Part 7

Thus the loss of heat by the crust must have proceeded with great slowness; and the crust in thus cooling was, by the laws of cooling solids, made as thick as possible.

2. The non-conductivity of this cooling crust was a cause of the long, instead of a cause of short duration of the internal heat, for when too thick to yield up its heat by conductivity, additional increments were but slowly set free by denudations, faults and fractures. The volume of heat thus set free may be partly grasped when it is considered that no portion of the crust can be reached that is not built up of denuded materials. Heat imprisoned by a non-conducting crust is more certain of liberation by denudation than if the crust were composed of strata having the conductivity of beaten silver.

The assumption that the low conductivity of the crust was a cause of the short duration of earth heat as a controlling factor is exactly contrary to the actual tendency of such low conductivity.

3. From the cold outer surface of the cloud envelop heat would radiate much more slowly than from the more highly heated surface beneath. Indeed, there is every reason to assume that this upper surface may have been partly composed of fine crystals of ice, as cirrus clouds may now be. Upon this upper surface, whatever may have been its condition, was received every thermal unit of heat reaching our globe from exterior sources from its development to the culmination of the Ice Age. What calculation has considered this single factor? which, for aught we know, may have been but little less than the original available store. To what consideration is any discussion which omits this factor entitled?

Having properly assumed a temperature which would necessitate the evaporation of all uncombined water and its suspension above the heated surface, a scientist should follow the results to their legitimate and logical conclusion, and not neglect the existence of a condition necessarily coexistent with those assumed.

The removal of the enshrouding clouds need not be assumed; such removal was blazed upon the globe in broad zones of climate and life which only solar energy could maintain. These lines are as distinctly different from those written by earth heat as daylight is from darkness.

When this removal did take place the fact was graven upon our planet by the melting of the massive glaciers deposited during and before such removal, and by the establishment of the existing conditions.

All calculations and discussions omitting these three factors must reach illogical and erroneous conclusions. The omission of a single one would be fatal, and entitle the result to no farther consideration, and justifies the cynical view that “There is something fascinating about science. One gets such wholesale returns of conjecture out of such trifling investment in facts.”

ASTRONOMICAL CAUSES AND THEIR INFLUENCE.

We will now consider the effect of astronomical causes. Dr. Croll has elaborately discussed the variations in solar exposure to which the two hemispheres of our planet have been and are subjected.

The distinguished Astronomer Royal of the Dublin Observatory, Dr. Ball, has shown that 63% of the gross solar energy received by either hemisphere reaches it during summer and the remaining 37% during winter. High authorities, both before and since these publications, have discussed various phases of these influences, as well as offered remarkable and unverifiable hypotheses regarding the temperature of space, solar energy, and the heat absorptive power of a solar envelope. It is not necessary to attempt a discussion or elaboration of these views. Should the interpretation herein rendered be correct, it follows that variations in the distance from or degree of solar energy could not have directly affected the surface temperatures of the globe prior to the culmination of the Ice Age, and that only since that age could these slight variations have acted, except in a conservative way. It is unquestionable that for many years past the temperature of the northern hemisphere has risen more rapidly than the southern. This condition is proved not only by correct deductions from actual conditions and laws, but by observation. This is also recorded geologically by the greater removal of glacial conditions in the northern hemisphere--although in both this removal is yet in progress.

In a globe wrapped in a mass of vapor by reason of evaporation maintained at the surface by its own heat and condensed upon the outer surface of the spheroidal cloud envelope, it is immaterial so far as surface temperatures are concerned, to what degree of outside heat it may be subjected. The only possible effects of variations in the distance from, or intensity of the exterior heat source being to influence the duration of the interior supply and the distance therefrom at which cloud condensation takes place.

In a globe thus enshrouded the same order of surface temperatures would follow, whether revolving in the orbit of Venus or that of Neptune--the actual influences being the greater rate of loss in the remoter position, the more rapid succession of geological climates, and the greater time necessary for the removal of glacial conditions, and for the establishment of solar climatic control. Could the earth have been removed during the Archæan Age to the orbit of Jupiter without disturbing other conditions, no change could have occurred in the order of succeeding geological climates prior to the Ice Age. The rate of receipt of solar energy would have been in the ratio of (5.2)²:1; and the actual retardation of loss would have been in this ratio, as also the rate of establishment of solar climatic control; the crust would have cooled quicker, and therefore have been thinner and less stable than at present.

The observed movements in the cloud envelope of Jupiter present phenomena warranting the belief that his atmosphere is non-transcalent. In this particular it resembles the clouded atmosphere of the earth; and indicates a condition analogous to that of the earth in pre-glacial ages. The smaller planets by reason of their lesser masses have lost their available resident heat. Their atmospheres have become cleared and are both translucent and transcalent. Their surfaces can be observed, and their volumes and densities calculated with a reasonable degree of exactness. In the cases of the larger planets observations are confined to the surface of their spheroidal cloud envelopes, and hence to these planets are ascribed volumes and densities varying abnormally from those whose actual volumes can be measured. The satellites of Jupiter possess much greater densities than that ascribed to the great planet--were it possible to measure the actual volume of his enshrouded mass this apparent anomaly would be in whole or in part removed.

