Evidence for Ice Ages Through 1960
During the 19th century, one of the most influential geologists in promoting the idea that ice ages had occurred was Louis Agassiz. Concerning the early discoveries of glacial deposition and behavior in the mid 1800s by Agassiz and others, the book Ice Ages: Solving the Mystery says:174
What earlier geologists had not understood was that although the downhill edge of an equilibrium glacier is fixed, the rest of the glacier is constantly flowing downhill. In its uphill portions, where snowfall exceeds melting, the flow is rapid and eroded material is not deposited. Over the downhill portion of the glacier, however, where melting exceeds snowfall, the flow is slower and the glacier constantly deposits material on the surface underneath the ice. This material, lodged firmly in place and strongly compacted by the weight of the overlying ice, is called a lodgement till.
When the climate warms, the glacial margin seeks a new equilibrium position. In the case of a valley glacier, the equilibrium position is farther uphill. In the case of an ice sheet, the equilibrium position is farther toward the center of the sheet. But the lower part of the glacier then becomes stagnant. It ceases to flow and gradually melts away. Some of the stones, sand, and other material contained within this part of the glacier are thus released directly from the ice. This layer, called ablation till, is superimposed on the lodgement till. The rest of the sediment is carried away and deposited, as outwash, by streams of meltwater flowing within the stagnant glacier and along its margin.
Geologists in Victorian times were able to determine the extent of glaciers during the ice age by locating the thickest deposits of till. These consist of both lodgement and ablation layers and are known as terminal moraines. It was also discovered that some of the sediments that had been labeled "drift" were, in fact, outwash deposits that had been carried by meltwater streams and deposited in front of the glacier.
It took some time for geologists to discover that similar streams of meltwater operated in much the same way within the glacier -- filling crevasses, subsurface tunnels, and caverns with irregularly shaped deposits of outwash sediment. Small wonder then that Agassiz' friend, Reverend Buckland, had been confused by these deposits. The blanket of sediment that the glacier left behind when it finally retreated was a chaotic jumble of unstratified deposits (those that were transported by the ice and then dropped helter-skelter over the landscape) and stratified deposits (those carried away by water and sorted and deposited in neat layers).
With all of this new information about glacial action at their disposal, it was not long before geologists were able to chart the ice-age world and make a map that showed the extent of the great ice sheets. In North America, the terminal moraine was found to be a continuous ridge, up to 150 feet high, that extended from eastern Long Island to the state of Washington. North of this terminal moraine, the glacial deposits were found to consist mostly of till. South of the moraine was a flat landscape formed by a blanket of outwash deposits.
In addition to plotting the margins of the ice sheets, geologists found that they were able to determine the flow direction of the ice by recording the positions of scratches and grooves that had been incised in the bedrock by moving glaciers. Sample readings taken over a wide area were compiled to give a comprehensive picture of glacial flow. Another way of accomplishing the same objective was to trace erratic boulders to their bedrock source. Then, simply by looking at a map, geologists could see what path the glacier had taken.
All of these techniques were employed not only in North America, but also in Europe, Asia, South America, Australia, and New Zealand. By 1875 this effort had resulted in a global map that told the story of the great glaciers as they existed at the height of the ice age.
The Society would interpret these findings as the result of the Flood. The direction of bedrock scratches and erratic boulder movement indicate a flow generally from north to south in North America. So does the position of the "terminal moraine" across the continent. North of the terminal moraine, the deposits geologists interpret as glacial are a jumble of sorted and unsorted debris, but south of it they are highly stratified. How could this possibly be produced by massive flooding? Everywhere, one would expect to find mostly well sorted deposits, since that is what a flow of water produces, not a jumble of two kinds of deposits. One would not expect to find a pile of deposits in a nearly continuous line across the continent, a pile that looks just like the terminal moraines of Alpine and Alaskan glaciers, but much larger. One would not expect to see a sharp jump from a jumble of deposits north of the moraine, to highly stratified deposits south of it.
