, over a quarter of a century ago, that the Permo-Carboniferous ice sheets in Africa and India were proof of a shift of the poles (450).
4. The New Evidence of Radiocarbon Dating
The question of the causes of ice ages has been given increased importance by a recent revolution in our methods of dating geological events. In the course of the last twenty years all of our ideas regarding the chronology of the recent ice ages, their durations, and the speed of growth and disappearance of the great ice sheets have been transformed. This is altogether the most important new development in the sciences of the earth. The repercussions in many directions are most remarkable.
In order to get an idea of the extent of the change, let us see what the situation was only ten or fifteen years ago. As everybody is aware, geologists are used to thinking in terms of millions of years. To a geologist a period of 1,000,000 years has come to mean almost nothing at all. He is actually used to thinking that events that took place somewhere within the same 20,000,000-year period were roughly contemporaneous. As to the ice ages, the older ones were simply thrown into one of these long geological periods, but there was no way to determine their durations (except very roughly), their speeds of development, or precisely when they happened. It was convenient to assume that they had endured for hundreds of thousands or for millions of years, though no real evidence of this existed.
So far as the most recent division of geologic time, the Pleistocene, was concerned, geologists, with much more evidence to work from, saw that there had been at least four ice ages in a period of about 1,000,000 years. They consequently proposed the idea that the Pleistocene was not at all like previous periods. It was exceptional because it had so many ice ages. They may have been misled by failure to take sufficient account of the fact that glacial evidence is very easily destroyed, and that, as we go further back into geological history, the mathematical chances of finding evidences of glaciation, never very good, decrease by geometical progression.
Down to twenty years ago it was the considered judgment of geologists that the last ice age in North America, which they refer to as the Wisconsin glaciation, began about 150,000 years ago and ended about 30,000 years ago, as I have already said.
This opinion appeared to be based upon strong evidence. The estimates of the date of the end of the ice age were supported by the careful counting of clay varves (6) and by numerous seemingly reliable estimates of the age of Niagara Falls. As a consequence, experts were contemptuous of all those who, for one reason or another, attempted to argue that the ice age was more recent. One of these was Drayson, whose theory called for a v cry recent ice age (117). His followers produced much evidence, but it was ignored. When the Swedish scientist Gerard de Geer established by clay-varve counting that the ice sheet was withdrawing from Sweden as recently as 13,000 years ago, the implications were not really accepted, nor were his results popularly known. Books continued to appear, even thirty years afterward, with the original estimates of the age of the ice cap.
Then, following World War II, nuclear physics made possible the development of new techniques for dating geological events. One of these was radiocarbon dating.
The method of radiocarbon dating was developed by Willard F. Libby, nuclear physicist of the University of Chicago. It uses an isotope of carbon (Carbon 14) which has a “half-life” of about 5,570 years. A half-life is the period during which a radioactive substance loses half its mass by radiation. Among the very numerous artificial radioactive elements created in nuclear explosions some have halflives of millionths of seconds; others, occurring in nature, have half-lives of millions of years. For geological dating it is necessary to have radioactive elements that diminish significantly during the periods that have to be studied, and that occur in nature.
Since radiocarbon exists in nature and has a relatively short halflife, the quantity of it in any substance containing organic carbon will decline perceptibly in periods of a few centuries. By estimating how much carbon was contained originally in the specimen and then measuring what still remains, the date of its geologic formation can be found to within a small margin of error.
When this method was first developed by Libby, it could date anything containing carbon of organic origin back to about 20,000 years ago. Since then the method has been improved, through the efforts of many scientists, and its range has been approximately tripled.
The first major result of the radiocarbon method was the revelation that the last North American ice sheet had indeed disappeared at a very recent date. Tests made in 1951 showed that it staged a readvance in Wisconsin as recently as 11,000 years ago (272:105). When this date is compared with other dates showing the establishment of a climate like the present one in North America, it seems that most of the retreat and disappearance of the great continental ice cap, at least in the United States, can have taken little more than two or three thousand years. We shall examine these dates in detail in Chapter IV.
What was the significance of this new discovery, besides showing how wrong the geologists had been before ? The fact is that so sudden a disappearance of a continental ice cap raises fundamental questions. It contradicts some basic assumptions of geological science. What has become of those gradually acting forces that were supposed to govern glaciation as well as all other geological processes ? What factor can account for this astonishing rate of change ? It seems selfevident that no astronomical change and no subcrustal change deep in the earth can occur at that rate.
When this discovery was made, I expected that the next revelation must be to the effect that the Wisconsin ice sheet had had its origin at a much more recent time than was suspected, and that the whole length of the glacial period was but a fraction of the former estimates. I had a while to wait, because radiocarbon dating in 1951 was not able to answer the question. By 1954, however, the technique had been improved so that it could determine dates as far back as 30,000 years ago. Many datings of the earlier phases of the Wisconsin glaciation were made, and Horberg, who assembled them, reached the conclusion that the ice cap, instead of being 150,000 years old, had appeared in Ohio only 25,000 years ago (222:278-86). This conclusion has been so great a shock that some writers have sought to evade the clear implications by questioning the reliability of the radiocarbon method. Horberg betrays evidence of the intensity of the shock to accepted beliefs when he says that the results of the evidence are so appalling from the standpoint of accepted theory that it may be necessary either to abandon the concept of gradual change in geology or to question the radiocarbon method.
