07. One Ice Age, or Many? (part 1)

CHAPTER 7
One Ice Age, or Many?

Glacial geologists believe that ice ages occurred about once every 100,000 years. There is no agreement concerning the exact number of ice ages, but the usual estimate is in the neighborhood of 20, with complete deglaciations between them. Kennett (1982, p. 747) believes there may have been as many as 30 glacial episodes during the late Cenozoic, which includes the late Pliocene and the Pleistocene. In addition, several large oscillations, called stadials and interstadials, are presumed interspersed within each cycle. The Genesis Flood, on the other hand, was a unique event, and, consequently, the initial conditions for a post-Flood ice age occurred only once. The concept of multiple ice ages is directly contradictory to the model presented in this book. Is there actual evidence for just one ice age, as opposed to many? The purpose of this chapter is to investigate this question.

One could attempt to analyze all the detailed descriptions of glacial deposits on earth, but instead, let us examine the general, large-scale evidence that is more-or-less accepted by a majority of glacial geologists. Because of their attachment to the multiple glaciation hypothesis, they do not see the implication of this evidence. Glacial sediments, laid down by the ice sheets, are complicated and confused, on the local as well as the regional scale. Because of the many difficulties involved, it is probably impossible to sort out some of this data, in any model. This chapter will focus only on the continental glacial deposits, which are the direct physical evidence of glaciation. Multiple glaciation, in relation to ocean sediments, was briefly discussed in Chapter 1, under the topic of the astronomical theory of the ice age, and has been treated elsewhere (Oard, 1984 a, b, 1985). The continental glacial debris shows much fewer “glaciations” than the ocean sediments. Investigators are actively engaged in an effort to reconcile the two records. The continental deposits are difficult to interpret, and the data are automatically fitted into the multiple glaciation model. In this chapter, a brief history of the multiple glaciation concept, with special focus on the alpine model, which held sway over the interpretation of geological data for over half a century will be presented. A discussion of the large-scale evidence for one ice age, as contrasted with multiple glaciations and their intervening interglacials follows. We will examine the basis for postulating interglacial periods, with special emphasis on soil stratigraphy. The chapter will end with an alternate explanation for the data used to support interglacial periods.

Early Debate on the Number of Glaciations

Glaciation, as an explanation for the surface deposits in the Alps and northern Europe, did not become popular until after 1840. It was not until Louis Agassiz published his Studies on Glaciers, that opinion switched from the Genesis Flood to glaciation, as the cause of the “drift,” although a few men had previously held such a view (Imbrie and Imbrie, 1979, pp. 19-46). Unfortunately, there was a resultant erosion of belief that the Genesis Flood was a historic reality. The catastrophist idea of the Noachian debacle was finally laid to rest when Louis Agassiz showed that his glacial theory could explain erratics, striations, till, fluvioglacial features, and so on. Old ideas die hard, however, and catastrophist absurdities still appeared in the literature of the early 1900’s (as they do even today) (Baker, 1978, p. 1255).

Early glacial theorists believed in only one ice age, but slowly, opinion changed to multiple ice ages. The reasons for this change are many. Some of them are: 1) the glacial deposits are complex, 2) till layers, separated by non-glacial deposits, do occur, 3) the complex behavior of modern glaciers was not well known at that time, and 4) the uniformitarian principle was strictly held. The earliest suggestion that more than one ice age had developed came in 1847, when Edouard Collomb reported two layers of till in the Vosges Mountains of France. These layers were separated by stream deposits, and could easily be interpreted as a minor retreat and readvance of the glacial terminus (Imbrie and Imbrie, 1979, p. 56). So the first suggestion of multiple glaciation was a likely misinterpretation. But the concept of multiple glaciations caught on. Two ice ages were soon claimed for other glaciated areas, although most geologists, at that time, preferred one glaciation, with minor oscillations (Bowen, 1978, pp. 1, 2; Imbrie and Imbrie, 1979, p. 57). Due to the complexity of the glacial sediments, by the middle 1870s three or more glacial periods were being proposed: “In some places, only two tills were found, but in others it was possible to show that there had been at least six separate glacial ages, each followed by a warm interval” (Imbrie and Imbrie, 1979, p. 90). Due to the influence of the alpine model, four ice ages were finally agreed upon, in the early 20th century. The alpine model has a valuable lesson to teach us, so it will be discussed in a separate section. The astronomical theory of the ice ages, although poorly developed at the time, influenced scientists to accept multiple ice ages. Charlesworth (1957, p. 911) states: “The sceptics in all countries include those who accept elevation as the cause of glaciation..., just as believers in astronomical causes favour multiple glaciation.” The sceptics he is referring to are those who believed in one glaciation.

