THE PRE-ADAMITE EAKTH. 



Such is a brief and rapid sketch of the phenomena which 

 form the subject of the pre- Adamite history of the globe, which 

 it is our present purpose briefly to sketch. 



196. The manner in which the geological age of mountain- 

 ranges is determined by the state of the strata observed upon their 

 slopes has been already explained, but this is so important an 

 element in our present inquiry, that it may be useful to 

 recapitulate it and present it to our readers under another 

 aspect. 



When we see anywhere the sedimentary strata composing the 

 crust of the earth inclined, we can pronounce with certainty that 

 they have been disturbed from their original position which was 

 horizontal, and that, in short, an elevation has taken place by a 

 force acting from beneath. So far as relates to the strata thus 

 inclined, the epoch of the catastrophes would be undetermined, but 

 if at the foot of the mountains we find other strata a 6 c, fig. 112, 



Fig. 112. Fig. 113. 



horizontal, it becomes evident that the elevation of the former 

 must have taken place before the deposition of the lowest of the 

 latter, since the latter are in the position in which they 

 naturally subsided from the waters. 



The geological date of the elevation in this case would be between 

 the period of the strata, which are elevated and inclined, and the 

 lowest, a, of the horizontal strata. In the case of all mountain- 

 ranges, data of this kind, determining the geological epochs of the 

 disruption which produced them, are supplied. In some places 

 we see for example the stratum a, heaved upwards, and b 

 horizontal, fig. 113. In such cases the date of the catastrophe is 

 posterior to the deposition of a, and anterior to that of b. 



Fig. 114. Fig. 115. 



In other cases, both a and b, fig. 114, are uplifted and inclined,, 

 but c is horizontal, and it is accordingly inferred, that the date 

 6 



