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Published online by Cambridge University Press: 01 May 2009
It has been argued by some that the seas were anciently cooler than at the present day, and that thence certain ulterior effects might be assumed. Without treating of the supposed effects, I wish to state that the premiss itself seems to me inconsistent with what, geologically viewed, appears to be the order of transition through which our planet has passed in its successive changes. My own unprofessional view, founded upon grounds generally admitted, has been that, from a temperature originally much higher, the oceans had gradually cooled down under adequate influences to the mean temperatures which they now maintain under the permanent climatic conditions of the globe; and indeed that the peculiar condition distinguished by geologists as the “Glacial Period” was but the effect of the rapid condensation of the vapours arising during the longcontinued process of cooling, under a great and sudden organic change.
Communicated to Prof. Rupert Jones, F.R.S., in a letter dated December 10th, 1870.
page 352 note 2 I make this remark because I met with a brief notice in the scientific columns of the London Illustrated News of August 13th, 1864, from which I learn that Prof. Frankland, in a then recent lecture, had enunciated views on this subject almost coincident with my own: and also that Prof. De la Rive, of Geneva, had promulgated a similar opinion as far back as 1852. That I feel flattered by the support which my modestly conceived opinion receives incidentally from these high authorities, I need not add; and also that I am thereby rendered the less diffident in its expression.
page 353 note 1 The disturbance here alluded to may be subject to the following explanation. Under an established law of Mechanics the sudden change of the balance of gravitation supposed must necessarily have been attended with a corresponding nutation in the vertical plane, comparatively like the oscillation of a pendulum, or the vibrations of the magnetic needle when accidentally deflected. The first effect hence arising would have been to produce an abnormal declination; in other words, to extend temporarily the limits of the polar zones far beyond their permanent confines: the converse effect, upon reaction, to contract them for a time proportionably, though to a less extent. Hence two extremes of climate, both abnormal, must be conceived to have resulted during an indefinite interval. Successive alternations, each gradually decreasing in intensity, would have followed, until the globe at length subsided under the gravitating force into that state of permanency which it has since retained. The imagination is lost while contemplating either the extent or the duration of the mechanical process thus theoretically assumed. From the vast inertia, however, of the disturbed mass suspended in space and subject to no retarding influence beyond that of gravitating attraction, it seems obvious that the effect must have been both great and long continued: and specially that the extremes of climate, occurring at the reverting points, must have been greatly protracted. This view admitted, it follows that the condensation of the vapours arising from the cooling oceans must have been immeasurably great. A condition of the globe may be conceived of under which, shrouded in mist impenetrable by the solar rays, the formation of snow must incessantly have proceeded. On the contrary, at the opposite point, under a temperature alike extreme, vast floods must have resulted from the melting snows: again succeeded by a reversed condition, producing ice. Thus alternately the process would have continued, each successive revolution lessening in degree, until ultimately the shaken sphere subsided into that normal condition of repose which it has since retained.
The floods thus generated upon the polar confines, in their progress towards the equatorial regions would not. it may be inferred, have assumed a course continuing due south, but deflecting gradually to the westward, in obedience to the same physical law by which the course of the trade-winds is regulated; a result, at least with regard to the Northern Hemisphere, in accordance, I believe, with the course of the ice-drift observed both in Europe and America in those positions where local obstacles have not casually diverted it. By the agency of these floods, in addition to the ice-contained fragments of rocks with the remains of extinct races of animals, the timber, leaves, and other vegetable matter, the produce apparently of the far north in the antecedent condition of the globe, have likewise been transported. These, as shown by the observations of Mr. Charles Whittlesey, are discovered in America imbedded deeply in the diluvial drift.*
page 353 note 2 See Notes on the former existence of the Hippopotamus in Europe, by Mr. Anderson, in the “Reliquiæ Aquitanicæ,” Parts xi. and xii,—Editor.
page 353 note * Prof. Henry's résumé of Mr. Charles Whittlesey's Notes on the Glacial Drift of the North-Western States. Transactions of Smithsonian Institute, 1866, page 35.
page 354 note 1 The analogy between the conditions of the existing Bison of North America and that of the extinct animals is striking; the inference follows in regard to the climatic and seasonal circumstances. Subjected to extremes of heat and cold in its natural habitat, the Bison is endowed by Nature with a provision conformable to both. During winter a thick coating of fine wool underlies its shaggy covering of hair; precisely as in the cases cited in the text. As summer approaches, this wintry garment gradually falls off, and is succeeded by a thin coating of new hair, corresponding for the time with that of the Buffalo of Asia and Africa, to which, as to the modern Elephant and Rhinoceros, a warmer covering is at no time necessary.
page 354 note 2 Upwards of 600 mammoth tusks were last week offered for sale at the Ivory Warehouse, London Docks. Some of these were from nine to ten feet in length, and presented the peculiar double curve so characteristic of the tusks of E. primigenius wherever met with. See Geol. Mag., 1868, Vol. V. p. 540, Plates XXII. and XXIII. —Edit. Geol. Mag.