Geology. — On the Crust of the Earth. 295 



rived their origin from the interior and unsearchable parts of 

 the globe. 



To some who have never reflected upon this subject, it may 

 appear startling to hear, that continents and chains of mountains 

 have been raised from the interior parts of the earth by the force 

 of subterranean expansive power; but every effect is propor- 

 tionate to its cause, and where the first is definite and the last 

 immeasurable, we must submit to the reasonableness of the pro- 

 position, remembering always, that although human power 

 dwindles into insignificance, when applied in imagination to dis- 

 turb a mineral mass like the crust of the earth, which has a 

 thickness of between seven and eight miles attributed to it ; yet 

 that the semi-diameter of the earth exceeds more than five hun- 

 dred times the space occupied by that crust ; and that it is de- 

 monstrable that a gaseous pressure may be generated in such a 

 radius, to which the known mineral mass could make no resist- 

 ance. In reasoning therefore upon these high matters, we must 

 not measure unknown forces by our own feeble powers, but by 

 the effects they are capable of producing, and must treat of the 

 causes and of the effects of this high planetary character, in 

 relation to the proportion in which they stand to each other. 



Mr. De la Beche, in his Sections and Views illustrative of geo- 

 logical phenomena, has an admirable Plate on this subject, which 

 will do much towards reconciling the most incredulous to the 

 views we have offered. We have made this plate somewhat 

 more elementary, in accordance with our plan. *A. Fig. 1, 

 is the radius of the earth, from which at B. a line is set off at 

 100 miles from the level of the sea. A. Fig. 2. represents the 

 same radius multiplied 10 times. B. is a line at 100 miles 

 from the level of the sea. C. a line eight miles from the tops of 

 the highest mountains. D. the level of the sea. E. the height 

 of the Himalaya and Andes. F. the Alps. 



The crust of the earth has been often likened to the propor- 

 tion which the varnish on a cabinet globe bears to the mass it 

 encloses, but this Diagram appeals more strongly to the imagi- 

 nation. It is evident that the pneumatic forces which may be 

 generated in this radius, are capable of producing inequalitica 

 upon the earth's surface, that would, to use the language of 

 Shakspeare, " make Ossa like a wart," even if they had their 



• Vide PI. 8. 