In this book I am not going to question the general reliability of the radiocarbon method. I intend merely to question the theories with which the new evidence is in conflict. Doctor Horberg says that the necessity to compress all the later stages of the Wisconsin glaciation into the incredibly short period of 15,000 or 20,000 years involves an acceleration of geological processes—snowfall, rainfall, erosion, sedimentation, and melting—that seems to challenge the principle laid down by the founder of modern geology, Sir Charles Lyell, over a century ago. Lyell’s principle, called “uniformitarianism,” stated that geological processes have always gone on about as they are going on now.
The Wisconsin ice cap went through a number of oscillations, warm periods of ice recession alternating with cold periods of ice readvance. Horberg is at a loss to see what could cause them to occur at the velocity required by the radiocarbon dates. These seem to require an annual movement of the ice front of 2,005 feet, “two to nine times greater than the rate indicated by varves and annual moraines” (222:283).[1]
The fact that these new data call into question some basic ideas in geology is recognized by Horberg :
Probably only time and the progress of future studies can tell whether we cling too tenaciously to the uniformitarian principle in our unwillingness to accept fully the rapid glacier fluctuations evidenced by radiocarbon dating (222:285).
Recent geological literature shows that a rather desperate effort is being made to blur the significance of the new data. However, I would like to suggest some far-reaching implications. We have seen an ice sheet appear and disappear in—geologically speaking—a twinkling of an eye. There are three deductions to be made :
a. Any theory of ice ages must give a cause that can operate that fast.
b. If the last ice cap in North America appeared and disappeared in a short time, we cannot assume that the ancient ice caps lasted for longer periods.
c. If other geological processes are correlated with ice ages, then their tempo must also have been faster than we have supposed, and a cause must be found for their accelerated tempo.
It is clear that none of the great glaciations of the past can be explained by the theories hitherto advanced. The only ice age that is adequately explained is the present ice age in Antarctica. This is excellently explained. It exists, quite obviously, because Antarctica is at the pole, and for no other reason. No variation of the sun’s heat, no galactic dust, no volcanism, no subcrustal currents, and no arrangements of land elevations or sea currents account for the fact. We may conclude that the best theory to account for an ice age is that the area concerned was at a pole. We thus account for the Indian and African ice sheets, though the areas once occupied by them are now in the tropics. We account for all ice sheets of continental size in the same way.
Stokes has provided an excellent list of specifications for a satisfactory ice-age theory, every one of which is met by the assumption of crust displacements as the fundamental cause (395:815-16):
a. An initiating event or condition.
b. A mechanism for cyclic repetitions or oscillations within the general period of glaciation.
c. A terminating condition or event.
d. It should not rely upon unprovable, unobservable, or unpredictable conditions when well-known or more simple ones will suffice.
e. It must solve the problem of increased precipitation with colder climate.
f. The facts call for a mechanism that either increases the precipitation or lowers the temperature very gradually over a period of thousands of years.
It is evident that a displacement of the crust could initiate an ice age by moving a certain region into a polar zone, while a later displacement could end the ice age by moving the same area away from the polar zone. The increased precipitation and the oscillations of the borders of the ice sheets can be explained by the atmospheric effects that would result from volcanism associated with the movement of the crust. These effects will be discussed in later chapters.
THE FAILURE TO EXPLAIN CLIMATIC CHANGE
IN THE last chapter it was suggested that the ice ages can be explained by the assumption of frequent displacements of the earth’s crust but that they cannot, at least for recent time (the Pleistocene Epoch) be explained by continental drift. The ice ages, however, represent only one side of the problem. If they are instances of extremely cold climates distributed in an unexplained manner on the earth’s surface, there were also warm climates whose distribution is equally unexplained.
In connection with these warm climates in the present polar regions, there arises a contradiction of an especially glaring character. On the one hand there is evidence that the distribution of plants and animals in the past did not, as a rule, follow the present arrangements of the climatic zones. On the other hand, the trend of the new evidence is to show that climatic zones have always been about as clearly distinguished by temperature differences as they are today. This is in flat contradiction to the assumption, still widely held, that the earth, during most of geological history, did not possess clearly demarcated climatic zones. We are forced to conclude that, since many ancient plants and animals were not distributed according to the present climatic zones, the zones themselves have changed position on the earth’s surface. This requires, as we have seen, that the surface shall have changed position relative to the axis of rotation. We shall now examine the evidence that supports this view.
There have been many times during the history of the globe when the continent of Antarctica, now covered by a polar ice cap as much as two miles thick and covering an area of nearly 6,000,000 square miles, had warm climates.
So far as we know at present, the very first evidence of an ice age in Antarctica comes from the Eocene Epoch (52:244). This was barely 60,000,000 years ago. Before that, for some billion and a half years, there is no suggestion of polar conditions, though very many earlier ice ages existed in other parts of the earth. Henry, in The White Continent, cites evidence of the passing of long temperate ages in Antarctica. He describes the Edsel Ford Mountains, discovered by Admiral Byrd in 1929. These mountains are of nonvolcanic, folded sedimentary rocks, the layers adding up to 15,000 feet in thickness. Henry suggests that they indicate long periods of temperate climate in Antarctica :
The greater part of the erosion probably took place when Antarctica was essentially free of ice, since the structure of the rocks indicates strongly that the original sediment from which they were formed was carried by water. Such an accumulation calls for an immensely long period of tepid peace in the life of the rampaging planet (206:113).
