444 SKETCH TOWARDS A 



of strata have been independent; regulated by the lands 

 that produced alluvial matters, and the seas that re- 

 ceived them and bore animals. 



Among the primary strata, this is proved by the fact, 

 that in no two parts of the world, are the successions 

 similar: while the correspondence of mineral quality 

 proves nothing, as being the result of the universally 

 influencing cause to which they have been everywhere 

 subjected. Sandstones, shales, and limestones, must 

 have ever been the germs of all strata: and all beyond 

 this is the produce of heat. And the variety of order 

 in the primary strata, now represents a similar variety 

 in those which were once secondary. 



It is not yet known whether or not the old red sand- 

 stone and mountain lime occur all over the world: and 

 till this be ascertained, even the preceding theory may 

 be untrue, as far as it presumes on an universal revo- 

 lution at this period; just as it may be in the case of 

 the coal strata. But it is beyond this that the greater 

 difficulties commence, and the greater assumptions 

 exist. Even in Europe, I have shown that the identity 

 of the upper strata is often conjectural, and often falsely 

 asserted. And Geology, with geological theory, must 

 remain greatly defective, even in the most fundamental 

 facts, until their analogies at least, since I cannot admit 

 of wide identities, shall be traced throughout the world. 

 If here also, therefore, a Theory of the Earth is defec- 

 tive, it is important to point out, as strongly as may be, 

 one of the hypotheses which now especially obstructs 

 its progress. I need not say that my own sketch is, 

 consequently, deficient in this branch of the total theo- 

 ry: yet I have not made the hypothetical division of 

 England a rule for even Europe, however appearing to 

 have done so, and not also presuming beyond this, 

 since I consider the continental deposits which English 



