Remarks on the Ancient Flora of' the Earth. 115 



were lately discovered, the division of the old red sandstone and 

 the variegated sandstone is but very imperfect. 



This remark is of still greater consequence, when applied to 

 the distinction of the second and third periods, according to our 

 author's division. In these we observe the variegated sandstone 

 separated from the keuper by the shell-limestone (jnuschelkalk) 

 formation. It is known, however, that there are extensive dis- 

 tricts in which no traces of this rock, the shell-limestone, which 

 separates the two formations, are to be found, and in which the 

 formation of variegated sandstone and the keuper formation are 

 necessarily blended into a single mass. This is the case, for in- 

 stance, in the extensive and important formation of red marl in 

 England, which unquestionably belongs to both formations. It 

 consequently appears to be very difficult, amidst this simple rock 

 formation, to propose a separation of such importance as the ap- 

 pearance of two perfectly new creations of organic beings seems 

 to require. 



Independent of the striking want of agreement known to 

 exist in the division of rock formations, according as they are 

 distinguished, either by the principles of superposition, or ac- 

 cording to the distribution of organic bodies, we would never- 

 theless have attributed no importance to these objections against 

 the method of M. Brongniart. We are further obliged, how- 

 ever, to start various doubts as to the accuracy of some other 

 views presented by M. Brongniart, and closely connected with 

 the principles referred to. 



After the description which M. Brongniart gives us of those 

 relations in which the P'loras of the different formations stand to 

 one another, he proceeds to say, that he is inclined to think that 

 the successive creations of plants are distinguished by a sudden 

 change in the essential characteristics of vegetation. This opi- 

 nion of our author appears to have been formed, as if the inter- 

 vals between the ceasing of an old flora, and the commencement 

 of a new one, had been filled up by an overflowing of the ocean. 

 He has therefore attempted to prove, cither that no organic re- 

 mains occurred, or If any, only diose of marine plants arc found 

 In the strata which separate the members of the four divisions 

 already alluded to. This opinion, however, we are not inclined 



to admit as equally conclusive. 



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