Most sedimentary rocks are laid down in the sea, formed of sediment brought down by rivers from nearby lands. The lands from which the Antarctic sediments were brought seem to have disappeared without a trace, but of the sea that once existed where there is now land we have plenty of evidence. Brooks remarks :
... In the Cambrian we have evidence of a moderately warm sea stretching nearly or right across Antarctica, in the form of thick limestones very rich in reef-building Archaeocyathidae (52:245).
Millions of years later, when these marine formations had appeared above the sea, warm climates brought forth a luxuriant vegetation in Antarctica. Thus, Sir Ernest Shackleton is said to have found coal beds within 200 miles of the South Pole (71:80), and later, during the Byrd expedition of 1935, geologists made a rich discovery of fossils on the sides of lofty Mount Weaver, in Latitude 86° 58' S., about the same distance from the pole, and two miles above sea level. These included leaf and stem impressions and fossilized wood. In 1952 Dr. Lyman H. Dougherty, of the Camegie Institution of Washington, completing a study of these fossils, identified two species of a tree fern called Glossopteris, once common to the other southern continents (Africa, South America, Australia), and a giant tree fern of another species. In addition, he identified a fossil footprint as that of a mammallike reptile. Henry suggests that this may mean that Antarctica, during its period of intensive vegetation, was one of the most advanced lands of the world as to its life forms (207).
Soviet scientists have reported finding evidences of a tropical flora in Graham Land, another part of Antarctica, dating from the early Tertiary Period (perhaps from the Paleocene or Eocene) (364:13).
It is, then, little wonder that Priestly, in his account of his expedition to Antarctica, should have concluded :
... There can be no doubt from what this expedition and other expeditions have found that several times at least during past ages the Antarctic has possessed a climate much more genial than that of England at the present day ... (349d:210)
Further evidence is provided by the discovery by British geologists of great fossil forests in Antarctica, of the same type that grew on the Pacific coast of the United States 20,000,000 years ago (206:9). This, of course, shows that after the earliest known Antarctic glaciation in the Eocene, the continent did not remain glacial but had later episodes of warm climate.
Umbgrove adds the observation that in the Jurassic Period the floras of Antarctica, England, North America, and India had many plants in common (420:263).[2]
There is one group of theories for explaining these facts to which we cannot appeal because of their inherent and obvious weaknesses. These are the theories that try to explain warm and cold periods in Antarctica by changes in land elevations, changes in the directions of ocean currents, changes in the intensity of solar radiation, and the like. It is obvious, for instance, that no hypothetical warm currents could make possible the existence of warm climates in the center of the great Antarctic continent if that continent were at the pole, and if by some miracle Antarctica did become warm, how could forests possibly have flourished there deprived of sunlight for half the year ?
The Arctic regions have been more accessible, and consequently they have been more thoroughly explored, than the Antarctic. It was from them that the first evidence came of warm-climate floras in a polar region. Most of the theories developed by those defending the theory of the permanence of the poles were specially designed to explain these facts.
One method of explaining the evidence was to suggest that the plants and animals of past geological areas, even though they belonged to similar genera or families as living plants and animals, and closely resembled them in structure, may have been adapted to very different climates. This argument often had effect, for no one could exclude the possibility that, in a long geological period, species might make successful adjustments to different climatic conditions. Where single plants were involved such a possibility could not be dismissed. Where, however, whole groups of species, whole floras and faunas, were involved, there was increased improbability that they could all have been adjusted at any one time to a radically different environment from that in which their descendants live today. For this reason, and because the structure of plants has a definite relationship to conditions of sunlight, heat and moisture, biologists have abandoned this method of explaining the facts. Barghoorn, for example, says that fossil plants are reliable indicators of past climate (375:237-38).
It may be worthwhile to review, very briefly, some high points of the climatic history of the Arctic and sub-Arctic regions, beginning with one of the oldest periods, the Devonian, and coming down by degrees to periods nearer our own. (During this discussion the reader may find it helpful to refer to the table of geological periods, page 2.)
The Devonian evidence is particularly rich and includes both fauna and flora. Doctor Colbert, of the American Museum of Natural History, has pointed out that the first known amphibians have been found in this period in eastern Greenland, near the Arctic Circle, though they must have required a warm climate (375:256). Many species of reef corals, which at present require an all-year seawater temperature of not less than 68° F. (102:108), have been found in Ellesmere Island, far to the north of the Arctic Circle (389:2). Devonian tree ferns have been found from southern Russia to Bear Island, in the Arctic Ocean (177:360). According to Barghoorn, assemblages of Devonian plants have been found in the Falkland Islands, where a cold climate now prevails, in Spitzbergen, and in Ellesmere Island, as well as in Asia and America (375:240). In view of this, he remarks :
The known distribution of Devonian plants, especially their diversification in high latitudes, suggests that glacial conditions did not exist at the poles (375:240).
In the following period, the Carboniferous, we have evidence summed up by Alfred Russel Wallace, co-author with Darwin of the theory of evolution :
In the Carboniferous formation we again meet with plant remains and beds of true coal in the Arctic regions. Lepidodendrons and calamites, together with large spreading ferns, are found at Spitzbergen, and at Bear Island in the extreme north of Eastern Siberia; while marine deposits of the same age contain an abundance of large stony corals (435:202).