Charlesworth (1957, pp. 920-924) lists all the areas that provide evidence for anywhere from one-to-six glaciations. Despite the influence of the alpine model (which was strong at that time), he believed the evidence mainly supported only two glacial epochs:

Bearing in mind the conscious or unconscious influence of the Alpine classification and the tendency to confuse minor variations or retreat phases with oscillations of interglacial magnitude, definite evidence cannot at present be said to exist for more than one long interglacial epoch (Charlesworth, 1957, pp. 923, 924). In other words, he believed the glacial sediments supported only two glaciations, with minor oscillations at the margin, and that the alpine classification influenced Quaternary geologists to think in terms of more than two. Notice, also, that Charlesworth indicates that minor oscillations, at the margin, have been taken to represent complete ice ages. As of 1957, a few mainstream scientists still believed in one glaciation (Lougee and Lougee, 1976), although the number had been steadily dwindling. Charlesworth (1957, pp. 911-914) devotes four pages of his massive 1,700-page tome, to refuting these monoglacialists. His criticism is valid within the uniformitarian framework, but the problems he presents can also be solved by a relatively mild climate, during a single ice age.

Glacial Sediments Complex

Why is there so much debate on the number of glaciations (which still continues today)? The reason is because the glacial sediments are indeed complex, and many processes, other than ice, have shaped them. Bowen (1978, pp. 173-180) states that glacial deposition is more complex than previously thought, and has received much erroneous interpretation. Modern glaciers show a great variety of depositional sequences, with special complexity near the margins. For instance, glacial till is acted on by rivers and streams, and also by currents in proglacial lakes, and it can flow downslope as a debris flow.

Different till layers have overlapping characteristics, and there are rapid lateral changes in facies or sediment type (Eyles, 1983). Consequently, it is difficult to distinguish between different till layers that were supposedly deposited by separate ice ages. The “type section” approach has normally been employed to classify and correlate glacial sediments, as well as pre-Pleistocene sediments. In this method, a “classical,” or well-behaved vertical sequence is selected that represents a specific period of time, and is then given a name, such as the Kansan till. Several of these type sections are pieced together from different regions to form a supposed time series. Vertical sections, or well cores taken from the periphery of glaciation usually penetrate only one layer of till, which causes difficulty in correlating the sediments to the type section. But each local vertical profile is, nevertheless, “dated,” by matching to one or more of these type sections. The type-section approach is simplistic and subjective. Many glacial geologists are advocating that it be replaced by a three-dimensional, or depositional basin approach. Eyles (1983, p. 15) states: “Many studies show that applying generalized stratigraphic names, derived from a single or few ‘type-sites,’ obscures the real nature of regional and local sedimentary sequences.” By applying the depositional basin or land-system approach, multiple till layers have often been found to be the product of only one ice sheet, rather than several. A recent controversy shows how difficult glacial deposits are to interpret. A classical area for studying multiple glaciations is the Scarborough Bluffs, on the north shore of Lake Ontario. Previous geological work had divided the bluffs into various till sheets, attributed to several different glaciations. More recent investigators not only changed the boundaries of lithostratigraphic units on the bluffs, but also concluded that the sediments were deposited by one ice advance. Furthermore, the whole sequence was presumed to have been laid down in a proglacial lake below a floating ice sheet, not brought into place directly by an ice sheet (Eyles et al., 1983a; Eyles and Eyles, 1983; Karrow, 1984). It would seem that glacial geology is in real trouble, if experts have difficulty telling the difference between sediments laid down directly by a glacier, and sediments dropped into a lake by floating ice.

Kemmis and Hallberg (1984, p. 889) try to excuse previous interpretations by saying: “We feel that competent glacial geologists have always tried to evaluate glacigenic sequences based on the best available depositional models at the time of their study.” What they are saying, is that the interpretation of field data is filtered by, and interpreted by, models. This influences the “data” that are seen, as well as those which are reported. The multiple glaciation model is one of those models, and the glacial evidence has been automatically fitted into it. This is one good reason to give little emphasis to local data, and to be skeptical concerning the number of presumed glaciations.

