That glacial episodes were quickly followed by long periods of warm climate is, as we have noted, verified beyond doubt by voluminous evidence. Conditions we can see on other planets tip us off as to how and why this came about. Bands of clouds covering those planets are behaving just as Earth’s primordial shroud must have behaved. As the bands of declining primitive aqueous clouds moved poleward from the equator, one after another, they constituted a greenhouse insulating roof or blanket over the globe, to absorb and let in solar heat, but retard its later escape. Thus, after the fall of an increment of snow or ice to inaugurate an ice age, and temporarily refrigerate the Earth, the insulating blanket would, geologically speaking, quickly melt away the ice and establish a succeeding uniformly mild climate, from pole to pole, to endure literally for an “age,” until another sudden downfall of ice or snow would again inaugurate a glacial episode. That such a cycle of warm climate, succeeded by a shorter period of glaciation, has occurred time and time again is generally conceded. No theory previously advanced has even attempted to account for this cycle of climatic fluctuation.
As previously observed, the fact that increases in Earth’s surface waters have occurred within geological time, definitely solves the mystery of subaerial erosion of canyons deep in continental slopes and far below sills of mediterranean seas. The increases account for drowning of mid-oceanic islands, ridges and sea mounts synchronously with submergence of world-wide continental margins. We now comprehend how “land bridges” and “lost continents,” presently submerged, formerly existed to permit spread of floral and faunal species, as well as human cultures, religions and traditions between distant parts of the world now separated by wide expanses of ocean. Flint, in Glacial Geology and the Pleistocene Epoch, gropes for an explanation of how Folsom Man managed to cross from Asia to America over Bering Strait and make his way south to a region where survival was possible, over pathways made impassable by glacial ice sheets. We now realize that man crossed before the land bridge was submerged by increase of ocean waters and before the ice ages of that period eventuated.
It has always been assumed that epeiric seas—former bodies of water in inland continental basins—were caused by subsidence of the involved areas below sea level. However, this theory is nullified by the fact that occurrence of epeiric seas was synchronous in all four quarters of the globe. It can scarcely be thought that simultaneous subsidence of land areas on every continent could have occurred. Alternation of submarine and subaerial fossils and deposits in the beds of former epeiric seas would mean that the land must have been alternately depressed and up-lifted time and again. This would be in conflict with the conviction of geologists that in the main, aside from major orogenic revolutions, continental platforms have been stable throughout geologic time.
Without relying upon the assumption that restricted areas of the continents have bobbed up and down repeatedly to account for such inland seas, does it not seem more probable that these “seas” were in reality lakes formed from deluges of primitive water which filled pre-existing continental basins until the waters overflowed the banks and cut channels to empty the lakes, or remained until they evaporated? Although fossils in the beds are predominantly lacustrine, others are of shallow marine types. The latter can conceivably be accounted for by the conception that the descending primitive waters which filled epeiric seas very probably were saline at times.
The theory that all the salt in oceans and dry lakes was dissolved and transported from rocks and soils on land seems questionable. If such theory is correct, how did the salt originally get in and on the land and whence did it come? Can anyone conceive a source other than the primordial atmosphere? In Chapter Five the origin of salt will be discussed further.
Earlier we learned that among geologists it has always been considered paradoxical that so-called “pluvial” conditions apparently accompanied glacial periods. In harmony with the idea that frozen primitive water descending from space above built the ice sheets, it seems completely logical that either rain or melting snow and ice must have brought about pluvial conditions in global areas where ice sheets did not form.
It is evident that while frozen moisture was falling in some areas to build ice sheets, heaVy rainfall no doubt was occurring in other areas, more or less all over the world. Hence we should no longer be mystified by contemporaneous existence of ice caps in some areas and pluvial conditions in others. We can now understand how the huge basin of central Asia was submerged by a much larger Caspian Sea; how Lake Bonneville in America and countless other “pluvial” lakes were formed and re-formed either by deluges of primordial water or by melt-water from glaciers.
Glacial Ice Changed Climate
Knowing that glacial ice came upon the world stage suddenly, we understand why we cannot find evidence that Earth’s climate grew cold before the advent of an ice age; why, on the contrary, climate grew colder only after the ice arrived and only to the extent that the ice itself refrigerated the Earth, exactly like a chunk of ice chills an ice box. Hence we realize why glaciers began to melt immediately after deposition and why those of the last glaciation are still melting and shrinking, even in polar regions. We know why, although such an inconceivably vast amount of ice would melt exceedingly slowly by human standards, the duration of each ice age was very short geologically as compared with the duration of interglacial epochs.
The new conception throws light upon the mystery of “perma-frost” in high latitudes of Canada, Alaska, Siberia, etc. This unconsolidated soil is permanently frozen to known depths in places of more than a thousand feet. In the absence of a credible theory to explain this phenomenon, the assumption has always been maintained that the ground froze to such astonishing depths because of continued severe cold which caused glacial epochs. Yet it is a scientific fact that ground will not freeze to depths of more than a few feet, no matter how cold the climate. Latent terrestrial heat rising from Earth’s interior, combined with high insulating characteristics of soil, successfully prevent frost from descending to anywhere near the depths of perma-frost.
- The true origin of ice ages
- Earth’s sedimentary crust