The striations in bedrock are evidence against a massive flow of water. Striations occur when something holds a hard object against the bedrock and scrapes it along, following the general contour of the bedrock and holding the orientation of the object fixed. Liquid water cannot do this, but solid ice can. Water tumbles rocks along, so that they crash into and bounce off the bedrock. The result is a chipped surface, like that produced by sandblasting, rather than a grooved surface. A look at the bedrock in any stream bed confirms this; you don't find striations. In fact, if striations existed at one time, water tumbling rocks and gravel across bedrock would obliterate them. Furthermore, striations are not found in the bedrock of Washington's channeled scablands.
Another line of evidence against a Flood is seen in the way flowing water drops a load of debris. A massive flow of debris-laden water drops its load whenever the flow velocity decreases. Can you think of what would cause a continent wide flow of Flood water to suddenly drop in velocity at roughly the same latitude all across North America, in such a way as to produce the observed deposits? A large flow of water can slow down for only two reasons -- it ceases traveling downhill or it enters an area where it can spread out. Did the Flood water suddenly stop going downhill or start spreading out somewhere at about the same latitude all across North America? If the Flood were global, where could the Flood water spread out to? The continent-wide terminal moraine, showing lobed features, is much more consistent with the glacial theory than the Flood theory. The morainal pattern is not consistent with debris dropping out of a continent-wide Flood.
What about all the features of a massive flood that I've shown previously in connection with the Missoula floods? Where are they found in Canada and the United States? Where are the giant ripple ridges that should have formed transverse to the direction of flow? If the moraines and other deposits were formed exclusively by flowing Flood waters, why is there no foreset bedding evident in the deposits? Why do they look like deposits you can see for yourself at the foot of retreating Alaskan glaciers?
In older publications, the Society explains the depositional features called kames, eskers and drumlins as features of Flood deposits. However, a careful analysis of these features shows they are produced by glaciers, and only by glaciers. Photographs of kames and eskers at the foot of retreating Alaskan glaciers, in Earth175 and in Living Ice,176 are unequivocal evidence that they are formed by glaciers. Landprints says:177
While the origin of kames and eskers was long a puzzle, the processes apparently responsible for their production can be witnessed along retreating glaciers in Greenland and Alaska. In Alaska's Glacier Bay one can walk along an esker to the front of the glacier that made it and into the tunnel under the ice where it is still being formed.
Drumlins are hills with their long dimensions aligned parallel to the flow of ice. A striking photo of a drumlin field appears in Living Ice178 on page 144. Associated with the drumlins are long striations in the ground, also parallel to the drumlin's long axes. Similar features associated with the retreat of a massive Alaskan glacier are shown in photos on pages 141 and 151 of Living Ice. I know of no process associated with massive flooding that could form such features, and form them in a such way that they look identical to features directly observed to be formed by glaciers. Actually, massive flooding would destroy them, and instead form features such as are found extensively in the Missoula flood region, such as transverse giant ripple ridges. The Missoula flood area contains no kames, eskers or drumlins.
While the origin of kames and eskers is well known and there are places where they can be seen forming today, no one has come up with a universally accepted theory of drumlin formation, nor have they been seen forming in association with present day glaciers. Some have pointed this out as a problem for the theory of ice ages, but it is even more of a problem for the Flood theory. Extensive laboratory studies have been made of what happens as water flows over sand and gravel. At increasing flow velocities, various forms of ridges come and go, always transverse to the flow. Drumlin shapes, with the long axis parallel to the flow, are never observed.
The lack of a theory for a mechanism of formation of one minor feature of continental glaciation is not much of an argument against the overall idea that glaciation has occurred. When Alfred Wegener proposed the theory of continental drift, many geologists refused to accept it because Wegener could not come up with a plausible mechanism to drive the drift, even though the theory explained other phenomena that no other theory could. "How could solid rock continents plow through ten mile thicknesses of ocean crust?" they said. Yet today the speed of continental drift is directly measured using astronomical techniques.
Erratic boulders, too, show evidence of transport by ice. In upstream areas of the Missoula flood region, huge rocks that were transported, not by ice rafting but by the floods, showed a combination of features -- much rounding and abrasion, as well as the angular features due to cracking in high speed impacts in the flood. Erratics in glaciated areas tend to show little or no rounding, even when house sized. Can house sized erratics be transported by glaciers? A photo on page 120 of Living Ice of one sitting on the Malaspina Glacier in Alaska proves they can.