In the Permian, following the Carboniferous, Colbert reports a find of fossil reptiles in what is now a bitterly cold region : “Large Permian reptiles ... are found along the Dvina River of Russia, just below the Arctic Circle, at a North Latitude of 65°" (375:259). Colbert explains that these reptiles must have required a warm climate. In summing up the problem of plant life for the many long ages of the Paleozoic Era, from the Devonian through the Permian, Barghoorn says that it is “one of the great enigmas” of science (375:243).
Coming now to the Mesozoic Era (comprising the Triassic, Jurassic and Cretaceous Periods), Colbert reports that in the Triassic some amphibians (the labyrinthodonts) ranged all the way from 40° S. Lat. to 80° N. Lat. About this time the warm-water Ichthyosaurus lived at Spitzbergen (375:262-64). For the Jurassic, Wallace reports :
In the Jurassic Period, for example, we have proofs of a mild arctic climate, in the abundant plant remains of East Siberia and Amurland. ... But even more remarkable are the marine remains found in many places in high northern latitudes, among which we may especially mention the numerous ammonites and the vertebrae of huge reptiles of the genera Ichthyosaurus and Teleosaurus found in Jurassic deposits of the Parry Islands in 77° N. Lat. (435:202).
For the Cretaceous Period, A.C. Seward reported in 1932 that “the commonest Cretaceous ferns [of Greenland] are closely allied to species ... in the southern tropics” (373:363-71). Gutenberg remarks : “Thus, certain regions, such as Iceland or Antarctica, which are very cold now, for the late Paleozoic or the Mesozoic era show clear indications of what we would call subtropical climate today, but no trace of glaciation; at the same time other regions were at least temporarily glaciated” (194:195). This evidence, linked in this way with the problem of the ice ages we have already discussed, reveals the existence of a single problem. Ice ages in low latitudes, and warm ages near the poles, are, so to speak, the sides of a single coin. The correct explanation of one will probably involve the explanation of the other.
Following the Cretaceous, the Tertiary Period shows the same failure of the fauna and flora to observe our present climatic zones. Scott, for example, says : “The very rich floras from the Green River shales, from the Wilcox of the Gulf Coast and from the Eocene of Greenland show that the climate was warmer than in the Paleocene, and much warmer than today” (372:103).
In this Eocene Epoch we find evidence of warm climate in the north that is truly overwhelming. Captain Nares, one of the earlier explorers of the Arctic, described a twenty-five-foot seam of coal that he had thought was comparable in quality to the best Welsh coal, containing fossils similar to the Miocene fossils of Spitzbergen. He saw it near Watercourse Bay, in northern Greenland (319:II, 141-42). Closer examination revealed that it was, in reality, lignite. Nevertheless, the contained fossils clearly indicated a climate completely different from the present climate of northern Greenland :
The Grinnell Land lignite indicates a thick peat moss, with probably a small lake, with water lilies on the surface of the water, and reeds on the edges, and birches and poplars, and taxodias, on the banks, with pines, firs, spruce, elms and hazel bushes on the neighboring hills ... (319:II, 335).
Brooks thinks that the formation of peat bogs requires a rainfall of at least forty inches a year and a mean temperature above 32° F. (52:173). This suggests a very sharp contrast with present Arctic conditions in Grinnell Land.
DeRance and Feilden, who did the paleontological work for Captain Nares, also mention a Miocene tree, the swamp cypress, that flourished from central Italy to 82° N. Lat., that is, to within five hundred miles of the pole (319:II, 335). They show that the Miocene floras of Grinnell Land, Greenland, and Spitzbergen all required temperate climatic conditions with plentiful moisture. They mention especially the water lilies of Spitzbergen, which would have required flowing water for the greater part of the year (319:II, 336).
In connection with the flora of Spitzbergen and the fauna mentioned earlier, it should be realized that the island is in polar darkness for half the year. It lies on the Arctic Circle, as far north of Labrador as Labrador is north of Bermuda.
Wallace describes the flora of the Miocene. He points out that in Asia and in North America this flora was composed of species that apparently required a climate similar to that of our southern states, yet it is also found in Greenland at 70° N. Lat., where it contained many of the same trees that were then growing in Europe. He adds :
But even farther North, in Spitzbergen, 78° and 79° N. Lat. and one of the most barren and inhospitable regions on the globe, an almost equally rich fossil flora has been discovered, including several of the Greenland species, and others peculiar, but mostly of the same genera. There seem to be no evergreens here except coniferae, one of which is identical with the swamp-cypress (Taxodium distichum) now found living in the Southern United States. There are also eleven pines, two Libocedrus, two Sequoias, with oaks, poplars, birches, planes, limes, a hazel, an ash, and a walnut; also water lilies, pond weeds, and an Irisaltogether about a hundred species of flowering plants. Even in Grinnell Land, within 8¼ degrees of the pole, a similar flora existed . (446:182-84).
It has been necessary to dwell at length on the evidence of the warm polar climates, because this is important for the discussion that follows.
The evidence I base presented above (and a great deal more, omitted for reasons of space) has long created a dilemma for geology. Only two practical solutions have offered themselves.[3] One is to shift the crust, and the other is to suggest that climatic zones like the present ones have not always existed. It is often suggested that the climates have been very mild, virtually from pole to pole, at certain times. The extent to which the latter theory is still supported is eloquent evidence of the theory of the permanence of the poles. When one inquires as to the evidence for the existence of such warm, moist climates, a peculiar situation is revealed. There is no evidence except the fossil evidence that the theory is supposed to explain. Could there be a better example of reasoning in a circle ? Colbert cites evidence that the Devonian animals were spread all over the world, and then remarks that therefore “... it is reasonable to assume ... that the Devonian Period was a time of widely spread equable climates, a period of uniformity over much of the earth’s surface” (375:255). According to him, the same situation held true through the Paleozoic and Mesozoic and even much later periods (375:268). Other paleontologists reasoned in the same way. Goldring, for example, remarked : “The Carboniferous plants had a worldwide distribution, suggesting rather uniform climatic conditions” (177:362). She drew the same conclusions from the worldwide distribution of Jurassic flora (177:363).
