OF THE EARTH. 483 



of the surface, apparently the reverse of all the pre- 

 ceding ; consisting in a depression of the land, instead 

 of its elevation. Thus depressed, the ocean which 

 covered the coal strata and all those which sank with 

 it, became the repository of the materials for the next 

 consecutive series of the secondary strata ; commencing, 

 as we suppose, with the magnesian limestone, and 

 terminating at a point which does not appear to have 

 been the same in every part of the world. In England, 

 it is the chalk. 



The effects of this change, viewed as a revolution, 

 must have been no less extraordinary than its cha- 

 racter; since it implies a corresponding depression, 

 not only of the secondary strata beneath, but of the 

 primary rocks also, with a change in the disposition 

 of the earth, wherever it occurred, extending to great 

 depths and of enormous magnitude. Such views as 

 this may be alarming to minds which fear to move 

 one step out of the mere path of observation; yet 

 every part of the theory of the earth, thus far, is so 

 mutually linked, and every fact so confirms every other, 

 that we cannot stop in the chain of consequences. 

 They who will not reason may renounce the whole, 

 but they cannot except a part. 



With respect to the probable extent of this revo- 

 lution, the decision must rest on that of the Coal 

 strata throughout the globe, and the accuracy with 

 which they have been ascertained. The extent is 

 sufficiently considerable to prove a very general re- 

 volution of this nature: but until it is ascertained 

 that all these deposits correspond in geological po- 

 sition to those under review, we must remain un- 

 certain. Many appear, as some are proved to be, of 

 this nature: and even these may suffice to establish a 

 wide revolution of this kind, while future observations 



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