CHAPTER IV 



NEW RED SYSTEM. 



(continued.) 



3. Calcareous Conglomerate. — 4. Lower New Red Sandstone. 



3. Calcareous Conglomerate. — Equivalents in England : Dolomitic Conglomerate, 

 Magnesian Limestone. — Foreign Equivalent : Zechstein. 



The rocks forming the third division of the New Red System in the central counties, 

 must, from their position, be considered of the same age as the Magnesian Limestone 

 of the North-east, and the Dolomitic Conglomerate of the South-west of England, {d. of 

 wood-cut 5, p. 28.) They do not, however, contain solid beds of magnesian limestone, 

 and very seldom so much magnesia as to entitle them to the name of dolomitic conglo- 

 merate ; but are, for the most part, simply calcareous conglomerates, consisting of frag- 

 ments of quartzy, Silurian, and other rocks, as well as of carboniferous and other lime- 

 stones, enveloped in a calcareous matrix. 



In the Tortworth district, at the northern extremity of the Bristol coal-field, the true 

 dolomitic conglomerate is considerably developed, and has been fully described by 

 several geologists 1 . In the North of Gloucestershire and South of Worcester, where the 

 the New Red Sandstone is conterminous with the Old Red, there are no distinct traces 

 of this member of the series, unless we suppose that the few thin courses of slightly 

 calcareous conglomerate, which occur, at intervals, near the bottom of the sandy series, 

 be its representative. (See p. 51.) 



In the great expansion, however, of the New Red System in the North of Worces- 

 tershire, in Staffordshire, and Shropshire, there are calcareous conglomerates of con- 

 siderable thickness, which, as they pass beneath the great masses of Red Sandstone 

 already described, there can be no hesitation in referring also to the age of the Mag- 

 nesian Limestone. They occur in great force in the north-eastern face of the Lickey 



1 See the memoirs of Mr. Horner, Dr. Bright, Mr. Warburton, Messrs. Buckland and Conybeare, and 

 Mr. Weaver ; Geol. Trans., vol. iii. and iv. Old Series, and vol. i. New Series. This dolomitic conglomerate 

 is also described in this work in the chapter on Tortworth, and the position is marked near the south-eastern 

 extremity of the accompanying map. 