Is this theory of universal temperate climates inherently reasonable ? The answer is that it is not. It involves, in the first place, ignoring the astronomical relations of the earth and the sun. The theory requires us to assume the existence of some factor powerful enough to negate the variation of the sun’s heat with latitude which, of course, is due to the angle of inclination of the earth’s axis of rotation. As Professor George W. Bain, of Amherst, has pointed out, the result of this is that
... The thermal energy arriving at the earth’s surface per day per square centimeter averages 430 gram calories at the equator but declines to 292 gram calories at the 40th parallel and to 87 gram calories at the 80th parallel ... (18:16).
What force sufficiently powerful to counteract that fact of astronomy can be suggested, and, more important, supported by convincing evidence ?
It was thought at first that universal temperate climates might be accounted for by the theory of the cooling of the earth. Those who favored this theory (253, 292) argued that since, in earlier ages, the earth was hotter, the ocean water then evaporated much more rapidly, and it formed thick clouds that reflected the sun’s radiant energy back into space. The cloud blanket shut out the sun’s radiation but kept in the heat that radiated from the earth itself, and this acted to distribute the heat evenly over the globe. The cloud blanket must have been thick enough to make the earth a dark, dank, and dismal place. Since, as Colbert shows, fossils are found outside the present zones appropriate to them even in recent geological periods, such conditions must have obtained during about 90 percent of the earth’s whole history, and most of the evolution of living forms must have taken place in them.
For a number of reasons, including the difficulty of explaining how plants can have evolved in the polar regions without sunlight, this theory has been abandoned. We have also seen that the idea that the earth was ever hotter than now has recently been undermined. This has destroyed the dependability of the theory’s basic assumption.
The fact that the theory never was reasonable is shown from Coleman’s arguments against it, advanced more than a quarter of a century ago. He pointed out that not only are ice ages known from the earliest periods (from the Precambrian) but there is evidence that some of these very ancient ice ages were even more intensely cold than the recent ice age that came to an end 10,000 years ago (87:78), No less than six ice ages are known from the Precambrian (420:260). The evidence of one of these Precambrian or Lower Cambrian ice ages is interestingly described by Brewster :
In China, in the latitude of northern Florida, there is a hundred and seventy feet of obvious glacial till, scratched boulders and all, and over it lie sea-floor muds containing lower Cambrian trilobites, the whole now altered to hard rock (45:204).
It is obvious that such ice ages (and evidences of more of them are frequently coming to light) are in conflict with the theory of universal equable climates. Some of them are found right in the midst of periods thought to have been especially warm, such as the Carboniferous.
Coleman presents other geological evidence against the theory. The fact that most of the fossils found arc those of warm-climate creatures is, he thinks, misleading. Plants and animals are more easily fossilized in warm, moist climates than they are in cold, arid ones. Fossilization, even under the most favorable conditions, is a rare accident. The fauna and flora of the temperate and arctic zones of the past were seldom preserved (87:252). Thus, while the finding of fossils of warm-climate organisms all over the earth is an argument against the permanence of the present arrangement of the climatic zones, it is not an argument for universal mild climates.
Another argument against such climates may be based upon the evidences of desert conditions in all geological periods. These imply worldwide variations in climate and humidity. Both Brooks (52:24-25, 172) and Umbgrove (420:265) stress the importance of this evidence. One of the most famous formations of Britain—the Old Red Sandstone—is apparently nothing but a fossil desert. Coleman points to innumerable varved deposits in many geological periods as evidence of seasonal changes (87:253), which, of course, imply the existence of climatic zones.
Ample evidence of the existence of strongly demarcated climatic zones through the earth’s whole history (at least since the beginning of the deposition of the sedimentary rocks) comes from other sources. Barghoorn cites the evidence of fragments of fossil woods from late Paleozoic deposits in the Southern Hemisphere that show pronounced ring growth, indicating seasons; he also points out that in the Permo-Carboniferous Period floras existed that were adapted to very cold climate (375:242). Colbert himself reports good evidence of seasons in the Cretaceous Period, in the form of fossils of deciduous trees (375:265).
Umbgrove cites the geologist Berry, who states that the fossilized woods from six geological periods, from the Devonian to the Eocene, show well-marked annual rings, indicating seasons like those of the present time. Furthermore, Berry goes on to say :
Detailed comparisons of these Arctic floras with contemporary floras from lower latitudes ... show unmistakable evidence for the existence of climatic zones ... (420:266).
