250 Elie de Beaumont's Researches on some of 



The elevation of the chain of the North of England has 

 very probably not been an isolated phaenomenon. If we glance 

 at the geological map of England by Mr. Greenough, and 

 that which accompanies the memoir of Dr. Buckland and 

 Mr. Conybeare on the environs of Bristol, we are naturally 

 led to remark that the problematical rocks which pierce and 

 dislocate the coal deposits of Slirewsbury and Colebrooke 

 Dale, and those which constitute the Malvern Hills, appear 

 connected with a series of fractures which run nearly north 

 and south, being prolonged across the recent transition beds 

 and the carboniferous rocks to the environs of Bristol. 



The coast, with a north and south direction, which bounds 

 the western part of the department of La Manche, may pro- 

 bably also be due to a fracture of the same class as those of 

 the great carboniferous chain of the North of England. 



IV. System of the Pays Bas and of South Wales. — From the 

 environs of Aix-la-Chapelle to the small isles of St. Bride's 

 Bay, Pembrokeshire, over a length of about four hundred 

 English miles, the different portions of the carboniferous series, 

 wherever they are not concealed from observation by more 

 recent formations, are seen in a greater or less state of com- 

 plete dislocation. There are situations, as at Liege, Mons, 

 Valenciennes, the Boulognais, and the Mendip Hills, where 

 they have suffered very considerable contortions and disloca- 

 tions. Throughout a large portion of this extent, these beds, 

 which in no part rise to great heights, are covered by more 

 recent deposits, resting horizontally on their edges. The vast 

 sheet of recent deposits which covers the carboniferous series 

 between the environs of Boulogne and those of Bristol, might 

 even throw doubt on the mutual connection of the dislocations 

 in the Pays Bas and the coasts of the Bristol Channel : it is 

 nevertheless certain that the dislocations in both situations 

 possess common characters ; such as not widely differing from 

 an east and west direction, without however preserving the 

 same line of bearing for great distances, and only producing 

 small protuberances on the surface of the land, notwithstand- 

 ing the contortions of the beds in the interior. 



In the environs of Liege and Aix-la-Chapelle, the direction 

 of the carboniferous beds becomes nearly parallel to that of 

 the argillaceous slates and grauwacke of the Eiffel and the 

 Hundsruck ; but it is probable that this arises from the frac- 

 tures of the carboniferous series having been inflected in such 

 a manner as to follow the ancient dislocations of the pre- 

 existing rocks; for it would be difficult not to admit, from the 

 facts previously noticed, that the elevation of the slate and grau- 

 wacke of the Eiffel and the Hundsruck, following a direction 



nearly 



