Geological Survey of the Island of Jersey. 373 



of this stone. The Minquiers and remaining islets (on good 

 authority) are composed of the same rock. 



The want of leisure prevented my examining the rocks of 

 Chauzey with the same minuteness as those of Jersey ; and on 

 the French coast, being still more limited, I was obliged to 

 relinquish the second geological object, actual boundaries and 

 extent, and confine myself almost exclusively to the primary 

 one, order, as 1 found them between Coutances and Mount 

 St. Michael. 



Coutances itself stands on a slate hill, strata dipping south : 

 proceeding south, and crossing the Soulle, you still find slate, 

 but overlaid at the foot of the hill by quartz, pebbles, and a 

 conglomerate (63) of red sandstone, in a matrix of the latter 

 dipping west, and capped by a diluvial deposit of the same. 

 One mile and a half on the direct road to Avranches, brings 

 you to a species of siliceous oolite, of which the specimen 

 64 shews the largest grained sort that 1 could find ; there 

 was a finer kind very closely resembling, in texture, the regu- 

 lar calcareous oolite : in fact, a variety of sandstone. The 

 broad top of the first hill, south of Coutances, is a heath, under 

 the surface of which, to the depth of a few feet, debris of 64, 

 imbedded in 67, lie on the parent rock, which, on the Granville 

 road, and on the same hill, becomes 65, intermixed with 62, 

 and alternating with it 67, and 68, dipping north. Still fol- 

 lowing the Granville road, at the foot of the above-mentioned 

 hill, this red sandstone proves itself to be the old red sand- 

 stone by overlying limestone, 69. which, from its madreporites, 

 (these I found in a large polished slab from Mount Martin) 

 corresponds to the transition limestone at Plymouth. According 

 to the geological map, in Coneybeare and Phillips, this rock, 

 in Devonshire and North Wales, is found in long stripes, and 

 it maintains the same character here ; lying east and west, 

 extending (according to the best information I could collect) 

 a few leagues only inwards, and not exceeding two miles in 

 breadth : 66, is obtained two leagues west of Coutances ; 1 

 had not time to visit the spot. 



At Hienville, this limestone is underlaid by another red 

 sandstone, dipping east. Where this overlies the slate I can- 

 not say, as the hill recedes from the road, which, further on, 



