AND STRUCTURE OF THE BELEMNITE. 405 



those contortions and elevations so remarkable at the spots I 

 have enumerated ; and the probable demolition of a large pro- 

 portion of these strata, the remains of which are spread over 

 so great an extent of England, in deposition of loose alluvial 

 gravel. 



The nature of the fluid from which the chalk strata have been 

 deposited, I conceive it an idle pursuit to inquire into ; but 

 that they were deposited from a fluid is admitted on all hands, 

 and that they were deposited, not where they now are, but 

 when deep under the surface of the ocean, is proved beyond a 

 doubt, by the marine remains, and only marine remains, which 

 are peculiar to these strata. No metallic substance has ever 

 been found in chalk, except some iron-pyrites, and that to a 

 very limited extent ; but the organic bodies have been nume- 

 rous, and some of them in the most beautiful state of preser- 

 vation. Difficult and accidental as it must be to extricate such 

 objects, I have sometimes seen a fossil resembling the Echinus 

 circinatus of Gualtieri (whose spines are two or three inches 

 in length) very entire, which denotes that it must have been 

 deposited at a moment when the most perfect quiescence pre- 

 vailed. These appear to me to be legitimate and sound data, 

 on which to ground opinions respecting the nature of the chalk 

 strata, and a more close examination of the fossil remains will 

 perhaps lead to some probable conjectures respecting the for- 

 mation of the flints. 



I conceive it quite unnecessary to enter upon any refutation 

 of Werner's idea, of cavities being left by the expulsion of air, 

 not only from the impossibility of the limestone remaining 

 suspended, as before remarked, but that these very flints some- 

 times contain organic remains entirely enveloped, which could 

 not have been introduced by infiltration, and must have been 

 in the open sea, when the two substances, the siliceous matter 



of 



