64? Geological Society, 



But in the neighbourhood of Babbaconribe, he says, there are several 

 faults which at first sight olfe»; p very oiflerent character. Of 

 these he Mentions two, that at Watcombeand another vi^est of Petit 

 Tor rock. The first pre ^ents a vertical cliange of level of about 200 

 feet; but it is not, like the faults bcibi-e a' hi Jed to, rounded off, and 

 therefore the author infers timt ir is of more recent ori-^in. 



Some observations a. e then oflered on ; he position of the trap in 

 the neighbourhood of Babbacombe j and it is shown, t'lat in the hill 

 to the east of ihe town it . ests on sliale, and is overlaid by beds of 

 shale and limestone, tlie fraj) uippir^g to the south-west conformably 

 with the stratified deposits. At its lower suiface it adheres firmly 

 to the shale j but at its upper no such adhesion occurs, though the 

 bed which rests upon the trap is moulded into its outline. From 

 this phaeiornenon, and \\\q. absence of all marks of disturbance, the 

 author infers, that the trap was a submarine lava current, ou which the 

 superincumbent limestone and shale were subs.equently deposited. 

 In other instances, however, as in the hill between Torquay and 

 Tor Abbey, the limestone appears to have been violentl}^ disturbed, 

 the beds of now red sandstone on the flanks of the hill being in a 

 vertical position. 



In conclusion the author oft'ers some remarks on the drainage and 

 destruction of the lake v.^hich he supposes to have occupied the site 

 of the Ballemarsh and Bovey Heathfield. 



A paper, entitled, '< Some Facts in the Geology of the Central and 

 Westei n Portions of North America, collected principally from the 

 statements and unpublished notices of recent travellers," by Henry 

 Darwin Rogers, Esq., F.G.S., was then begun. 



December 3rd. — The reading of Mr. Rogers's paper was resumed 

 and concluded. 



Mr. Rogers states that he is indebted for the greater part of the 

 facts contained in his communication to Mr. Sublette, a gentleman 

 engaged for eleven years in the fur trade; but that he has also ex- 

 tracted from the journals of Long and Lewis, and Gierke and Nutt- 

 hall, such observations as bear upon the structure of the country. 



The district noticed includes the vast tractextendingfrom the Mis- 

 sissippi to the Pacific, and from the S6th to the 49th degree of North 

 latitude. The principal physical features of the country are the 

 Rocky Mountains ; and the immense plains which extend from the 

 Mississippi to that range, circle round its southern termination, and 

 are prolonged into Mexico, and northward to an unknown distance. 



The Rocky Mountains consist, as far as they have been examined, 

 of primary formations, and their eastern chain, the Black Hills, of 

 gneiss and mica slate, greenstone, amygdaloid, and other igneous 

 rocks. Chains of primary mountains, separated by sandy plains and 

 volcanic tracts, constitute the country between the Rocky Mountains 

 and the Pacific ; but to the east of that range are several nearly 

 horizontal formations, of the limits or the^relative age of which lit- 

 tle is known. 



The country from the falls of the Platte to the mountains, and 

 from the Missouri to the Arkansas and the Rio Colorado, as well 

 as the plains included within the Rocky Mountains, is composed of 