Brooks concludes, on the basis of Berry’s evidence, that climatic zones existed in the Eocene (52:24). Ralph W. Chancy, after a study of the fossil floras of the Tertiary Period (from the Eocene to the Pliocene), concluded that climatic zones existed (72:475) during that whole period. The distinguished meteorologist W.J. Humphreys, whose fundamental work, The Physics of the Air, remains a classic, remarked in 1920 that there was no good evidence of the absence of climatic zones at any time from the beginning of the geological record. Finally Dr. C.C. Nikiforoff, an expert on soils (both contemporary and fossil soils), has stated that “in all geological times there were cold and warm, humid and dry climates, and their extremes presumably did not change much throughout geological history” (375:191). We will return, below, to the significance of fossil soils and present other evidence showing persistence of sharply demarcated climatic zones during the earth’s whole history. But where, at this point, does the evidence leave us ?
On the one hand, the evidence shows that the plants and animals of the past were distributed without regard to the present direction of the climatic zones. I have been unable to do more than suggest the immensity of the body of evidence supporting this conclusion. On the other hand, the attempt to deny the existence, in the past, of sharply demarcated climatic zones like those of the present has failed. It may even be said to have failed sensationally. There is no scrap of evidence for it except the evidence it is supposed to explain, while, on the other hand, it is in contradiction with both the fundamentals of astronomy and the preponderance of the geological facts.
So we are left with a clear-cut conclusion: Climatic zones have always existed, but they have followed different paths on the face of the earth. If changes in the position of the axis of rotation of the earth, and of the earth upon its axis, are equally impossible, and if the theory of continental drift provides no satisfactory solution for reasons already discussed (Chapter I), then we are forced to the conclusion that the surface of the earth must often have been shifted over the underlying layers.
Another suggestion for displacements of the earth’s crust, to which I have already referred, is that of Karl A. Pauly, who has contributed new lines of evidence in support of such shifts. He has based his theory on Eddington’s suggestion that the earth’s crust may have been gradually shifted through time by the effects of tidal friction. The evidence for displacements presented by Pauly is most impressive.
Pauly finds, from a study of the elevations above sea level of the terminal moraines of mountain glaciers in all latitudes, that there is a correlation of elevation with latitude. While it is true that many factors influence the distance a mountain glacier may extend downward toward sea level, latitude is one of them, and by using a sufficient number of cases it is possible to average out the other factors and arrive at the average elevation of mountain glacier moraines above sea level for each few degrees of latitude from the equator toward the poles. This gives us a curve that makes it possible to compare the elevations of the terminal moraines of mountain glaciers that existed during the Pleistocene Epoch. Pauly finds that these moraines do not agree with the curve, indicating unmistakably a displacement of the earth’s crust (342:89).
Pauly cites another impressive line of evidence in support of displacements of the lithosphere. He has compared the locations of the coal deposits of several geological periods (many of which are now in polar regions) with the locations of ice caps for the same periods. He lists 34 coal deposits regarded as of Jurassic-Liassic age and 17 of Triassic-Thaetic age, and finds that, if it is assumed that the centers of the ice caps of that time were located at the poles, then these coal deposits would have been located within or just outside the tropics, as would be correct. He says :
The very definite location of these coal deposits within the Trias-Jura tropical and subtropical zones cannot be mere coincidence. The distribution indicates the lithosphere has shifted (342:96).
Of the Permo-Carboniferous coal deposits, very widely distributed over the earth, he says that “95 out of 105 listed in The Coal Resources of the World lie within or just outside of the tropics as determined by the assumption that the North or South Pole lay under the center of one of the Permo-Carboniferous ice sheets” (342:97).
Professor Bain has gone considerably beyond the categories of evidence that we have so far discussed. He has considered the specific chemical processes controlled by sunlight and varying according to latitude, and the remanent chemicals typical of soils developed in the different climatic zones. He has extended this sort of analysis also to marine sediments.
Bain’s approach to the problem has many advantages. It circumvents, for one thing, the argument that plants of the past may have been adjusted to climates different from those in which their modern descendants live. He begins with a precise definition of each climatic zone in terms of the quantities of the sun’s heat reaching the earth’s surface. He points out that, as is known, the seasonal variation of this heat increases with distance from the equator (18:16). He then describes the global wind pattern resulting from this distribution of the sun’s energy, defining clearly the conditions of the horse latitudes, in which most of the earth’s deserts are found, and the meteorology of the polar fronts. He shows that there are distinct and different complete chemical cycles in each of these areas, and corresponding cycles in the sea. Many of the chemical compounds produced in each of these areas are included, naturally, in the rocks formed from the sediments, and they remain as permanent climatic records.
It is impossible, because of limitations of space, to do justice to Bain’s comprehensive approach to this question. He establishes that great differences exist between the mineral components of the rocks in different climatic zones, resulting from the difference in the amount of the sun’s radiant heat. With regard to the polar soils, he found that they are developed in circles on the earth’s surface rather than in bands. Temperate and tropical soils are, of course, found in bands, since the zones are bands that encircle the earth.
It is clear that Bain has established a sound method for the study of the climates of the past. He has applied his method to the study of the climates of five periods, the Cambrian, Ordovician, Silurian, Devonian, and Permian (19a) (Figs. 11, 12, 13, 14, and 15, pp. 74-78), with significant results. He concludes, first, that climatic zones, representing the different distributions of solar heat, existed in those periods just as at present. This is proved by the specific remanent chemicals included in these rocks, which differ exactly as do the sediments of the different zones at the present time. This is, of course, fatal for the theory of universal equable climates.
His second conclusion is that the directions of the climatic zones have changed enormously in the course of time. He finds the equator running through the New Siberian Islands (in the Arctic Ocean) in the Permo-Carboniferous Period, and North and South America lying tandem along it (18:17). The evidence he uses seems to establish his essential point (and ours) that the climatic zones themselves have shifted their positions on the face of the earth.