One would think that borehole data, especially in areas with no vertical exposures, would greatly aid a three-dimensional interpretation of glacial sediments and show distinct till layers over large areas. This has not been the case (Eyles, 1983, p. 11). Nilsson (1983, p. 167) says that details of classification schemes that depend upon borings should be viewed with skepticism, because coastal cliff exposures reveal it is often difficult “... to establish a reliable stratigraphy in formerly glaciated areas because of disturbances induced by post depositional ice action.” The Alpine Model and the Reinforcement Syndrome The alpine model did more to cement multiple glaciations in the minds of scientists than any other development. If you ask most laymen-and even some scientists today-how many ice ages occurred in the recent past, they would tell you four. The four-ice-age concept is derived mainly from the alpine model which was developed in the Swiss Alps at the turn of the century. This model was replaced in the 1970s by another model, the astronomical model, according to which the alpine model is now entirely wrong. Looking back on the development of the alpine model, its scientific basis, and its acceptance, provides considerable insight into the methodology in this field, and the influence of a few prominent individuals on two generations of scientists.

How did the alpine model develop? By 1885, Albrecht Penck had developed a method that he thought determined the number of glaciations. He connected gravel terraces along river valleys north of the Alps with end moraines farther south in the foothills. By counting river terraces, he arrived at the number of glaciations. At first, he was able to identify only three gravel terraces and connect the two lower terraces to end moraines. Later, he managed to find another river terrace and connect all four to end moraines (Bowen, 1978, pp. 10, 13; Imbrie and Imbrie, 1979, pp. 114, 115). The publication, in 1909, by Penck, along with Eduard Brückner, of their classic results, solidified opinion on the concept of four ice ages. Others later added more substages to the four-ice-age scheme by claiming some terraces were compound. The purpose of this was to harmonize the alpine data with the astronomical model of ice ages, which claims many more than four glaciations (Bowen, 1978, p. 18). The alpine model became so influential, that all data worldwide were interpreted according to it, whether it fit or not. This is called the reinforcement syndromes-the initial discovery of a phenomenon exerts a powerful influence on subsequent research. All published data were fitted into the alpine model so well that there appeared to be no contradictions (Oard, 1985, pp. 178, 179). Watkins (1972, p. 563) writes:

Perhaps, the best known, or at least most significant, result of the “reinforcement syndrome” in the geological sciences is the very firmly established concept of four glacial periods during the last Ice Age. The initially defined system was confirmed by many different studies.

After stating some of the serious problems faring Quaternary investigators, and referring especially to the alpine classification, Bowen (1978, pp. 7, 8) corroborates:

Indeed it could be said that force-fitting of the pieces into preconceived pigeon-holed classifications is what is almost a way of life for the Quaternary worker.... Tendencies to oversimplify in this way lead to new discoveries being forced into a pigeon-holed classification. Such arbitrary methods tend to perpetuate an illusion of security and precision in an apparently repeated confirmation of the original model. This tendency to confirm discoveries from limited amounts of data has been called The Reinforcement Syndrome The reinforcement syndrome continues in ice age research today, but with a new model-the astronomical theory.

Looking back on the alpine classification, glacial geologists are more free to point out its errors. Many problems of interpretation can readily be seen. For instance, the gravel terraces are usually not continuous along the edge of the rivers, but are highly dissected due to erosion (Bowen, 1978, pp. 13-16). It is, indeed, surprising that this kind of evidence could support multiple glaciations. This view is supported by Flint (1971, pp. 643-645), who says that the Alps is a poor area for defining the number of glaciations in the first place, because of the steep slopes and erosion that has destroyed much of the sedimentary record.

Another problem is that the river terraces are poorly connected to the patchy glacial moraines upstream, and Penck and Brückner concentrated on only a few of the river valleys which do not represent the north slopes of the Alps as a whole (Flint, 1971, p. 644). Moreover, the two upper terraces in the four-fold scheme are only small remnants at different elevations. This is probably the reason for Penck’s early results supposedly verifying first three, then four glaciations. The alpine ice ages were separated by morphological criteria applied to the gravel terraces, and not by time data. There was little or no evidence representing interglacial time (Bowen, 1978, p. 10). The later discovery of peat, warm climate mollusks, and soils within the “glacial” gravels caused much confusion. The river terraces are now claimed, by some, as due to uplift of the Alps: “Kukla (1977) demonstrated that the fourfold sequence in the Alps may be a result of repeated tectonic uplift cycles, not widespread climatic change per se” (Eyles et al., 1983b, p. 217).