Time-Life's Ice Ages179 has an interesting comment on erratics and glaciation in general:
.... the last effective resistance to the glacial theory withered in the mid-1860s, after the Scottish geologist Thomas Jamieson published a persuasive paper that compared the observed effects of flooding and glaciation, and showed that only glacial action could account for the erratic boulders and striated bedrock found in Scotland.
The thickness of the ice-age ice sheets can be estimated. Ice Ages: Solving the Mystery tells how it was done in the 19th century:180
Geologists accomplished this by determining which mountains bore evidence of glaciation during the ice age and which did not. If a mountain top had been covered with ice, then the ice itself must have been at least as thick as the elevation of that mountain. An even more accurate assessment could be obtained from mountains (such as Mount Monadnock, New Hampshire [3165 ft.]) that had been only partly submerged by the ice sheet -- their rocky, unglaciated summits protruding through the ice to form islands of rock in a sea of ice. Today, the landscape changes abruptly part way up such mountains. Below the critical point, the mountainside is smooth and even; above it, the topography is rough and uneven. The thickness of the ice sheet could be determined simply by finding the altitude of this critical point above the surrounding countryside.
This boundary line on some mountains is instructive. First, the existence of a boundary at all shows that if it were caused by the Flood, then the Flood was flowing at least that high. Since the boundary is found up to elevations of about one mile, the Flood must have been at least that deep. But this gets back to sticky problems about where so much water came from, whether high mountains existed before the Flood, and such, that I've already discussed. Second, the pattern of the landscape on either side of the boundary is reversed from what would be caused by a flood. The geological observations in the Missoula flood region showed that below the high water line, the bedrock was severely plucked and scoured, whereas above the line the previously existing soil was left untouched. But below the glacial boundary line, the bedrock shows glacial polish.180a Above the boundary the bedrock is rough and uneven. Below the boundary are found the grooves and striations typical of Alpine glaciated regions. These features are never found on bedrock that has been polished by flowing water, such as on bedrock streambeds. Bedrock polished by water has a distinctive sandblasted look, different from the sandpapered look of glacially polished bedrock.
During the ice ages, mountain glaciers grew much larger than today, and glaciers were present on mountains that are today ice free. Their growth and retreat occurred simultaneously in both hemispheres. The evidence for this is explained in Earth:181
Much of the kind of rugged mountainous terrain that has been celebrated for its scenic beauty is the product of glacial erosion. The Sierra Nevada, the Cascades, the Rockies, and the Alps all have high valleys that were filled with glaciers just a little more than 10,000 years ago, as evidenced by the signs we have learned to recognize; striations, large blocks carried from high in the mountains, moraines, and cirques. In the mountains of northern California, Oregon and Washington, there are now only small relic glaciers left in the few places that receive enough snow and stay cold enough to preserve ice all year round. The rest of the terrain is exposed, and we can see the effects of Pleistocene glaciation. Farther north, in Canada and Alaska, glaciers become more numerous, but some of the ice-sculptured topography is still exposed.
As glaciers ate away at the mountains, the topography acquired a distinctive appearance. Cirques were formed at the heads of glaciers by ice plucking and undercutting the highest peaks and ridges. Adjacent cirques gradually met to form knife-sharp divides. The result is a jagged, serrated, linear crest. The valleys were excavated to a characteristic U-shape, with steep walls and a flat floor, as the glacier scraped and rounded off irregularities. As the ice retreated, hanging valleys of glacial tributaries were exposed. Lakes formed in depressions in cirques. Most spectacular are the fiords, arms of the sea that occupy U-shaped valleys that were cut below sea level by valley glaciers descending from coastal mountains.
Lakes sometimes offer clear evidence of glacial times in the annual sediments that form on the bottom. Time-Life's Ice Ages182 explains how a Swedish geologist, Baron Gerard de Geer, obtained the first data on this sedimentation:
During field work in the Stockholm region, de Geer was struck by the regularity of the laminations in the sediments at the bottoms of lakes fed by glaciers. When glacier ice melts during the summer, de Geer discovered, the meltwater carries off a load of debris that settles in the nearby lake to form a distinct profile for that particular year. The heavy material sinks first, forming a coarse layer, while the lighter material remains longer in suspension, eventually accumulating as a fine sediment on top of the coarse deposits.