Bain has drawn some interesting further conclusions. He states that the earth’s crust must have been displaced over the interior layers and that “fixity of the axis of the earth relative to the elastice outer shell just is not valid. ...” (18:46). He points to the fossil evidence of the cold zones (distributed in circular areas) and says, “... The recurrent change in position of these rings through geologic time can be accounted for now only on the basis of change in the position of the elastic shell of the earth relative to its axis of rotation” (18:46).
Even without the evidence of geomagnetism, or even if that evidence should someday be discredited, the evidence produced by Bain would be sufficient to establish the truth of displacements of the lithosphere. However, the mechanism he suggests does not seem satisfactory. He depends upon the effects of erosion. He points out that at the present time the balance of the sediment transfer by rivers is toward the equator. The mass thus added to the lithosphere on the equator has been given increased velocity by the fact of being moved equatorward, and this would tend to accelerate the rotation, but the gyroscopic effect of this, he thinks, would be to cause the rotating globe to precess in a direction at 90° to the direction of the rotation. The crust alone, however, not the entire globe, would be shifted (19a:128-129).
There seem to me to be three objections to this mechanism. In the first place, it seems probable that isostatic adjustment of the lithosphere to the transfer of sediments would eliminate the effect. A poleward flow of material under the lithosphere would roughly equal the equatorward movement of sediment. A second objection is that there is no reason to suppose that with every position of the lithosphere the balance of sediment transfer would be toward the equator. This would require changes in the drainage systems of all the continents with each shift of the crust. The third objection is that the geomagnetic evidence suggests polar shifts were far more frequent than indicated by Bain. Bain makes no use of the continental-drift hypothesis.
Bain has pointed out (18) that among other indications of latitude, sea crustaceans and corals may indicate latitude either by the presence or absence of evidence of seasonal variations in growth. It happens that corals have been very thoroughly investigated from precisely this point of view.
By a remarkable parallelism of development, another theory of displacement of the earth’s crust took shape on the opposite side of the earth at about the same time that Mr. Campbell and I started on our project. Professor Ting Ying H. Ma, an oceanographer, then at the University of Fukien, China, came to the conclusion, after many years of study of fossil corals, that many total displacements of the earth’s lithosphere must have taken place. I did not become aware of Ma’s work until I was introduced to it by David B. Ericson, of the Lamont Geological Observatory, in 1954. Ericson has, in fact, taken a leading role in introducing Ma’s work to American scientists.
For about twenty years previous to the time I mention, Ma had intensively pursued the study of living and fossil reef corals. He very early noticed the special characteristic of reef corals referred to by Bain but hitherto ignored by writers on corals. He saw that, at distances from the equator, there were seasonal differences in the rates of coral growth and that the evidences of these were preserved in the coral skeleton. Specifically he observed that in winter the coral cells are smaller and denser; in summer they are larger and more porous. Together these two rings make up the growth for one year.
Studying living coral reefs in various parts of the Pacific, comparing, measuring, and tabulating coral specimens of innumerable species, making photographic studies of the coral skeletons, Ma established that the rates of total annual coral growth for identical or similar species within the range of the coralline seas increased with proximity to the equator, and that seasonal variation in growth rates increased with distance from the equator.
Other writers on corals have pointed out that there are numerous individual exceptions and irregularities in coral growth rates, deriving from the fact that the coral polyps feed upon floating food, which may vary in quantity from place to place, from day to day, and even from hour to hour (125:20-21; 298:52-53). Ma, however, has guarded himself against error by a quantitative and statistical approach. In several published volumes of coral studies (285-Z90) he has compiled tables running into hundreds of pages, and his studies have involved thousands of measurements.
When this indefatigable oceanographer had worked out the relations of coral growth with latitude, he possessed an effective tool with which to investigate the climates of the past. He studied specimens of fossil corals from many geological periods. He devoted separate volumes to the Ordovician, Silurian, Devonian, Cretaceous, and Tertiary Periods (285-289).
As Ma assembled the coral data for these periods, it became clear that the total width of the coralline seas had not varied noticeably from the beginning of the geological record. Not only was the existence of seasons in the oldest geological periods clearly indicated; it was also indicated that the average temperatures of the respective zones were about the same as at present.
The second result of Ma’s studies was to establish that the positions of the ancient coralline seas and, therefore, of the ancient equators were not the same as at present. They had evidently changed from one geological period to another. Ma first believed that this could be explained by the theory of drifting continents. Down to about 1949 he sought to fit all the evidence into that theory. By 1949, however, the accumulated evidence forced him to adopt a theory of total displacements of all the outer shells of the earth over the liquid core. By an instinct of conservatism, however, he did not abandon the theory of floating continents but combined it with the new theory.
Ma’s coralline seas ran in all directions (Figs. 16, 17, 18, 19, and 20, pp. 82-86); one of his equators actually bisected the Arctic Ocean. But he had great difficulty in matching up his equators on different continents. If, for example, he traced an equator across North America, he could not match it with an equator for the same period on the other side of the earth to make a complete circle of the earth. He therefore supposed that the continents themselves had been shifting independently and this had had the effect of throwing the ancient equators out of line. He therefore allowed, for each period, enough continental drift to bring the equators into line, and it seemed, when he did this, that in successive geological periods he did have increasing distances between the continents, as if the drift had been continuous.
