Supplement to Mr. Sedgwick's Paper on the Magnesian Limestone. 



Some parts of the preceding- paper on the Magnesian Limestone have been 

 written nearly seven years ; and the whole of it was drawn up in the year 

 182G very nearly in the form in which it is now printed. The subsequent 

 discoveries of foreign geologists, and my ov/n recent examination of some of 

 the secondary deposits of the Continent, induce me, during- the passage of this 

 volume through the press, to add the following- supplementary remarks. 



The comparison of the magnesian limestone with some of the great cal- 

 careous formations of the Alps* I now consider erroneous. 



The two vegetable impressions found in the marl-slate were far too im- 

 perfect to be identified, but were supposed to be derived from ferns') . This 

 opinion may admit of doubt, especially since the discoveries of M. VoUz, who 

 has found new tribes of plants {Conijcrce, &c.) in the formation immediately 

 superior to the magnesian limestone. 



The positive identification of the inferior red sandstone with the g-res des 

 Vosges may also admit of doubt;];. The two formations in some of their 

 mineral characters closely resemble each other, and they are very nearly in 

 the same jiart of the secondary series. As, however, the eminent geologists 

 of the Contiiient are not entirely agreed as to the exact place of the gres des 

 Vosg-es, it is perhaps premature to refer to that formation in the general com- 

 parisons of this paper. 



After a personal examination of the secondary formations on the flanks of 

 the Hartz mountains, 1 see no reason to change any part of the comparison 1 

 have made between the contemporaneous formations of England and of central 

 Germany §. The inferior red sandstone is perfectly identical with the rothe- 

 todte-liegende of Mansfeld. I may however remark, that the term rothe-todte- 

 liegende has been used very vaguely, and that, in the neighbourhood of Halle, 

 it is still applied to two systems of red sandstone and conglomerate, which are 

 separated from each other by the coal formation. To the fine development of 

 the hunter sandstein, muschel-kalk, and keuper, and to the great suites of 

 characteristic fossils which are found in each of them, the English strata un- 

 fortunately offer very few parallels. But in a general way, the red sandstone 



* p. .39. t p. 77. t p. 75. § p. 121, &c. 