Since glacial lakes are born as soon as the glaciers retreat, de Geer was able to estimate the age of each lake -- and thus the approximate date of the glacial recession from that locality -- simply by counting the pairs of sediments, called varves, on its bed. In addition, because varves vary in thickness according to the climate, being thickest in warm years when melting glaciers release large quantities of sediment, de Geer was able to plot the progress of the Scandinavian Ice Sheet's retreat by correlating the sediment patterns of different lakes. He calculated that the oldest lakes -- those nearest the margin of the ancient ice sheet -- had been formed approximately 12,000 years ago, while the youngest were little more than 6,000 years old. And the fluctuations in the thickness of the varves gave him a crude picture of the climatic record since the retreat of the glaciers.
Note that the dating of the varves is done by counting them. This dating method is independent of, and confirms, the dating of glacial features by radioisotope methods. The method does not suffer from some of the problems of tree ring dating, as the varves form a continuous sequence in many different lakes and give consistent answers.
After discussing radioisotope dating, The Innocent Assassins discusses dating with varves:183
Radiometry has given us a firmly based time scale for the history of the earth.
Well and good. But the lay reader may object that this is an esoteric method and that it would be rather nice to see something simpler -- more obvious. For instance? I reply. Something I can see, the reader might say; something like tree rings.
Yes, why not? The earth does have annual rings, just like trees. And the interesting thing is that they give time scales that are in excellent agreement with the radiometric ones.
The first to be developed was the glacial clay "varve" or band chronology, which was introduced by the Swedish geologist Gerard De Geer.... At the beginning, it was a "floating" chronology -- that is, it was not connected with the present day. This has now been rectified, especially by studies in the valley of Angerman River in northern Sweden, where Ingemar Cato was recently able to close the last remaining gap. And so there is now an unbroken sequence of annual varves taking us nearly 13,000 years back in time.
The glacial varves, which may be a centimeter or more in thickness, are usually easy to observe. But there are also much thinner varves, perhaps only a fraction of a millimeter in thickness. Such varves, or lamellae, are formed in the bottom sediment of certain types of lake, which have been studied especially in Finland. This happens in "poor" lakes (technically termed oligotrophic) where there is no bottom fauna to poke about in the sediment. When studied microscopically, the varves are, again, seen to result from seasonal changes -- the spring flowering of microscopic plants called diatoms, changes in the chemistry of the water, and changes in the supply of inorganic sediment.
They too are annual "rings" that can be counted and used in a chronology (if the lake is still in existence, the chronology of course will extend all the way to the present). The difference is that all the varves are piled on top of each other in a single lake basin, so that you do not have to move from place to place to construct your time scale, as is the case when you track series of ice-dammed lakes that followed the retreating ice margin. In this case, certain lakes too give us a long chronology; Lake Valkiajarvi in central Finland, which was studied by Matti Saarnisto, carries us back almost 9,500 years in time, to the birth of the lake after the melting away of the inland ice in this area.
Another type of evidence for glaciation that geologists have extensively studied is the depression of sea level during an ice age. Ice Ages: Solving the Mystery184 explains:
.... geologists in Scotland and Scandinavia found abandoned sea cliffs and other shore-line features indicating that sea level during the ice age was indeed much lower than it is today. And, in some places, they also found evidence that sea level immediately following the retreat of the glaciers was higher than it is today. This high shoreline is especially apparent in Scandinavia where, in the center of what is today a mountainous region, marine shell deposits are found at altitudes higher than 1000 feet. The Scottish geologist, Thomas F. Jamieson, was the first to interpret these marine deposits correctly. In 1865, he wrote that:
In Scandinavia and North America, as well as in Scotland, we have evidence of a depression of the land following close upon the presence of the great ice-covering; and, singular to say, the height to which marine fossils have been found in all these countries is very nearly the same. It has occurred to me that the enormous weight of ice thrown upon the land may have had something to do with this depression.