Since the gravel terraces cannot be related to any time scale, they could have formed rapidly (as indicated in Chapter 6). Bowen (1978, p. 17) even states:

Moreover, from what is now known about glacial pulse [sic] during the Pleistocene it could be argued that each end-moraine and its associated outwash terrace only represents a few thousand years at most of one cold stage or glacial cycle.

Bowen is speaking about new ideas on glacial oscillations within one glaciation, while still interpreting the time of formation of the terraces mostly within the uniformitarian framework of long ages. If the terraces could have formed as quickly as Bowen proposes during one glaciation in the greatly stretched-out uniformitarian time scale, they could have formed very rapidly during one rapid ice age (see Chapter 6). The main point to be learned from the debate on the number of glaciations, especially in the alpine model, is that the number of glaciations proposed in the past has always been arbitrary, and based on poor evidence. The glacial deposits are so complicated, the number of glaciations is difficult to determine. The available methods for analysis of the observations have serious problems, and misinterpretation is easy. There is physical evidence for fewer than four, as Charlesworth’s more objective appraisal indicates. The number of glaciations recorded by continental deposits is still an open, scientific question.

Evidence for One Ice Age

Perhaps the strongest evidence against ice ages repeating every 100,000 years is the uniformitarian principle itself, As discussed in Chapter 1, Williams (1979) showed that a temperature drop of 10 to 12°C, and double the winter snowfall would be required just to glaciate northeast Canada (Figure 1.3). If one ice age is this difficult to account for, what are the odds against two, three, or 30 in succession? In the standard explanation of glaciation, an ice sheet develops in the far north, grows large, and moves outward to the southern periphery. In its advance from the far north, the ice sheet picks up debris at its base, and transports this debris southward. How far this debris is transported before deposition, depends upon the distance upward in the ice the debris is entrained, the velocity of the ice sheet, and the amount of basal melting. Each successive ice sheet should continually transport the debris farther and farther south. Since most of the debris is from the last ice age (see below), each ice sheet must have been able to totally incorporate almost all this debris. (Almost complete reworking of deposits from previous glaciations is the reason many investigators claim that the continental sediments are unreliable for determining the number of glaciations, and hence urge reliance on the indirect record from ocean sediments.) Some investigators now believe that ice sheets moved relatively fast (Boulton, 1986). Thus, we would expect to find a large amount of glacial till that has been transported long distances from the north. Is this what we observe? Other than a small number of “far-traveled” erratics, practically all the glacial deposits are local (Flint, 1971, pp. 110, 152, 190; Whillans, 1978). Flint (1971, p. 174) writes: The average distance of travel of the components of till is not known. It was long ago established that much of the coarse fraction consists of material of fairly local lithology, and this led to the belief that till as a whole is of predominantly local origin. The fine fraction, of course, cannot be used to identify provenance, because it is mostly crushed quartz and feldspar, which is common to many rocks. Flint generally accepts the local nature of most tills, but seems confused, due to the presence of far-traveled erratics. Admittedly, far-traveled erratics are a problem for a one-ice-age model, but there are problems of interpretation, and some seemingly contradictory data on these exotic rocks, which will be discussed in Chapter 9.

Other workers substantiate Flint’s comment on the local origin of most glacial till. In referring to the Canadian Arctic, Bird (1967, p. 107) declares: “The majority of tills are derived from bedrock in the immediate vicinity.” Feininger (1971, p. C79) indicates that the evidence for the short transport of till is solid, by the following comment:

Earlier in this report, the nearness of most glacial boulders to their source was cited as evidence that glacial transport is generally short. Even stronger evidence to support this view can be read from the tills themselves. Where the direction of movement carried a continental ice sheet from one terrain to another of markedly different rock type, the tills derived from each terrain are predominantly restricted to the area of their corresponding source rocks.

We have been discussing North America, but the same holds true for the Scandinavian ice sheet. Most of the till in Norway and Sweden is local-moved not much farther than about five kilometers (Haldorsen, 1983, p. 11; Lundqvist, 1983b, p. 83). The local nature of most till is not what one would expect, even with a standard uniformitarian interpretation for only one ice age. Efforts are being made to explain this contradiction (Whillans, 1978), but the evidence favors one relatively thin ice sheet that did not travel far, but grew in situ and melted after a short time.

