Tossil Fish of Seefdd, in the Tyrol. 39 



Sedgwick and myself*, with which it further coincides in con- 

 taining no animal remains, except fish ; and as copper ore is 

 extracted from this same chain of dolomite a few miles to the 

 west, I am on that account still more inclined to refer this 

 schistose deposit to some one of the formations between the 

 new and old red sandstone, so remarkable for their abundance 

 of Ichthyolites afnd their metalliferous character, among 

 which the Thuringian copper slate, the magnesian limestone 

 of England, and the Caithness schist, constitute prominent 

 groups of different ages. Chemical analysis of the schist kindly 

 undertaken b}' Mr. Faraday indicates, that it contains a much 

 larger proportion of ammonia than has ever been obtained, 

 from any quality of coal, however bituminous ; and although 

 no positive conclusions can be drawn from this circumstance, 

 still, when the vast number of the fossil fish is considered, a 

 strong suspicion may be entertained that the destruction of 

 such animal matter may have cooperated in the bituminiza- 

 tion of the stone. The schist in its upper portion passes into 

 a compact yellow dolomite which rises into rugged and barren 

 peaks, the forests of pine wood terminating with the superior 

 limit of the bituminous beds. — And here I cannot but express 

 my dissent from that theory of Von Buch by which he attempts 

 to account for the origin of all the dolomite of the Tyrol, of 

 whatever age it may be. That eminent geologist imagines that 

 these vast and lofty mountains acquired their dolomitic cha- 

 racter by the magnesia derived from augitic rocks in a state of 

 fusion. Now although in some localities which he cites, and 

 where pyroxenic rocks are either in contact or contiguous with 

 the dolomite, (as in the valleys of Fiemme and Fassa,) it may 

 be allowed that secondary limestones have been altered into 

 crystalline marble, and occasionally thrown up into fantastic 

 forms ; theie is no possibility of a similar cause having pro- 

 duced the dolomite of Seefeld, where there is not a vestige of 

 any igneous rock in the neighbourhood, but, on the contrary, 

 where strong beds of the dolomite alternate regularly with the 

 bituminous schist containing fossil fish. No geologist has ever 

 sought to explain the presence of magnesia in the great de- 

 posits which are so highly charged with it in England and in 

 Germany, by any theory like that of Von Buch ; and if it be 

 conceded that magnesia may have been an original ingredient 

 in one formation, we may equally presume that it was an ori- 

 ginal ingredient of any other in which we now find it. For we 

 know that tlie mountain limestone in England, the oolitic series 



* In a memoir of tlic (brlhcominn; Part of the rjcolopicarrransactions, 

 now in the press ; and rciiii before tiic Geological Socicly, June 1828. 



in 



