474 ON THE SUCCESSIVE FORMS 



far greater than that of the first consecutive portion 

 of the secondary, so the duration of that state of the 

 earth which preceded the one in which the present 

 primary rocks formed the only surface, was greater 

 than the duration of that which immediately followed 

 it, and of which the length is measured by the first 

 portion of the secondary strata. The primary 

 strata measure the repose of the preceding ocean. 



Beyond this w 7 e cannot go a step on the subject of 

 duration; at every point anterior to it, all must for 

 ever remain unknown, because we have no longer any 

 deposits of strata by which to calculate. Changes 

 have been proved; and, with these, our enquiries must 

 inevitably cease. Here also I must terminate the 

 history of those states of the earth which bring us 

 down to the secondary strata; to that which has been 

 supposed the last great revolution of the earth, but 

 which, I hope to show, is only one out of many, of 

 which the traces are legibly written in characters that 

 cannot be misapprehended. 



On the Revolutions concerned in the Secondary Strata. 



While the present primary rocks formed the sole 

 dry land of the terraqueous globe last described, the 

 usual causes of waste were depositing on the bottom 

 of its ocean, materials destined to rise again in future 

 strata. As the former had been already displaced, 

 the horizontal deposits which thus covered them 

 became necessarily inconsecutive ; preserving, how- 

 ever, a parallelism in some places, while they assu- 

 med, in others, one variously reverse, according to the 

 previous state of the foundation on which they were 

 laid. In that various position, we now find them 

 elevated above the surface of the water; arid thus the 

 secondary strata, or that division of them now under 



