UPPER SANDSTONES. 227 



-glomerate structure in the lower beds, thus forming _ y , 

 the te millstone grit" of England, but the more pre- 

 vailing textures are fine. They are often exceedingly^ ,_/^z. 

 pure and white, offering the most beautiful of building v -Z^st 

 materials, yet varying much in compactness ; while, in 

 other cases, they are argillaceous, calcareous, or ferru- 

 ginous, presenting corresponding diversities of appear- 

 ance, with many different colours, though red tints are 

 comparatively rare. When impregnated with bitu- 

 minous or carbonaceous matters, they are sometimes 

 black, and they often contain fragments of charcoal 

 or lignite. The very few organic remains found in 

 this series belong almost exclusively to fresh water or 

 to the land ; and the most remarkable are the vege- 

 table fragments, particularly noticed under the history 

 of coal, as the geological relations and characters of 

 this sandstone are necessarily also noticed in the same 

 chapter. 



The next deposit is the Red marl, or the variegated 

 sandstone of foreign writers, also called the New red 

 sandstone, to distinguish it from that described in the 

 former chapter ; while I suppress other synonyms, 

 connected with disputes now useless. This most im- 

 portant deposit claims a far higher rank than the pre- 

 ceding, which, as far as we yet know, is comparatively 

 limited. It follows immediately on the inagnesian 

 limestone, and, in England, is succeeded by the lias 

 and oolithe, though, on the continent, there are inter- 

 posed the muschelkalk and the quadersandstein. 



As a series, it presents a complication resembling 

 that of all the arenaceous and calcareous deposits; 

 including limestones,, clays, marls, and shales. The 

 beds are sometim.es of a conglomerate structure, at 

 others a fine sandstone, and occasionally schistose; 

 and, la composition., die rock Is calcareous, argillaceous, 



