Ordinary meeting, 3rd February, 1871

149 ORDINARY MEETING, 3rd FEBRUARY, 1871. Th e Rev. T. \VILTBHIRE, M.A., F.G.S., &c., President , in th e Chair. Th e following donations were announced :"Abstract of Proceeding s of the Geologi cal Society," from that Society. " Journal of t he London Insti tu tion," from th at In stitution. " On a New Genus of Graptolites," by John H opkin son, Esq., F .G.S., F.R.M.S., from the Author. The following were elected Members of the Association : Robert Davies Roberts, E sq., and Ernest Swain, E sq. The following paper was read :"On the Geology of the Neighbourhood of Portsmouth and Ryd e." Part II. By OALEB EVANS, E sq., F.G.S. MIDDLE EOCENE.-The lin e of separation between th e L ower and the Middle Eocene is usually drawn. at the t op of the London Olay. All divisions made in a nearly cont inuous series of deposits must be more or less artificial in character, and it may be questi oned whether a mor e natural subdivision would not be made if the bed of sand next to be noticed, and generally kn own as th e Lower Bagshot Sand, were includ ed in the Lower E ocene division, and the separation were made at th e thick deposit of rounded pebbles which follows. The recurr ence of beds of pebbles at intervals is a very conspicuous feature in th e Hampshire Tertiaries and is one of considerable importance, since the increased transporting power, which the presence of th ese pebbles denotes, probably resulted from importan t changes in t he physical geography of the area over which they were dispersed. The whole of the period during which th e Lower and Middle E ocene st rat a were deposited appears to have been one or" g radual depression, which t ook place in general at a rate so slow that it was neutralised by the deposit of sediment, since throughout a thickness of more than 1500 feet shells characteristic of shallow water prevail, and at several levels occupy the position in which they lived. At intervals more rapid depre ssions appear to have taken place, r esulting in the removal of