Jamieson went on to suggest why this depression would occur. He postulated that underneath the earth's outer, rigid crust was a layer of rocks "in a state of fusion," which would flow under pressure.
This bold and original speculation was supported years later by geophysical measurements. Just as Jamieson suggested, the upper portion of the earth's crust was shown by the measurements to be floating on fluid material. When a quantity of ice is placed on the earth's surface, the crust sinks down -- exactly as the addition of passengers in a rowboat causes it to ride lower in the water.
The shorelines of glaciated regions, therefore, tell a curious story of marine inundations. During the ice age itself, worldwide lowering of the sea level caused shorelines to move downward by about 350 feet. Simultaneously, the weight of the ice sheets depressed the land surface underneath them. When the ice sheets melted, there was an immediate response -- a rise in sea level -- and a gradual response -- a slow uplifting of the land surface. Thus, in new England, Scandinavia, and other glaciated areas, deglaciation was followed immediately by flooding. With the passage of time, however, the land surface rose to its original height -- causing the sea level to appear to drop. In some areas of the world, the land is still reacting to the removal of the ice. Around the shores of Lake Superior, for example, the land is rising at the rate of 15 inches per century. But, away from the heavily glaciated areas, the shorelines tell a much more straightforward story, reflecting only the general rise and fall of sea level as water was subtracted from, or returned to, the ocean reservoir.
The rise of the land around Hudson Bay in Canada is about 3 feet a century. See page 245 of Landprints185 for a photo of the changing beachline. See also the footnote on page 16 of the section on the polar regions for further comments about changes in sea level.
A large area of the earth's surface is covered by fine sediment called loess. Some places such as China are blanketed by as much as several hundred feet. Ice Ages: Solving the Mystery186 describes early discoveries about the nature of loess:
While some geologists confined their studies to areas that had actually been covered by ice sheets, others investigated land areas away from these regions. These geologists discovered that more than one million square miles of Europe, Asia, and North America had been blanketed during the ice age with a layer of fine, homogeneous, yellowish sediment. Borrowing an old term used by German farmers, they called this deposit "loess" (pronounced to rhyme with "bus"). In some areas, this layer of silt was found to reach thicknesses exceeding 10 feet. In other areas, it was found only in thin, discontinuous patches.
The attention of geologists had first been drawn to this peculiar deposit early in the nineteenth century, but its origin had remained a mystery. The fact that loess was composed of minute, uniform grains of silt suggested that it might have been deposited by moving water. But the horizontal layering that characterized other water-laid deposits is not present in loess. Moreover, marine fossils are absent. It was not until 1870 that geologists found an adequate explanation for loess. The explanation came from a German geologist, Ferdinand von Richthofen, who published his theory and later defended it to a skeptical colleague:
It is perfectly evident that no theory starting from the hypothesis of the deposition of loess by water can explain all or any single one of its properties. Neither the sea nor lakes nor rivers could deposit it in altitudes of 8000 feet on hillsides. Origin from water is perfectly unable to explain the lack of stratification,.... the vertical cleavage, the promiscuous occurrence of grains of quartz, the angular shape of these,.... the imbedding of land shells, and the bones of terrestrial mammals.
There is but one great class of agencies which can be called on for explaining the covering of hundreds of thousands of square miles.... with a perfectly homogeneous soil.... Whenever dust is carried away by wind from a dry place, and deposited on a spot which is covered by vegetation, it finds a resting place. If these depositions are repeated, the soil will continue to grow.
Von Richthofen's explanation of loess as a wind-blown deposit became universally accepted. Geologists were able to clarify their picture of the ice-age world, and a new piece of the ancient puzzle slipped into place. When melting occurred at the southern boundary of the ice sheet, great quantities of silt were deposited by outwash streams. Because the deposits were neither covered with snow, nor held in place by vegetation, they were easily blown away by the high winds that swirled in front of the ice sheet. Von Richthofen's ideas were confirmed by observations in Alaska, where glaciers melt rapidly during the summer months and the great quantities of silt deposited at their base dry up and are blown away to cover nearby grasslands with fertile loess.
