of the Cumbrian Mountains. bll 



the very heart of England, and in a transverse line from the German Ocean 

 to the Irish Sea, and as far west perhaps as the Isle of Man. The remains 

 of the carboniferous strata in the northern and central parts of England, not- 

 withstanding the manner in which they have been dislocated, and afterwards 

 covered up by newer deposits, justify us in giving them this great original ex- 

 tent, and thus bringing them almost to the confines of the carboniferous system 

 of the Bristol Channel. 



This carboniferous period (during which we have no indications of great 

 internal movements producing mountain masses with their strata in discordant 

 positions), was immediately succeeded by some of the most remarkable convul- 

 sions which have affected our island. During these convulsions, took place 

 some of those extraordinary dislocations of the coal measures on the confines 

 of the Bristol Channel (so admirably described in former memoirs read before 

 this Society*), and also the elevation of the great northern central chain, extend- 

 ing from the neighbourhood of Derby to the mouth of the Tweed : and during 

 the same period the calcareous zone surrounding the Cumbrian mountains 

 was torn off from that part of the great northern chain, which, after deflecting 

 a little to the north-west, is prolonged through the crests of Cross Fell to the 

 confines of Scotland. 



I only mention the carboniferous system of the Bristol Channel for the pur- 

 pose of founding upon it one or two general remarks, and of contrasting it 

 with the northern chain of the same period. 



First. The axes of the different coal basins on the Bristol Channel seem 

 to form a striking exception to the rule above quoted, viz., that regions of 

 contemporaneous elevation are marked by parallel lines of bearing. Among 

 the axes of these basins there is certainly no such parallelism. 



Secondly. As the calcareous slates of North Devon and of a part of South 

 Wales do not conform to the rule which appears to govern the range of the 

 greatest number of our greywacke chains; but, on the contrary, run nearly 

 east and west, in a direction parallel to the axis to the great elliptical coal 

 basin of South Wales ; is it not highly probable that the anomaly was caused 

 by the extension to North Devon and a part of South Wales of the same 

 forces which produced the actual configuration of that basin .? Or, in other 

 words, may we not conclude, that the great elevatory movements of the grey- 

 wacke series of North Devon and of a part of South Wales took place after 

 the completion of the carboniferous series; and, therefore, many ages after the 



* See the sections accompanying the Memoir by Messrs. Buckland and Conybeare, Geol. Trans., 

 New Series, vol. i. p. 210, &c. 



VOL IV. — SECOND SERIES. I 



