862 On the Classification of the Strata, SfC. [MaY, 



Royal Institution." On that account, he was prevented from 

 referring to Prof. Brande's remarks on the classification of the 

 English formations between the chalk and the red marl (" Jour- 

 nal of Science," No. 39, p. 29 — 31). Any thing proceeding 

 from the pen of the Secretary of the Royal Society is entitled to 

 our attention and respect. But the remarks in question appear 

 rather to have been compiled from the authority of others, than 

 to have been the result of personal observations; and it has 

 been shov^'n above, that in the classification of certain forma- 

 tions below the chalk, our best authorities have been at variance. 

 This may account for some statements, in the paper alluded to, 

 which are not borne out by the natural sections exhibited in 

 different parts of our island. 



At p. 29 (No. 39), the bhie marl, which supports the Under- 

 cliff rock in the Isle of Wight, is identified with the Kimmeridge 

 clay which appears at Shotover Hill, near Oxford. Mr. Smith 

 erroneously identifies the Weald clay and Kimmeridge clay ; 

 Other writers have confounded the blue marl (Cambridge gait) 

 with the Weald clay. It is only by a combination of both these 

 errors that the blue marl and Kimmeridge clay can be con- 

 founded. In point of fact, they are separated from each other 

 by five distinct formations. 



Mr. Brande states (p. 30), that the formations between the 

 iron sand and the chalk " scarcely admit of distinction into 

 strata." The separation of the formations is difficult; but in 

 papers published in the latter part of 1824, in the Annals of 

 Philosophy , the difficulties have been completely overcome. 



In the subsequent paragraph (p. 30, 31), the sands of Woburn 

 and Ryegate are identified with the sands of Tunbridge Wells 

 and Hastings. In the above-mentioned papers, it is demonstrated 

 that this supposition is erroneous. 



At p. 31, it is stated that the iron sand "reaches the north 

 coast of Yorkshire, and covers much of its western district." 

 The whole coal formation, described in the preceding paper, 

 appears to be confounded by the same author with the iron sand. 

 This supposition involves a very great error, and is directly op- 

 posed to the evidence exhibited by the sections on the coast. 



Lastly, in the same page, the alum-shale of Whitby, in York- 

 shire, is identified with the Kimmeridge clay ; an assumption 

 which is entirely inadmissible ; for the two formations bear little 

 resemblance to each other, contain a completely distinct suite of 

 organic remains, and have different geological relations. 



It has been considered necessary to notice the preceding pas- 

 sages in Prof. Brande's " Outlines of Geology," because they 

 were opposed to the conclusions which this paper was intended 

 to establish. 