The silt that the ancient glaciers drained from Canada in melt-water streams has proved to be a boon to American farmers in the Midwest. For that silt was blown southwards where it settled and eventually became the rich, easily cultivated, and well-drained soil of America's farm belt.
Another book, Landprints,187 says concerning loess and its formation:
Winds that today blow across the Great Plains are normally (but not always) of modest intensity, painting patterns that sweep across ripening grain fields like flying shadows. During the ice ages the typical winds may have been considerably stronger. The westerlies of today are strongest in winter because that is when temperature differences between the tropics and high latitudes are greatest. The atmosphere itself attempts to equalize those temperatures, causing large-scale circulation, and during an ice age the temperature differences must have been greater and such circulation more intense. Analysis of layers laid down in the Greenland and Antarctic ice sheets during the last Ice Age indicate that the atmosphere then was one hundred times dustier than today.
.... As now occurs along some Alaskan rivers, enormous quantities of meltwater wove an ever-changing, braided pattern across the valley floors, forming broad bars of gravel, sand, and silt that, particularly during dry periods, provided an abundant source of dust for eastward transport by the prevailing westerlies. As a result accumulations of one hundred feet or more formed east of the Missouri and Mississippi river valleys.
The material thus deposited is known as loess.... which is easily tilled -- and easily eroded. The deep accumulations east of the Missouri and Mississippi rivers and closest to the loess sources are known as the Loess Hills.
Their erosion has produced a special kind of landscape found in China and to some extent in other regions of loess accumulation such as the Soviet Union, central Europe, and Argentina....
During the ice ages loess deposition occurred as far east as Ohio and also west of the Rockies in Washington, Oregon, and Idaho. Wind lifted silt from the basins of the Columbia and Snake rivers, leaving coarser material behind and depositing the silt on higher ground to the East. In the rolling Palouse Country of southeastern Washington the resulting loess, mixed with small amounts of mineral-rich volcanic ash, blown east from the Cascade volcanoes, forms a blanket commonly several tens of feet in thickness. Grain harvests there have made the Palouse farmers among the nation's most prosperous. Most of the deposit predates the last glaciation, since it was already there to be swept away when the ice dam of Lake Missoula collapsed.
Genesis 8:1 reads ".... and God caused a wind to pass over the earth, and the waters began to subside." Some have speculated that loess was actually formed immediately after the Flood by this "wind of God" from flood debris. But note several items from the preceding accounts: (1) Dust layers were found in ice cores from Greenland and Antarctica that showed that the ice age atmosphere was far dustier than today. These cores contain thicknesses of ice containing up to 160,000 years worth of accumulation in the case of one core from the Soviet Union's Vostok station in Antarctica. This core represents less than half the thickness of ice over the spot from which it was taken. (2) Loess from before the last ice age was already in place when the Missoula floods swept it away. Now, the ice caps with all their dusty layers, and the phenomena seen in the region of the Missoula floods, could have formed either before the Flood or after it. If they were formed after the Flood, 4400 years ago, one who believes the Flood occurred should be able to explain how the ice caps, up to 3 miles thick in places, formed in such a short time, and also how the numerous phenomena of the Missoula floods region came about. If these things were formed before the Flood, one must explain how ice caps, the ice dam that dammed Lake Missoula, and the loess deposits, were formed in the "hothouse" conditions of pre-Flood days. If one concedes that the earth was relatively cool before the Flood, and ice caps already existed, why did the Flood not break them up and float them away?
Large ice age lakes are another evidence of a very different climate during the ice ages. Ice Ages: Solving the Mystery188 describes some observations:
Geologists working in the American West found evidence that parts of Utah, Nevada, Arizona, and southern California were wetter during the ice age than they are today. In 1852, Captain Howard Stansbury (a topographical engineer who was investigating the flatlands around Utah's Great Salt Lake) wrote these observations in his diary:
Upon the slope of a ridge connected with this plain, thirteen distinct successive benches, or water-marks, were counted, which had evidently, at one time, been washed by the lake, and must have been the result of its action continued for some time at each level. The highest of these is now about two hundred feet above the valley.... If this supposition be correct, and all appearances conspire to support it, there must have been here at some former period a vast inland sea, extending for hundreds of miles; and the isolated mountains which now tower from the flats, forming its western and southwestern shores, were doubtless huge islands similar to those which now rise from the diminished waters of the lake.
