96 Prof. Sedgwick and Mr. Murchisoti on the 



South-west of Schwatz this system terminates in red conglo- 

 merates, and is seen distinctly to rise up to, and repose upon, 

 the older formations. 



In this part of the range the limestone greatly predomi- 

 nates in the exposed sections ; for the red marls and sand- 

 stones being more destructible, do not form precipices, but 

 occupy small longitudinal valleys. The contortions of some 

 of the limestone beds, and the nature of their alternations with 

 the sandstone, are well exposed in sections south of Ratters- 

 berg. We believe that the greatest number of these limestone 

 beds are magnesian, some of them are metalliferous, and nearly 

 all of them are fetid*. Their structure is extremely various. 

 Some of them are compact, some white and crystalline, some 

 yellow and earthy, and some cavernous. When struck with 

 the hammer, some of the masses shiver into innumerable frag- 

 ments; and one of these varieties, of a beautiful white colour, 

 has externally the small columnar structure of dried starch, and 

 when struck falls into minute grains with trapezoidal faces. 

 The name of rogenstcin has been given to this variety, which 

 however presents no analogies to the rogenstein of the Hartz. 



This limestone series has often been called transition. We 

 have allowed the difficulty of drawing a line between the se- 

 condary and transition systems of the Alps ; and in this in- 

 stance we derive no assistance from organic remains, for a few 

 casts of Terebratulae are the only fossils we saw in the beds 

 we are describing. They are, however, too much interlaced 

 with the lower part of the red sandstone to be separated from 

 it; we agree therefore with Dr. Buckland in considering them 

 secondary : and if the red sandstone of the Alps be identi- 

 fied with the new red sandstone, they approach both in posi- 

 tion and in mineral character, much nearer to the zechstein or 

 magnesian limestone than to any other formation with which 

 we are acquainted. At the same time we wish carefully to 

 distinguish them from the great zone of older Alpine lime- 

 stone, from which they are separated by the red sandstone and 

 gypseous marls, and to which, according to our views, they are 

 in no respect subordinate. 



4. Older Alpine Limestone. 



By the term Alpine limestone we mean the limestone found 

 in any part of the great secondary calcareous zones superior 



angle with the range of the red sandstone system, and therefore conveys 

 an erroneous idea of its thickness ; which, however, after every deduction, 

 must be very considerable. 



* Most of the old works below Schwatz were, we believe, in veins of 

 argentiferous galena. They are now deserted. 



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