Miirchison's Silurian System. 25 



it would be impracticable to define with precision their limits, 

 since they graduate into, and form a part of the lower red 

 sandstone, which in its turn overlies and passes into the coal 

 measures. It will indeed be shown in the sequel, that other 

 calcareous beds, for the most part, however, of true concre- 

 tionary structure, are even traceable down into the coal 

 measures ; and for this reason, I restrict the comparison with 

 the magnesian limestone, or dolomitic conglomerate, to the 

 mass of this rock which immediately lies beneath the central 

 sandstones," (Bunter sandstein, or Gres bigarre.) 



" Calcareous conglomerates are to be seen at many points 

 round the outlineof the Dudley and Wolverhampton coal-fields, 

 generally at some little distance from the edge of the coal-bear- 

 ing strata, and always dipping away from, or overlying them." 



It is impossible in a work composed almost entirely of 

 important details, on which the principles of geological 

 science so much depend, to offer any abstract or comments 

 half so instructive as simple quotations from the observations 

 of the author, especially as sandstones and rocks of the coal 

 formation prevail very extensively in nearly all parts of India. 

 It is extremely important, that the relative position of the 

 sandstones and coal-bearing strata of India should be clearly 

 described, and that all the points in which they differ from, 

 or agree with, similar rocks in other parts of the world, 

 should be investigated. In a private letter from our friend 

 Mr. Jameson, we learn that he has observed extensive tracts 

 composed of silurian rocks, and sandstone of the Old Red 

 System, in the north-western parts of India. Under these 

 circumstances, we feel assured that we can render no better 

 service than by quoting largely from the pages of a work, 

 which otherwise would, from its price, be little known in India. 



The calcareous strata of the New Red System at Coton, 

 where they are burned for lime, are described as coarse con- 

 glomerate, composed chiefly of fragments of carboniferous 



E 



