410 



THE GEOLOGIST. 



most gigantic mountains in the world — the Himalaya. One can un- 

 derstand a rugged mountainous tract being uplifted, self-uplifting 

 by expansion, by crystallization ; but one cannot understand a moun- 

 tain being permanently upheld on a gaseous explosion, or buoyed up 

 by a generation of steam at high pressure. All such theories pre- 

 suppose mighty caverns in the interior of the earth's crust, or the 

 earth itself, for the generation of such steam or gases; and after 

 that these have expended their energy, are we to suppose that the 

 tract upraised reposes on nothingness ? Is it not worth studying to 

 find out what effects the crystallization of vast rock-masses are capable 

 of producing ? 



NOTES RESPECTING THE OBIGIN OE THE WOBLD. 

 By Thomas Harbison, or Melbourne. 



The tyro in geology usually experiences no small difficulty in reali- 

 zing the present theory of the world's formation. The various sedi- 

 mentary rocks are of such vast thickness, that the question is very 

 naturally put, as to where such an immense amount of detritus 

 could possibly have been originated ; and although not exactly so 

 taught in elementary works, there are few students of geological 

 science who do not come to regard granite as being not only the 

 foundation of the globe, but also the grand storehouse whence, in the 

 shape of water- worn and eroded fragments, has been obtained the 

 whole mass of the purely aqueous strata. 



With the above questions come yet others : Whether there is a pos- 

 sibility so hard a material could be so completely broken up as to form 

 clay-slates, mud-stones, and others of almost impalpable grain and tex- 

 ture ? Whether there is good ground for supposing lime, magnesia, 

 alumina, and iron are found sufficiently plentiful in any species of 

 granite to have given rise to the extensive deposits of such minerals 

 found in particular formations ? and also, how it is that various rocks, 

 all proceeding from the parent granite, should differ from each other 

 in their component parts so materially, merely as such rocks have 

 been the product of different geologic ages ? 



The first of these questions is generally referred to almost an in- 

 finity of time, during which the erosive action has been going forward ; 

 whilst sorting of materials, chemical changes, and the influences of 

 organisms, in the shape of plants and animals, are put forward as 

 afRrrding satisfactory explanations of the two following difficulties. 



The case, however, even admitting the correctness of the preceding 

 propositions, can hardly be regarded as clearly proven. The respec- 

 tive thicknesses of the three different formations — primary, secondary, 

 and tertiary, are in the very inverse order of what might be expected 



