Mysteries of glaciation
Displacement of the Poles
To account for the fact that ice sheets, more especially during the Permian epoch, actually formed in the tropics, the explanation has been soberly advanced that the locations of Earth’s poles must have been different, so that regions now in the tropics were then much nearer the poles! No reason whatsoever has been produced to show that the poles could ever have moved far enough to be placed where the tropics are now, much less to show that such a change could have occurred as recently as the Permian epoch. Furthermore, even if the poles in Permian time were situated in present tropical regions, the fact would not account for ice which also accumulated at that time in other areas which under that hypothesis were then temperate. Likewise, in the Pleistocene and other glaciations, ice sheets, in addition to forming in upper latitudes, also accumulated, though less extensively, in or near the tropics. In other words, glaciations were more or less world-wide. Hence the theory of transplanted poles, even if it could be validated, would be completely impotent to offer a solution. The whole idea is purely imaginary and approaches the preposterous.
Highland Centers
The assumption that ice sheets originated upon and advanced from “centers” of high altitude appears to be of doubtful validity. The concept comes from observation of existing mountain-valley glaciers. There is a quite unjustified habit of classing and comparing glaciers which form Cn mountain heights and flow down the valleys with continental ice sheets, which in bygone ages spread unbroken blankets of ice over vast areas of comparatively level land of low altitude and low latitude.
There is no mystery whatsoever about how mountain glaciers formed; in fact, the process is in actual operation today, notwithstanding it is presently too feeble to quite sustain existing glaciers, much less to augment them. However, all that would be necessary to enlarge them would be increased precipitation of snow. On the other hand, occurrence of inconceivably vast continental ice sheets on low, flat lands in temperate zones and conditions which enabled them to form constitute an entirely different problem.
The theory that ice sheets originated on highland centers presupposes that innumerable mountain-type valley glaciers formed on those highlands; that the separate glaciers flowed down and out in all directions; that upon reaching lower, level lands, they spread laterally into “piedmonts”; that the piedmonts coalesced each with others and expanded until finally they constituted a continental ice sheet. It is claimed that thereafter the ice blanket continued to creep, advance and spread until, as in the case of the Pleistocene in North America, it reached south to the 40th parallel, north to the Arctic Ocean, west to the Rocky Mountains and east to the Grand Banks.
As to some ice sheets, there is doubt that centers of origin can be found whose altitudes above sea level were enough to permit accumulation of snow. The so-called Keewatin Center in Canada is such an instance. While it can be believed that snowfall might be so concentrated and so long continued on high mountains that it would form glaciers to flow down the sides and push out for a few miles on low, level lands below, it seems doubtful that snowfall could be so long continued and so narrowly concentrated on a “center” of low altitude in a temperate zone, such as the Keewatin Center, that it would become slowly compressed over the years into ice; that the ice would then gradually creep outwardly in every direction, not only downhill, but likewise uphill, across lakes and canyons, battling also summer heat, until at last it would form an unbroken blanket hundreds or thousands of feet deep, covering an area three thousand miles in diameter!
The writer has spent many weeks, both in summer and in winter exploring and observing mountain glaciers hundreds of miles north of the Keewatin Center. In late fall and early winter, before severely cold weather arrives, heavy snowfalls customarily occur. In summer, however, daytime temperatures rise so high, even at altitudes of several thousand feet, that snow from the previous winter disappears completely, save for occasional deep drifts in sheltered places. Many mountain glaciers descend only to and terminate at altitudes of a thousand feet or more above sea level. Some valley glaciers on the ocean side of coastal mountains terminate before they reach the sea. If climate were colder enough to enable them to reach the sea, it seems probable that snowfall might be too much reduced to nourish them adequately.
Erratic Boulders
Proof that ice of continental ice sheets traveled great distances is supplied by “erratic” boulders whose sources have been found as much as several hundred miles from where the erratics now lie. However, as to erratics found in various regions on Earth—those found, for instance, in southern Ohio, Indiana and Illinois—there is evidence that they may have been “rafted” to their present locations by icebergs drifting in a former glacial lake. Usually the boulders are found in greatest abundance on or near the tops of hills. Often they are found in shallow “pot holes” which appear to have been gouged out by the rocking of melting bergs which stranded near the southern shores of the lake.
There are evidences that in Pleistocene time, at some stage of waning of the ice sheet, a vast lake occupied the above states between the termini of the ice sheets in the Great Lakes region and the Ozark ridge to the south. At that time, the Ozark ridge is thought to have extended east across the Mississippi Valley to the Cumberland Plateau. The present outlet of the St. Lawrence River was either blocked by ice or had not yet been opened through the mountain chain which once extended across the St. Lawrence Valley. The lake rose until it overflowed its southern banks and drained itself through the Mississippi spillway.
There can be no doubt that ice in the continental ice sheets must have flowed to an appreciable extent. Aside from the erratics, proof is also supplied by kames, eskers and moraines which the ice deposited; also by striations it chiseled on rock ledges, beds and boulders. But all such effects could have been accomplished by very little horizontal movement, certainly by much less than fifteen hundred miles.