214 Rev. W. D.Conybeare on a Geological Map of [March, 



bling the rauchwacke or cellular limestone of the Continent, 

 associated with magnesian limestone. 



In the southern counties, these formations are represented by 

 a calcareo-magnesian conglomerate, occasionally, but very 

 rarely, passing into limestone beds of uniform texture. These 

 conglomerates bear a great analogy, as Mr. Weaver has well 

 remarked to the weissliegende of Germany. 



These formations must be considered as parallel to, rather 

 than identical with, the alpine limestones of the Continent. 



The above deposits are comparatively very limited in England, 

 and nine-tenths of the tract occupied by the great series we are 

 now describing, is exclusively possessed by the superincumbent 

 variegated sandstone and marl. 



Salt or salt springs occur in Cheshire, Staffordshire, and 

 Worcestershire ; gypsum, passim, and sulphate of strontian, in 

 Gloucester and Somersetshire. 



(C.) Western France. 



The new red sandstone which crosses the channel from 

 Devonshire, is seen, though not extensively, skirting the transi- 

 tion rocks of Brittany ; but the lias and oolite advance so near 

 to them, as almost to overlie and conceal it ; as also seems to be 

 the case in the centre of that country, against the northern edge 

 of that great group of primitive ridges branching off from the 

 Cevennes ; but we want information on this district. 



According to the interesting communications of Dr. Boue, the 

 variegated sandstone exists in patches (par lambeaux) in the 

 south-west of France. It is there represented by marls with 

 compact and fibrous gypsum (Cognar St. Froult, near Rochefort), 

 and sometimes immediately covered by Jura limestone, &c. At 

 the foot of the Pyrenees between St. Giron and Rimont, it is 

 more extensively developed. 



(D.) Spain. 



Humboldt is of opinion that the limestone of Montperdur is 

 that belonging to the present series. The specimens I have 

 seen, and the fossils described as occurring in it, would certainly 

 induce me to assign it to a later era (namely, that corresponding 

 to our green sand), since it much resembles those rocks in the 

 exterior chains of the Alps which are, by Messrs. Buckland and 

 Brogniart, referred to that class ; but I can hardly bring myself 

 on such slight data even to suggest an inquiry militating against 

 so high an authority. Be this as it may, after crossing the 

 Pyrenees, the rock salt of this formation occurs associated as usual 

 with gypsum at Cardona (a description of which will be found 

 in the fourth volume of the Geological Transactions). The 

 celebrated conglomerate mountain of Montserrat in the same 

 quarter, is, perhaps, referable to the same era ; and we find 

 gypsum and rock salt abundantly distributed along the course of 