Subsequently Ma developed his theory into a complete system, which is most interesting, and yet to which I think serious objections may be raised.
Corals are, according to Ma, excellent indicators of the climate for the time in which they grew, but by the nature of the case, since corals grow only in shallow water and grow upwards only as far as the surface, the period of time represented by a single fossil coral reef is of the order of a few thousand years only, as compared with the millions of years embraced by a geological period.
How short the continuous growth of a coral reef may be is indicated by numerous studies of the coral reefs of the Pacific. A.G. Mayor, for example, says :
... The modern reefs now constituting the atolls and harriers of the Pacific could readily have grown upward to sea-level from the floors of submerged platforms since the close of the last glacial epoch (298:52).
At Pago Pago harbor borings were made down to the basalt underlying the reef, and after estimates of the growth rate were arrived at, the age of the reef (Utelei) was estimated at 5,000 years. When these spans are compared with those of entire geological periods of the order of 20,000,000 or 30,000,000 years, it is clear how fragile must be any conclusions based on the assumption that a given coral reef in Europe was contemporary with another one in North America. It is quite impossible in the present state of our knowledge to decide that they were in fact contemporary.
This means that Ma’s corals for a period like the Devonian may be indications of different equators that existed at different times during that period of 40,000,000 years. Therefore it is obvious that thousands of coral specimens would he required to give any certainty as to the actual climatic history of an entire geological period.
Very possibly Ma could have avoided combining the two different theories—the slipping of the shell of the earth and the drifting of continents—if he had supposed a sufficiently frequent slipping of the crust. The frequency of the displacements suggested by the theory presented in this book, which would involve many different equators in a single geological period, might remove his difficulties. As it is, he has to face all the geophysical and geological objections to the drifting-continent theory as well as difficulties with his displacement theory.
Studies appear from time to time in which attempts are made to trace climatic changes in specified areas over periods of millions of years. In one of these, for example (72), the conclusion is reached that there was a gradual cooling of the climate during a great many million years of the Tertiary Period. It is true that no cause of such a progressive cooling can be pointed to; neither is there any explanation as to why the climatic change had to be so gradual. It is simply assumed that the climatic change had to be gradual and that the cause of the change had to be such as to explain gradual changes.
It is important to define the evidence on which these conclusions are based. In the example I am considering, the facts are as follows :
a. The period of time involved is of the order of 30,000,000 years.
b. Wherever reference is made to the specific strata of rock selected for analysis of the climatic evidence (consisting of included fossils), it is clear that the time required for the deposition of any particular layer was of the order of 10,000 years.
c. It follows that during 30,000,000 years it would have been possible to have about 3,000 different layers of sedimentary rock.
d. A vast majority of these layers cannot be sampled, either because they no longer exist, or because they do not contain fossils, or simply because of the amount of work involved.
e. As a result, only spot checking is possible. Perhaps a dozen strata out of 3,000 may be studied, and from these it must be obvious that no dependable climatic record can be established.
f. Even with the unsatisfactory spot checking so far attempted, reversals of climatic trends have been observed (72).
g. Climatic conditions indicated by a layer of sediments deposited during a brief period of time in one location cannot be assumed to indicate the direction of climatic change over a great region or over the whole earth. It seems quite as reasonable to suppose that climatic change in other regions at the same time could have been in a different direction. Furthermore it cannot be assumed that two sedimentary deposits in different areas are of the same age because they both indicate climatic change in the same direction.
It may be concluded that claims for gradual climatic changes in the same direction over long periods of time and over great areas are unsupported by convincing evidence. They are supported by no reasonable hypothesis. We are left free to conclude that climatic change may have taken place in relatively short periods of time, and possibly in opposite directions at the same time, as the consequence of displacements of the lithosphere.
EVIDENCE FOR THE NORTH POLE
IN HUDSON BAY
IN THE preceding chapters much evidence has been presented to support the assumption of the displacement of the earth’s outer shells over the inner body, displacements that may have occurred rather frequently during the history of the earth. It is now time to tie down this assumption with concrete evidence that such a displacement has occurred, not in the remote past of the planet’s history but in very recent time, and not once but at least three times in that recent epoch that we call the Pleistocene. I will ask the leader’s indulgence for my descending to details in the examination of the evidence. This is not the sort of thing that he who runs may read, but, although the evidence is detailed, it is not particularly technical. It is the sort of evidence that murder-trial lawyer Perry Mason might
1. Since he said this, earlier phases of the glaciation have been discovered (see Chapter IV), but this does not alter the fact that the new dates testify to an enormous acceleration of the glacial stages already known.
2. In The New York Times for December 6, 1969, Walter Sullivan reported comments by Drs. Laurence M. Gould and Grover Murray on a discovery of vertebrate fossils in the Alexandra Mountains only a few degrees from the South Pole. These fossils were those of reptiles resembling those of the Triassic Period on other continents. It is interesting that the evidence is interpreted as virtual proof of continental drift : that is, of the break-up of a supercontinent since the Triassic. However, such a conclusion is not justified. Only the dating of the rocks enclosing the fossils by some means of absolute dating could really establish the fact that the animals lived in the Triassic Period, rather than 50,000,000 years earlier or later. A number of shifts of the lithosphere, with successive alterations of geographical connections could have permitted the migration of the species without postulating continental drift.
3. Continental drift is not acceptable because of the time factor. It cannot solve the problems of recent periods, that is, the Tertiary Period and the Pleistocene Epoch.