Part 6

Glacial dispersion followed one of two general laws: First, the great centers or belts from which dispersion took place in apparent disregard of the slope of the ground were areas most exposed to cyclonic activity and resulting precipitation. Second, minor centers of dispersion (or local glacial dispersion) were elevated lands, subjected to uniform precipitation.

Since glacial conditions in the northern hemisphere were removed from southerly towards northerly latitudes, the gradients were increased southerly and decreased northerly from lines of maximum glaciation. Glacial transportation was likewise modified. The reverse of these directions prevailed in the southern hemisphere.

Glaciated areas have been partly relieved of their loads of ice at rates and times proportional to solar exposure, and upon lines parallel with present mean annual isotherms. Wherever remnants of the continental ice sheets of the Ice Age yet rest, this retreat is still in progress from the same cause.

The ascription of great elevations above sea level during the Ice Age is natural, and such apparent greater elevation is due to two causes during this period, whilst due to only one cause during previous eras. As the surface of the earth became subjected to a temperature of 31° Far. under the oceans, and a corresponding temperature under the continental ice caps, contraction and consequent elevation were continued as before; and as snow was piled up upon the continents, water was withdrawn from the oceans; for each million square miles of continental ice cap three hundred feet thick a corresponding three million square miles of ocean was lowered one hundred feet. The continental ice caps already approximately known were too vast not to have lowered the sea level to a marked degree.

The apparent general depression after the Ice Age is as natural. By the melting of the greater portion of the ice caps, and the evaporation of vast inland seas, the sea was approximately restored to the level existing prior to the Ice Age, thus causing an apparent sinking of the land.

The great difference between climatic conditions prior to and since the Ice Age is very marked around inland seas and basins without drainage. Lake Bonneville and Lake Lahontan, in the United States, and the greater area once occupied by the Caspian and other seas, evidence the superior dampness and rainfall antedating the Ice Age. During the control of earth heat the oceans were heated to their bottoms, and furnished moisture enough to keep these great depressions full of water and to support a dense life upon now desert areas. The dry air of the modern era has not only absorbed the water in these vast lakes, and restored it to the oceans, but vaster areas have been converted into deserts by the unequal distribution of heat and moisture under solar control.

PALÆOZOIC GLACIATION.

“Glacial Periods.”

It is probable and may be regarded as a fact that upon certain of the oldest and highest mountains, glaciation was inaugurated during the Palæozoic Era, to slowly disappear by the gradual setting free of earth heat by vast fractures of the crust or to remain as local glaciation until the Ice Age. Isolated glacial deposits of this nature which were independent of solar exposure readily account for the early “Glacial Periods,” which were evidently local phenomena antedating the Ice Age. It is neither logical nor reasonable to interpret the finding of evidences of early local glaciation into a Glacial Period, for local glaciations are found now in the Alps and upon certain peaks of the Sierra Nevada, and even in the torrid zone, but they by no means establish the present existence of a Glacial Period.

Evidences of glaciations antedating the Ice Age are wholly of a mechanical nature--namely, the transportation of boulders, striæ, etc. No corroborative evidence of fossil life of Arctic habits has been found. This is particularly the case of marine fauna and flora, which may be held as the only indisputable evidence of an Ice Age.

Granting that the evidences found be sufficient to establish Palæozoic glaciations, the absence of fossils of an Arctic type proves such glaciations to have been local and possibly of short duration, for had such glaciation been general and of long duration both plant and animal life would have been modified into temperate and Arctic types, as occurred later when general glaciation ensued.

It is apparent that the isotherm 32° Far. could have shrunk for a short period to the tops of mountains and that glaciers could have formed and coursed their way into a sub-tropical growth below; and that these conditions would be removed by the setting free of earth heat with the consequent rise in temperatures.

These changes followed too closely or were too limited in area to permit the evolution of forms of continental life adapted to temperate and Arctic conditions.