Further indication of only one ice age is provided by the fact that practically all the till was laid down during the last of the uniformitarian sequence of ice ages. Moreover, most of this till is from the last advance of the last ice age (Flint, 1971, p. 641; Sugden and John, 1976, p. 133). The main reason for this conclusion is the fresh appearance of most of the till. Intensive search has been focused to find till from previous ice ages. (In view of the strong desire to find till from previous ice ages, and in view of the complexity of glacial debris, it is surprising that so little success has been claimed. From the viewpoint of the post-Flood model, the limited success is not surprising.) The amount of such material “discovered” is very small. Sugden and John (1976, p. 138), in reference to glaciations other than the last, state: “We shall not, therefore, consider these glaciations in any detail-a task which would in any case be difficult because of the scarcity of supporting evidence.” Uniformitarian scientists commonly appeal to extensive erosion to account for absence of till from earlier glaciations. A popular analogy, credited to Maurice Ewing, likened each continental glaciation to an eraser. Each successive ice sheet erases all, or most of the evidence for the previous ice sheet, making the evidence analogous to the ephemeral writing on a blackboard.

If this is the case, an enormous depth of till should have accumulated at the periphery, much of it indicating long-distance transport from the north, but there is little evidence for either deep accumulations or far-traveled debris. A straightforward reading of all the evidence, without resorting to added hypotheses, better indicates that the main volume of till is the result of just one ice age, which was not only the last, but also the first. In addition to the till, most of the loess south of the ice sheets is also from the last glaciation, at least in North America (Flint, 1971, p. 258; Pye, 1987, p. 245). With loess, ice-age authorities cannot appeal to extensive erosion and reworking by an ice sheet to account for the lack of loess from previous glaciations. The character of the till left in the interior regions, like Canada and Scandinavia, is especially revealing. Interior regions are areas where each successive ice sheet is believed to have built up to over 3,000 meters high. We would expect to see a moderate amount of till in these areas. Just the last thick ice sheet, slowly melting northward through Canada for thousands of years, should have left behind thick, fine-grained till. The opposite is observed. The till is only two to ten meters thick, on the Canadian shield, and is found mainly in depressions, and partly deposited by streams (Eyles et al., 1983b, p. 227). The till is also coarse-grained, suggesting little transport and reworking. A similar pattern characterizes Scandinavia. Haldorsen (1983, pp. 11-13) states that till, in Norway, is not extensive, and, where found, is coarse-grained, and averages less than five meters deep. Till depth averages five to 15 meters in Sweden, and two to three meters in Finland (Flint, 1971, p. 150). Moreover, this till is predominantly from the last ice age (Lundqvist, 1983a, p. 77; 1986, p. 251; Bjorlykke, 1985, p. 198). This puzzling state of affairs is no longer explained by enhanced erosion with deposition further south, but by ineffective deposition on the shield (Eyles, 1983, p. 4). The new explanation does not fit the evidence any better than the old one did. Observations on modern glaciers show that even if only one thick ice sheet melted northward through Canada, great erosion and till deposition would result. Due to the thickness of the supposed ice sheets, which insulates the base from the cold atmosphere and allows geothermal heat to warm the base, some investigators now assume that, on the Canadian shield, the ice sheet was wet-based (Eyles et al., 1983b, p. 226). Motion would be more rapid and erosion more intense with a wet-based glacier than with a cold-based one.

Interior regions received very little erosion from all the presumed glacial activity. The crystalline bedrock of the Canadian shield is of moderate relief, and only slightly planed down by glacial abrasion. Whether the crystalline rocks are underneath a cover of sedimentary rocks, or exposed, as they are in most regions, the bedrock relief is similar. This demonstrates that there has been little erosion from glacial ice. Flint (1971, p. 115) has noticed the evidence of slight erosion of the Canadian shield, and further adds:

Local evidence of slight depth of glacial erosion has been reported from many different districts.... Indeed, the detailed adjustment of drainage to lithology, long antedating the glaciation and yet not destroyed by that event, is a feature that characterizes wide arms of the Canadian Shield.

