Murchisori s Silurian System, 23 



magnesian limestone, and very seldom so much magnesia as 

 to entitle them to the name of dolomitic conglomerate, but 

 are for the most part simply calcareous conglomerates, con- 

 sisting of fragments of quartzy, silurian, and other rocks, as 

 well as of carboniferous and other limestones enveloped in a 

 calcareous matrix. In the Tortworth district, at the northern 

 extremity of the Bristol coal field, the true dolomitic con- 

 glomerate is considerably developed, and has been fully 

 described by several geologists. In the north of Gloucester- 

 shire, and south of Worcester, where 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 calcarious conglomerates which 

 occur at intervals near the bottom of the sandy series, be 

 its representative." 



" In the great expansion, however, of the new red system in 

 the north of Worcestershire, in Staffordshire, and Shropshire, 

 there are calcareous conglomerates of considerable 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 magnesian limestone. They occur 

 in great force in the north-eastern face of the Lickey. 

 See the Memoirs of Mr. Horner, Dr. Bright, Mr. War- 

 burton, Messrs. Buckland and Conybeare, and Mr. Weaver ; 

 Geol. Trans, vol. in. and iv. old series, and vol. i. of new 

 series. This dolomitic conglomerate is also described in this 

 work in the chapter on Tortworth, and the position is mark- 

 ed near the south-eastern extremity of the accompanying 

 map, and Clent hills, and appear also on the northern end 

 of the Lickey ridge of quartz rock, whence they range by 

 Kenelms to Hagley. In this course they distinctly overlie 

 a great formation hereafter to be described as the lower new 

 red sandstone, and rise high on the sides of the trap rocks of 

 the Clent hills. They here vary much in importance, parti- 