Palæozoic glaciations in no way conflict with the demonstration herein given--they are really corroborative of the other facts advanced to prove that prior to the Ice Age solar heat was shut out from the surface. For the evidences of Palæozoic glaciation occur in temperate and tropical latitudes adjacent to fossil life indicative of high temperatures. Early glaciations were dependent only upon elevation, and latitude did not influence their occurrence in any way whatever, and whether in Norway or India these glacial conditions were coexistent with tropical life at a lower elevation and equally independent of latitude.

When the crust became too thick and non-conducting to yield a sufficient supply of heat to hold mean temperatures at a higher degree of heat than 32° Far. this isotherm shrunk to the surface only to be removed by solar heat. Since the position of this isotherm was independent of latitude its intersections with the surface depended only upon elevation, and as the continents lost their heat more rapidly than oceans, the latter were the last to fall to 32° Far.

As in previous eras torrid, tropical and temperate life had existed in Spitzbergen, France and Brazil independent of the latitudes of these countries, so too were glacial conditions equally independent of latitudes. But in the removal of glacial conditions the isotherms of solar climates were necessarily followed.

Thus the Ice Age marks the date at which the climates of the globe passed from the control of earth heat to that of solar heat. The great specific heat of water retained in the oceans, the energy necessary to maintain the cloud shield shutting out solar heat until both land and ocean areas could be equally cooled and contracted, thus ensuring the maximum degree of thickness and stability to the crust. The mysteries of geological climates, interpreted by known laws, applicable alike to all members of the solar system, develop thus into a system beautiful in its simplicity.

Once realize that the surface temperatures of the globe were at one era in the past too high, by reason of internal heat, to permit water to remain upon the surface, and the peculiar properties possessed by the various forms of water and their relations to heat and cold, and follow out these facts to their natural and logical conclusion, and the whole mystery of geological climates clears up and becomes simple.

MATHEMATICAL CALCULATIONS AS TO THE DURATION OF EARTH HEAT.

It would not be proper to make the foregoing interpretation of the cause of geological climates without briefly referring to the various mathematical calculations which have been made by high authorities, and which reach conclusions materially differing from the deductions herein presented.

The arguments of Sir Wm. Thomson and others, to the effect that internal or earth heat could not have affected the climates of the globe, by reason of the non-conductivity of a comparatively slight thickness of crust, are not conclusive. These arguments are based upon:

1. An erroneous assumption of the manner in which heat is lost by a planet, upon which there exists an atmosphere and a fluid possessing the physical properties of water.

2. No account is taken in these calculations of the heat set free by denudations, etc.

3. The conservative action of active exterior sources is not considered.

1. To assume that in a molten or nearly molten planet heat was lost by direct radiation from the heated surface, is to assume a mode of loss that could not possibly occur with the constitution of our planet, nor with one possessing a constitution generally similar.

At the period assumed as the starting point of these calculations the earth’s crust was just forming from the molten state. At this period, which has undoubtedly existed, all uncombined water must have been evaporated, and must have existed as an enshrouding cloud, shutting out solar heat and shutting in earth heat. Our planet at this period must have presented an appearance similar to that now presented by Jupiter, whose available internal heat has evidently not yet been exhausted, and upon whose surface evaporation must be kept up by internal heat.

The loss of internal heat by a globe constituted as our planet, must proceed, not by the radiation and loss of heat directly into space, but by the performance of work in the expansion of water to vapor, the exposure of the upper or cold surface of the partly condensed vapor to loss of heat by radiation into space.

The existence of a non-transcalent cloud shield is geologically recorded in most unmistakable terms, as previously explained, by the maintenance of eras of tropical, temperate and frigid climates from pole to pole--irrespective of latitude; by the glaciation of areas over which solar energy, when not thus shut out, was capable of removing glacial conditions and establishing much warmer climates; also by the contrast of geological climates with solar climates, one independent of, and the other mainly dependent upon, latitude.