Not knowing the surface temperatures, the exact composition of the atmospheres, nor the dimensions of the planetary masses, the distances to which the cloud envelopes of Jupiter, Saturn, Uranus and Neptune may be expanded, are yet matters of conjecture. Whatever is known of these planets corroborates the interpretation herein rendered of the record of the geological climates of the earth.

THE ESTABLISHMENT OF SOLAR CLIMATES.

At the culmination of the Ice Age the snow line was much lower than at present, and elevated lands at all latitudes were deeply glaciated; the seas were intensely cold. It is evident that since the culmination of the Ice Age and in the establishment of the present climates there has been a great rise in temperatures in the tropical, temperate and sub-frigid zones. There is also indisputable evidence that this rise in temperature is yet in progress. This accession of heat must therefore be accounted for by the correct application of laws and forces now acting, and it is not necessary to go outside of these known laws and forces to render a correct interpretation of the establishment and maintenance of the zones of climate now existing.

It will be observed that when the oceans were exhausted of their heat and the lands deeply glaciated, the crust was shrunk in upon the interior mass by being uniformly chilled down to the lowest temperature to which a planet, upon which water and an atmosphere exist, can be subjected. The atmosphere was then cleared of clouds and heat rays from exterior sources permitted to reach the planetary surface. At once these rays began to be changed into dark heat rays, particularly those from water, and the trapping of heat ensued; from this date a general rise in temperatures must follow from the accession of heat from exterior sources, until checked within the moderate limits hereafter outlined.

The trapping process thus inaugurated is independent of the actual amount of heat received whether from solar or stellar sources.

Were it possible for the now pent-up internal heat to raise the temperature of the oceans, the crust at the bottom of the oceans, and under the polar ice caps to a mean temperature of say 68 degrees Far., the accession of heat from exterior sources would be shut off, as in early Quaternary times, by dense clouds; the exterior would be again shrunk by glacial conditions, the air cleared as before and heat from exterior sources in whatever amounts it then reached the surface would be trapped as succeeded the Ice Age.

This action must in turn take place upon any planet upon which water and an atmosphere resembling ours exist. The rate at which a planet acquires heat from exterior sources is dependent upon the power of its atmosphere to trap heat; very slight variations in the atmospheric constituents producing great variations in heat trapping power.

The trapping process not being a function of the orbital distance, nor of the actual amount of heat received, but of the composition of the atmosphere, this rise, being only a function of the amount received and not of the trapping process, this rise in temperature is as certain to follow in one position as another.

By thus being subjected to the maximum shrinking-strains the weakest portions of the crust were ruptured. The lava ejected from these ruptures was spread out over the weak areas in successive layers of a few dozen feet in thickness until the added strength reached that belonging to thousands of feet of solid rock.

To digress a moment--

These lava overflows evidently performed another important function. The heat set free by each successive layer could not have been lost by radiation into space, for the enshrouding clouds had not yet been removed. The air and clouds caught this heat and bearing it eastwardly in their general course caused warm rains instead of snow to be precipitated upon the adjacent region. In this way the “unglaciated area” escaped glaciation; in this area are the “bad lands” of Dakota, whose topography distinctly shows that sub-aerial denudation, and not glacial ice formed the controlling features. In this area are the great deposits of tertiary fossil life, in perfect form--uncrushed by the mighty tread of the glaciers which surrounded them on all sides, except to the west. From areas such as these went forth the life that survived the glacial winter.

That the isotherm marked by glacial ice is yet slowly retreating upward is recorded not only by tradition and history but geologically and physically, as observed by every scientist who has studied existing glaciers.

This retreat is a positive proof of either a decrease in precipitation on the tributary areas, a rise in temperature, or both of these agencies acting conjointly. There is no evidence to show that a decrease in precipitation is synchronously taking place over the sub-frigid, temperate and tropical regions of both hemispheres, as is the retreat of glaciers; and there are positive and active causes in force which have affected, and are yet affecting an increase in temperature. We must therefore conclude that this rise in the isotherm marking glacial ice is due primarily, if not entirely, to an accession of heat.

It has been demonstrated that at the culmination of the Ice Age, much colder conditions existed than at present. It now remains to explain the conditions acting to bring about existing climates. Upon the exhaustion of the last available remnant of earth heat--left in the oceans by reason of the high specific heat of water--the supply of vapor maintaining the cloud envelope was shut off, and solar heat permitted to reach the planetary surface.