Flint (1971, pp. 114, 115) believes that erosion of Scandinavia must have been tremendous. This is inconsistent with the evidence from Canada. Other more modern studies, however, indicate Scandinavia was also only slightly eroded (Haldorsen, 1983, p. 11). The explanation offered for this slight erosion is the dominance of resistant bedrock types in Scandinavia. So we are asked to believe that the many presumed ice sheets that have developed and melted northward in interior regions, neither eroded nor deposited much debris! A better explanation is that the thinness and coarseness of the till, and the slight erosion in interior regions, was the result of only one slow-moving, thin ice sheet that developed in Canada and Scandinavia. The main “proof” of multiple glaciation actually comes from the periphery of the ice sheets (Sugden and John, 1976, p. 139). Andrews (1979, p. 208) states that areas of thick glacial “... deposits are really restricted to a belt about 300km wide which extends inward from the ice limits.” This area will be examined more closely. Though thicker than in most locations, the till in this area is not excessively thick. Flint (1971, pp. 149-151) gives the average till thickness for many localities. Iowa averages about 52 meters, Illinois 35 meters, Central Ohio 29 meters, central New York 18 meters, southwest Alberta 15 meters, the Great Lakes region 12 meters, and New Hampshire ten meters. In general, the thickest deposits are close to the edge of the Laurentide ice sheet south of the Great Lakes area, and thinner in all directions from there. The thickness along the edge of the Scandinavian ice sheet is not much different. Flint lists glacial debris thickness in Denmark ranging from 20 to 40 meters. More recent figures are about ten meters higher, but about 65% of this is glaciofluvial sediments (Nielsen, 1983, p. 193), which usually have been considered as “till” by most glacial geologists. In fact, Eyles and Eyles (1983, p. 152) indicate that substantial amounts of continental till are actually glaciolacustrine sediments. Thus, the average till thickness for the whole periphery of both the Laurentide and Scandinavian ice sheets is not over 30 meters, and much of this till does not represent the glacially eroded debris of land-based ice sheets. This is exceedingly thin, for all the presumed glacial activity, especially in view of the likelihood of the ice sheets incorporating unconsolidated pre-glacial surface deposits (Feininger, 1971). The till thickness is much greater in buried valleys and some end moraines. Flint’s list includes several maximum thicknesses of till in the 150-to-400 meter range. These examples are predominantly in buried valleys, which would be natural traps for glacial debris. Flint (1971, p. 149) comments on these areas: “The largest values in Table 7-A occur in buried valleys, and represent ancient valley fills. Other areas of thick drift occur in massive end moraines....” In an analysis of mechanisms for till deposition, the average is what counts.

How much time would be required for an average of 30 meters of till to accumulate, assuming none of it is glaciolacustrine or pre-glacial regolith? To answer this question, many variables must be considered, such as whether a glacier is cold-based or wet-based, moves rapidly, is subject to surges, etc. Glacial-till can be deposited rapidly, under the right circumstances. Flint (1971, p. 149) states:

Volume of deposited drift is determined by load, velocity of flow, and time. With high load and velocity values, the time can be short. For example the Sefström Glacier in Spitsbergen built a pile of till 30m thick in less than 10 years.

Goldthwait (1974) summarizes 16 years of observations of ice wastage in Muir Inlet and outer Lituya Bay, of Glacier Bay, Alaska. Discounting the rates of formation deduced from C-14 dating of wood, directly observed rates of formation of many glacial features, which could be analogous to glacial features in North America, were rapid. Basal till accumulated at 0.5 to 2.5 cm/yr. Each till sheet of about one-to-five meters thickness represented about two centuries of erosion and deposition. Minor moraine ridges abound in the area. They are 0.5 to 2.5 meters high, and each was deposited in one to five years. Meltwater channels were observed to erode rapidly. Most impressive was one stream with a flow of only 200 cubic feet per second on many summer days, yet cut into bedrock at a rate of one to two meters a year. A seven-meter-high esker probably formed in just five years. Kame terraces developed in a year or two.

These observations from modern glaciers, although rapid according to assumed rates for a uniformitarian ice age, are still too slow for a 700-year ice age. But the post-Flood ice age cannot be compared directly with modern glacial features. Evidence that the flow velocity for the ice sheets was significantly greater than for the preponderance of modern glaciers will be presented later in this chapter. A higher erosion rate would be associated with a higher velocity. For a comparison, consider the erosion rate on Glacier d’Argentière in the Alps, as measured by a marble platten attached to bedrock beneath the ice (Drewry, 1986, p. 84). The observed erosion rate was 3.6 cm/yr at a glacier flow rate of 250 meters/year. Another wet-based glacier in Iceland, with a much slower flow velocity, eroded at a much smaller rate. Since a post-Flood ice age would most likely have higher erosion rates, a 5 cm/yr rate might be assumed. At this rate, 30 meters of till could be deposited along the periphery, in 600 years. This does not take into account the loose, pre-glacial surface material that must have been incorporated into the till, or the significant proportion of this till that would be lake or stream deposits. In view of these considerations, one wonders why the till along the periphery is so thin, if 20 to 30 ice sheets repeatedly deposited material in this zone for over two million years.

