510 



Scientific Geology. 



first have varied much from a horizontal position : for we know of 

 no examples in which depositions take place in water, where the sur- 

 face is inclined more than a few degrees, except perhaps in those 

 limited cases, where tufaceous masses are deposited from water charg- 

 ed with lime or siiex, flowing down inclined planes. But the older 

 stratified rocks are for the most part highly inclined, often vertical in- 

 deed, as the accompanying Sections will show. They must, there- 

 fore, have been ele\ated subsequently to their deposition. And when 

 we find that a large proportion of the organic remains in the secon- 

 dary rocks are of marine origin, can we doubt that existing continents 

 once formed the bottom of the ocean ? This opinion must now be 

 regarded as an established principle in geology. But by what power 

 was this elevation accomplished 7 That it was volcanic, in the sense 

 in which that term is now generally employed, I very much doubt : 

 because it seems to have acted along extended lines, and not from a 

 center or centers. An hypothesis as to its nature, I shall suggest in 

 another place. But I cannot conceive how the stratified rocks could 

 have been elevated as we find them, without admitting two conditions. 

 First, that the solid crust of the globe must have been comparatively 

 thin, in order to give way to any internal force that we can imagine 

 might act upon it : Secondly, that a molten mass must have existed 

 beneath this crust, so that when it was elevated in any particular part 

 and depressed in others, the fluid nucleus might have readily confor- 

 med to the sinuosities of its inferior surface. Where, for instance, a 

 long mountain ridge was lifted up, if no such fused matter were for- 

 ced up underneath it to occupy the cavity thus produced, it is difficult 

 to conceive how it could be sustained through a lapse of centuries. 

 Nay, it is difficult to conceive how such an enormous weight could 

 have been lifted up thousands of feet, if such a molten mass had not 

 been pressing against it beneath with considerable force, and thus 

 lending assistance to any lateral agency that might have been in ope- 

 ration. Now if granite were not this fused plastic mass, we shall 

 search in vain among the rocks to find one that could have been in 

 such a state : for the trap rocks are not in sufficient quantity to an- 

 swer the conditions of this case ; and they are, moreover,usually asso- 

 ciated with the newer stratified rocks. But granite corresponds both 

 in its nature and position with such a supposition. And if we ex- 

 clude the agency of granite, I do not believe we can account for the 

 elevation of the strata which all admit has taken place. 



2. J infer the igneous origin of granite from the manner in which it 



