Geological Society of London. 183 



tinental permanence based on such regions was worthless. He also 

 showed that both elevations and depressions exceeding 1000 fathoms 

 had taken place in Tertiary times, and gave an account of the biolo- 

 gical and geological facts in support of a former union between 

 several lands now isolated, and especially between Africa and India 

 via Madagascar, and between Africa and South America. From 

 these and other considerations it was concluded that the theory of 

 the permanence of ocean-basins, though probable, was not proved, 

 and was certainly untenable to the extent to which it was accepted 

 by some authors. 



The Ballot for the Council and Officers was taken, and the following were duly 

 elected for the ensuing year : — President: A. Geikie, LL.D., F. R.S. Vice-Presi- 

 dents: Prof. T. G. Bonney. D.Sc, LL.D , F.R.S. ; L. Fletcher, Esq., M.A., F.R.S. ; 

 W. H. Hudleston. Esq., M.A., F.R.S.; J. VV. Hulke, Esq., F.R.S. Secretaries : H. 

 Hicks, M.D.. F.R.S.; J. E. Marr, Esq.. M.A. Foreign Secretary: Sir Warington 

 W. Smyth, M. A., F.R.S. Treasurer : Prof. T. Wiltshire, M.A. , F.L.S. Council: 

 Prof. J. F. Blake, M.A. ; W. T. Blanford, LL.D.. F.R.S.; Prof. T. G. Bonney, 

 D.Sc, LL.D.. F.R.S.; James Carter. Esq.; John Evans, D.C.L., LL.D.. F.R.S.; 

 L. Fletcher. Esq., M.A., F.R.S.; A. Geikie. LL.D., F.R.S.; Prof. A. H. Green, 

 M.A., F.R.S.; A. Harker, Esq., M.A. ; H. Hicks, M.D., F.R.S.; Rev. 1 Edwin Hill 

 M.A.; W. H. Hudleston, Esq., M.A., F.R.S.; J. W. Hulke, Esq., F.R.S.; Major- 

 Gen. C. A. McMahon; J. E. Marr, Esq.. M.A. ; H. W. Monckton, Esq.; E. T. 

 Newton, Esq.; F. W. Rudler, Esq.; Sir Warington W. Smyth, M.A., F.R.S.; W. 

 Topley, Esq., F.R.S.; Rev. G. F. Whidborne, M.A. ; Prof. T. Wiltshire, M.A., 

 F.L.S. ; H. Woodward, LL.D.. F.R.S. 



II. — February 26, 1890. — J. W. Hulke, Esq., F.R.S., Vice- 

 President, in the Chair. — The following communication was read: — 



" On the Relation of the Westleton Beds or ' Pebbly Sands ' of 

 Suffolk to those of Norfolk, and on their Extension inland, with some 

 Observations on the Period of the Final Elevation and Denudation of 

 the Weald and of the Thames Valley." — Part III. On a Southern 

 Drift in the Valley of the Thames, with Observations on the Final 

 Elevation and Initial Subaerial Denudation of the Weald, and on 

 the Genesis of the Thames." By Prof. Joseph Prestwich, D.C.L., 

 F.R.S., etc. 



In this third part of his paper the author gave a description of 

 the character of the Southern Drift, showing how it differs from the 

 Westleton Beds in the nature of its included pebbles, which consist 

 of flints from the Chalk with a large proportion of chert and rag stone 

 from the Lower Greensand, while there is a total absence of the 

 Triassic pebbles and Jurassic debris characterizing the Northern 

 Drift. He traced the drift through Kent, Surrey, Berkshire, and 

 Hampshire, and described its mode of occurrence. 



Another preglacial gravel was then discussed under the title of the 

 Brentwood group, and its age was admitted to be doubtful. 



The author then entered into an inquiry as to the early physio- 

 graphical conditions of the Wealden area, and gave reasons for 

 supposing that a hill-range of some importance was formed in the 

 Pliocene period after the deposition of the Diestian beds. From the 

 denudation of this ridge, he supposes that the material was furnished 

 for the formation of the Southern Drift, which may have been de- 

 posited partly as detrital fans at the northern base of the range. 



The relation of the Southern Drift to the Westleton Shingle and 



