288 Rev. W. D. Com/heave on a Geological Map of [Apr it, 



tions of the Jura chain, where they crop out along the base of its 

 escarpment on the north-west; and an account by Von Buch of 

 the environs of JNeufchatel completes the account by adding the 

 beds in the central and south-eastern regions, where they finally 

 dip beneath the tertiary formations. He divides these forma- 

 tions into four series which he enumerates in a descending order. 

 I have ventured to assign their probable English equivalent, but 

 these can only be considered as mere conjectures at present. 



First Series. 



29 beds of oolites contain madre- 

 pores, 8cc Coral rag. 



Upper marl Oxford clay. 



32 oolitic beds Cornbrash. 



Second marl Clay beneath the cornbrash. 



Second Series. 



486 more compact beds, some of 



which contain strombites Forest marble. 



Third Series. 



350 oolitic beds Great oolite. 



60 beds hard black marl Clay of the fuller's earth. 



Fourth Series. 



100 beds not described, probably 

 the same with those above Lons 

 le saulnier Inferior oolite and lias. 



The Jura chain exhibits arched and contorted stratification 

 through its central ridges ; but on the north-west all the beds 

 crop out, and on the south-east dip rapidly beneath the tertiary 

 formations which occupy the great valley of Svvisserland sepa- 

 rating these ridges from the Alps. The exterior chains of the 

 Alps again exhibit in what have been called the younger varie- 

 ties of alpine limestone, beds of the same age with the above. 



On the south of Geneva, the continuation of the Jura chain 

 unites with these external calcareous chains of the Alps ; and 

 in this vicinity, therefore, the true relations of the several forma- 

 tions ought to be particularly examined. Hence they are con- 

 tinued south through Dauphiny and Provence, but I am not 

 acquainted with any good account of their structure in this 

 quarter. 



(G.) The Alps. 



For an account of these formations in the external chains of 

 the Alps, I refer entirely to the excellent paper of Prof. Buck- 

 land, which has already appeared in the Annals. 