Besides the character of till over the interior and at the periphery, the areas within the periphery, where till is lacking, also point more towards one, than to multiple glaciations. We are speaking of the “driftless areas,” the most famous of which is located in southwest Wisconsin, in small portions of southeast Minnesota, and in northeast Iowa. This area, apparently, was never overrun by a glacier at any time. Other driftless areas are found on the low relief plains of northeast Montana and extreme south central Saskatchewan (Lemke et al., 1965, p. 16; Mathews, 1974, p. 39). These driftless areas are depicted in Figure 7.1, along with the boundary of the four postulated ice ages in the central United States. These driftless areas should have been covered, at least once, by a thick ice sheet descending out of Canada, according to the uniformitarian model. Even one thin post-Flood ice sheet may have trouble explaining why these driftless areas were not glaciated. But how could many thick ice sheets all miss these areas, if, indeed, there were many thick ice sheets?

Figure 7.1 <C:\Program Files\e-Sword\Graphics\ICE\147.jpg>    Extent of Four Classical Ice Ages

Extent of the four classical ice ages in the central United States. Note the driftless areas in southwest Wisconsin and northeast Montana (after Flint, 1971, and Lemke and others, 1965). Not only does the character of the glacial till better support one ice age, but also, the animals and plants that lived at the time give similar support. The fossils are generally the same in each postulated interglacial period between each theoretical ice age (Charlesworth, 1957, p. 1025). Flint (1971, p. 376) states:

Nevertheless, in Quaternary strata correlation by means of fossils encounters special difficulties. Rates of change of Quaternary environments were generally more rapid than rates of evolution in Quaternary organisms. The same faunas may appear repeatedly in successive strata, and their transgression of time is commonly evident. With respect to the flora, Bowen (1978, p. 38) acknowledges: “The fact is that similar constellations of species were repeated several times in the Pleistocene, though not perhaps in the same relative abundance.” Sutcliffe (1985, p. 52) also concurs. In other words, few fossil criteria are available to distinguish between each particular interglacial. We would expect sizable flora and fauna differences between each interglacial, because the severe stress of the ice ages should have caused significant evolutionary changes (assuming the theory of evolution is true), and because of the many variables that should influence animal distributions over long stretches of time. Although the standard explanation is to simply postulate slight evolutionary changes, the data fits a single ice-age model more reasonably.

Secondly, practically all the fossils are found in nonglaciated areas. Animals and plants should have repopulated interior areas, after each ice sheet melted. The musk ox and reindeer would surely migrate back to the northland, after each glaciation. During the long interglacials, abundant bones, or fossils of cold-tolerant animals should have been deposited. Their absence is, indeed, mysterious within the multiple glaciation hypothesis. The claim may be made that animals simply did not become fossilized during interglacials. This contention is hollow, because the numerous fossils found in the muck of Alaska are attributed to an interglacial period. With respect to the fleet mammals, Flint (1971, p. 771) states: “The general rarity of fossil mammals in glaciated as compared with nonglaciated North America suggests that the rich Alaskan faunas are probably interglacial.” The climate south of the ice sheets during each presumed glacial epoch, probably would have been similar to the climate over interior areas during interglacials. Many fossils are found in the former areas. Their lack in glaciated areas strongly suggests that there were no interglacial periods, which means there was only one ice age.

Thirdly, nearly all of the extinctions of large mammals occurred after the last glaciation. Very few occurred after postulated, previous glaciations. Each ice age would have been very stressful to the animals. How could they survive 20-to-30 ice ages, over a two-or-three-million year period, and then go extinct only after the last? The record of extinctions is more consistent with just one ice age. The evidence supporting only one ice age is summarized in Table 7.1. As stated previously, this evidence is mostly general, and large-scale. The meteorological difficulties of accounting for just one uniformitarian ice age (see Chapter 1), the character of the till over interior areas as well as along the periphery, the lack of loess from previous glaciations in North America, and the character of the ice age fossils, all favor one ice age in preference to multiple ice ages.