Subsequent research confirmed Stansbury's inference. During the 1870s, Grove K. Gilbert of the U.S. Geological Survey showed that the Great Salt Lake is only a remnant of a former and far more extensive lake, which he named Lake Bonneville.... during the ice age, this ancient lake was larger than any of America's Great lakes are today, indicating that the climate in the western part of the United States was not only colder but also significantly wetter than it is today.
Landprints says that through
much of the successive ice ages Lake Bonneville seems to have waxed and waned, as indicated by the steplike succession of its beach lines. Material extracted from a hole drilled more than 1,000 feet into the south shore of Great Salt Lake indicates more than a score of such cycles in the past 800,000 years.189
The caption on a National Geographic photo190 of terraces from Lake Bonneville says:
Ancient beaches behind Utah's copper-domed capitol reveal the lake's fluctuations in prehistoric times. During the past ice age, water began to rise but stalled 22,000 years ago at 4,500 feet creating the lowest terrace.... the Stansbury level.... By 16,000 years ago water had climbed to 5,090 feet, the Bonneville shoreline, before overflowing into the Snake River. The diversion lowered the lake to 4,740 feet, the Provo level, where it remained until 14,000 years ago. The lake has since declined as climate turned warm and arid.
Note that this evidence shows a succession of events -- not a single instance of flooding of a low lying area, as you would expect if the Lake was a remnant of the Flood. On page 700 the above National Geographic article says:
Lake Bonneville peaked at 5,090 feet above sea level. Then it burst its bounds at Red Rock Pass in Idaho, dropping within a year 350 feet to the second, so- called Provo terrace. By 8,000 years ago the lake had evaporated to its modern size.
This draining of Lake Bonneville by 350 feet produced a flood that drained through the Snake River and Hells Canyon, on into the Columbia River. Various books differ somewhat on the dating of this flood, but it was recorded in Snake River sediments in a most interesting way. Cataclysms on the Columbia says that the Missoula floods left deposits in the Snake River Canyon upstream of where the Snake joins the Columbia:191
Floodwaters surging up the Snake River Canyon helped to erode the late lava flows which had partially filled it, and deposited great mile-long gravel bars high up on its walls many miles upstream from the Palouse River junction. One bar a few miles south of Lewiston, over 100 miles from the mouth of the Snake, is exposed in a quarry, and shows the Bretz flood sands overlying coarse gravels previously deposited by the flood which came down the Snake River from Lake Bonneville in Utah.... The foreset bedding in the coarse gravels of the lower part of the bar south of Lewiston dips downstream, while the finer sand rhythmites in the upper part of the bar dips upstream, showing that the Bonneville flood traveled downstream, and the Bretz floods traveled upstream.
Landprints also describes the Bonneville flood on pages 170-171.
In addition to the above mentioned evidence, this sequence of deposits -- first the downstream flowing Bonneville flood deposits, and then the upstream flowing Missoula flood deposits, is strong evidence that the Flood did not occur. The Society claims that freshwater lakes that were at one time much larger than they are today, were remnants of the Flood.192 But the above evidence shows that some of the Missoula floods occurred after the partial draining of Lake Bonneville. Therefore some of the Missoula floods must also have occurred after the Flood. But we have seen that large scale glaciation was intimately involved with the Missoula floods -- Lake Missoula was blocked by a continental glacier, and ice-rafted erratic boulders are found throughout the Missoula flood drainage area. There is absolutely no physical evidence that glaciation on this scale came and went in the 4400 years since the Flood.
Direct drilling into Lake Bonneville salt deposits showed at least 20 cycles of filling and drying up. The drill hole depth of 1,000 feet in the salt is also fatal to the idea that only one flooding of the area occurred. There is no way that a 1,000 foot depth of basically fresh water could have deposited that much salt in under 4400 years. Even a one time filling with pure sea water would leave only a few tens of feet of salt.
