Geological Society of London. 277 



4. " On certain Alluvial Deposits associated with tlie Plymouth 

 Limestone." By E. N. Worth, Esq., JF.G.S. 



The author adduced certain deposits found in fissures and caverns 

 of the Plymouth Limestone, as furnishing evidence in opposition to 

 the views advocated by Mr. Belt in his paper on the Drifts of Devon 

 and Cornwall.' The best examples occur at Plymouth Hoe, where 

 the chief deposit fills a large ''pocket" in the limestone, and con- 

 sists (beneath the turf) of a bed of clayey soil, containing pebbles 

 and small boulders, beneath which are patches of white and red clay, 

 containing a few pebbles, and overlying a large quantity of siliceous 

 sand. Similar, but slightly ^^Brying deposits, not unfrequently occur 

 in association with the Limestone ; and these are regarded by the 

 author as the remains of considerable deposits which once occupied 

 large areas in the valleys of S. Devon ; and if they are not the low- 

 Ian d gravels of Mr. Belt, the latter are not represented in the district. 

 The author states that there is evidence of the contemporaneity of 

 these deposits with those of the Oreston caves ; and he adds that 

 they furnish no proof of cataclysmal action, but of orderly deposition, 

 the bulk of the pebbles and gravels being inland nearer the source of 

 the debris, and further off the sands and clays in fairly regular 

 succession. The author further explains the presence in Cornwall 

 of stanniferous gravels only in valleys opening to the south, by 

 reference to the position of the watershed in that county, which has 

 only two rivers running to ihQ north, whilst on th© south-east rivers 

 abound. 



II.— April 26, 1876. — Prof. P. Martin Duncan, M.B., F.E.S., 

 President, in the Chair. — The following communications were 

 read : — 



1. A Translation of a Notice, by Capt. Miaulis of the Greek Koyal 

 Navy, of the Occurrence of a Submarine Crater within the Harbour 

 of Karavossera, in the Gulf of Arta. Communicated by the Secre- 

 tary of State for Foreign Affairs. 



2. '' The Physical History of the Dee, Wales." By Prof. A. C. 

 Eamsay, LL.D., F.E.S., Y.P.G.S. 



The author stated that he regarded the valley of the Dee as mainly 

 preglacial throughout, and sketched the physical history of the 

 region through which it runs. The Silurian rocks were much dis- 

 turbed and denuded before and during the Carboniferous period, and 

 the Carboniferous Limestone was deposited very unconformably on 

 the upturned edges of both Lower and Upper Silurian strata, and 

 once spread all over the region, probably overlain by the Millstone- 

 grit and Coal-measures, as now in the east of Denbighshire and 

 Flintshire. The region was again disturbed and elevated during 

 the formation of the Permian deposits, and then by subaerial denuda- 

 tion a great part of the Carboniferous series was removed down to 

 the old plain of denudation of the Silurian rocks, the surface of 

 which thus probably stood higher than it does at present, being in 

 the midst of a broad continental area. From a consideration of the 



^ See Quart. Journ, Geol. Soc. vol. xxxii. p. 80. 



