104 



THE GEOLOGIST. 



been myself, suggesting, as they do, ideas out of the beaten track. Indeed' 

 from the editorial remarks which have appeared in several of the recent 

 numbers, I perceive that to turn aside from the footprints of the Schools, 

 and to tread in the stranger paths that point towards discovery, is an idio- 

 syncrasy of your mind. 



But my object in addressing you is not to point out that which must be 

 patent to all your readers, but rather to offer some remarks on the ideas 

 which the articles referred to express. My remarks are principally made 

 with reference to the note on " Ancient Climates." 



Before I come to a consideration of your own more immediate views upon 

 the subject, as contained in the latter part of the paper, perhaps I should 

 explain my opinions as regards what you rightly term one of the enigmas 

 of geology — the maintenance on the earth's surface of a high temperature. 



Let us for a moment carry ourselves back in imagination to those early 

 stages of the earth's existence to which science is unable to assign even a 

 probable date, and endeavour to appreciate, in the mind's eye, some of the 

 conditions under which it laboured, when, glowing hot, it was first projected 

 from the anvil of nature into those regions of the illimitable which were 

 destined to be the scene of its career. I say glowing hot, because, although 

 you imply that there is some reason to doubt its ever having suffered any 

 great degree of heat, I for one have never entertained any opinion but 

 that such was its state at one period. 



From the burning, seething mass arises a dark and dense atmosphere, of 

 which carbon and carbonic acid formed the great ingredients, presenting 

 as effectual a screen against the entrance of the sun's rays as it did to the 

 escape of heat from the body of the planet it surrounded. Though the 

 sun occupied its place as the centre, its attributes — light and heat — as far 

 at least as our planet was concerned, were not experienced, " and darkness 

 was upon the face of the deep." 



Gradually the external surface of this cloud-mantle radiated its heat 

 into space — a very slow process, and one that might have taken ages to 

 get rid of five degrees of temperature — and allowed the large overplus of 

 carbonic acid to be deposited in the forms of limestone and mineral coal. 

 The earth was now no longer " without form," but void. 



Let us suppose so long a time to have elapsed that already the fervid 

 body of our globe has cooled down to a comparatively low temperature — 

 the dense mantle that once shrouded her has partially dissipated itself, 

 but a gloomy obscurity still hangs over her, calculated to hold heat in an 

 eminent degree. Water appears next as water, that before formed an ele- 

 ment of the atmosphere only : in short, the waters were divided from the 

 waters. The " firmament," as the early historian describes it, was not 

 the cerulean expanse we are accustomed to see, but one of cloud scenery, 

 through which the struggling sunbeams can with difficulty penetrate earth- 

 wards, obedient to the mandate of the Creator, " Let there be Light." 

 After the appearance of land from out the waters which had been preci- 

 pitated over the entire surface, vegetation made its way ; but was it at all 

 like the vegetation of the present day ? I am inclined to think not. The 

 part in nature that the vegetable world was to play had not been called 

 on ; other scenes were taking place on the great stage from which the cur- 

 tain had but just gone up ; the Deus ex machind of creation had not 

 come on, and the full strength of the company was not yet required. I 

 conceive this early vegetation to have been of a very luxuriant, though, 

 generally, of a fruitless character, making up in mass of leaf and limb what 

 it lacked in flower and fruit. This the large proportion of carbonic still 

 in the atmosphere, and the dampness of the air, together with its high 