Given all this evidence, you should be able to see how misguided is the The Bible: God's Word or Man's? writer's attempt at facetiousness on page 115:
".... there may well be an actual flood of gigantic proportions dating from one of the pluvial periods.... many thousands of years ago." The pluvial periods were times when the surface of the earth was much wetter than now. Freshwater lakes around the world were much larger. It is theorized that the wetness was caused by heavy rains associated with the end of the ice ages. But some have suggested that on one occasion the extreme wetness of the earth's surface was a result of the Flood.
There is plenty of evidence that glaciers have advanced and retreated many times. Concerning some of the early discoveries, Ice Ages: Solving the Mystery193 says:
When the era of exploration began, there were already strong hints that the earth had been glaciated not once but several times. As early as 1847, Edouard Collomb reported two layers of till in the Vosges mountains of France. But these were separated only by stream deposits that could be interpreted either as a record of a short and minor retreat of the glacial terminus, or as evidence of a major and prolonged period of glacial recession. In the 1850s, similar evidence was found in Wales, Scotland, and Switzerland, but the conservative view -- that the intertill beds represented minor climatic fluctuations during a single ice age -- was generally preferred.
In 1863, Scottish geologist Archibald Geikie argued that plant fragments found between layers of Scottish tills were clear evidence that sustained intervals of warm climate intervened between different glacial ages. Finally, in 1873, Amos H. Worthen, Director of the Illinois Geological survey, showed that a humus-rich soil had developed on one till layer before being buried by another. Since soils of this kind can only develop when the climate is warm enough to support abundant plant growth, this was strong support for the supposition that warm interglacial ages had occurred. Only a few years later, John S. Newberry and W. J. McGee clinched the argument by showing that in the American Midwest, two sheets of till were separated by the remains of a former forest.
By the end of the 19th century geologists had gathered enough evidence to conclude that Agassiz had been right -- there had indeed been ice ages. Ice Ages: Solving the Mystery194 says:
By 1875 geologists had completed their initial survey of what the world of the last ice age was like. They had mapped its glaciers; measured its sea level; and determined which areas had been cold and wet, which cold and dry. They had also discovered that the ice age was not a unique event -- that, in fact, there had been a succession of ice ages, each separated by warmer, interglacial ages similar to the present one. With all of this behind them, geologists were ready to turn their attention from facts to theories.
174 John Imbrie and Katherine Palmer Imbrie, Ice Ages: Solving the Mystery, pp. 48-49, Enslow Publishers, Short Hills, New Jersey, 1979.
175 Frank Press and Raymond Siever, Earth, p. 250, W. H. Freeman and Company, New York, 1986.
176 Robert P. Sharp, Living Ice, p. 14,46,77, Cambridge University Press, Cambridge, 1988.
177 Walter Sullivan, Landprints, p. 264, Times Books, New York, NY, 1984.
179 Windsor Chorlton, Ice Ages, p. 89, Time-Life Books, Alexandria, VA, 1983.
180 John Imbrie, et al, op cit, p. 52.
180a Note that glaciers do pluck out bedrock, as well as polishing it. The combination of features -- minor plucking, general polish, grooves, and striations -- is what distinguishes glacial action on bedrock.
181 Frank Press, et al, op cit, pp. 245-246.
182 Windsor Chorlton, op cit, pp. 95-96.
183 Bjorn Kurten, The Innocent Assassins, pp. 84-88, Columbia University Press, New York, 1991.
184 John Imbrie, et al, op cit, pp. 53-54.
185 Walter Sullivan, op cit.
186 John Imbrie, et al, op cit, pp. 54-55.
187 Walter Sullivan, op cit, pp. 265-266.
188 John Imbrie, et al, op cit, pp. 55-56.
189 Walter Sullivan, op cit, p. 172.
190 "No Way to Run a Desert," National Geographic Magazine, pp. 706-707, Washington, D.C., June, 1985.
191 John Eliot, et al, op cit, pp. 121-122.
192 The Bible: God's Word or Man's?, p. 115.
193 ibid, pp. 56-57.
194 ibid, p. 57.