Reports & Proceedings — Geological Society of London. 327 



of the first Prestwich Medal. The President added that he felt sure 

 that the Fellows would associate themselves with the resolution of 

 condolence and sympathy which the Council had addressed to 

 Lady Avebury. 



The following communications were read : — 



1. " On the Age of the Suffolk Valleys ; with Notes on the Buried 

 Channels of Drift." By Percy G. H. Boswell, B.Sc, F.G.S. 



The main watershed of Suffolk follows generally the Chalk 

 escarpment, but keeps rather to the east of it, running in a north- 

 easterly direction from Haverhill in the extreme south-west of the 

 county. Suffolk forms a plateau, 100 to 400 feet O.D., dissected by 

 a valley-system which is palmate in form; the chief rivers, taken from 

 north to south, being the Waveney, tlie Aide, the Deben, the Gipping 

 (with its estuary, the Orwell), the Brett, and the Stour. The Little 

 Ouse and the Lark flow north-westwards into the "Wash basin. 



The strata (Challc, Lower London Tertiaries, London Clay, Crags, 

 etc.) cut through by the valleys, and the mantle of glacial deposits 

 (sands, gravels, and loams, Upper Boulder-clay, and morainic gravels), 

 which more or less covers the whole county, are desei'ibed briefly. 

 Reasons are given for thinking that the Contorted Diift does not 

 extend far south of the Waveney. The valleys, although they may 

 have been etched earlier, are on direct evidence post-Pliocene in age ; 

 but, by analogy witli the Waveney and the Norfolk rivers, they may 

 be younger than the Contorted Drift. 



The Upper Boulder-clay (=the Great Chalky Boulder-clay of 

 S. y. Wood, jun.) covers much of the plateau, and wraps down into 

 the valleys in a very characteristic manner. The glacial Sands, etc., 

 below it also appear at times to lie on the valley-slopes. Intense 

 glacial disturbances are found to be situated always on 'bluffs' or 

 'spurs' of the plateau projecting into the wide open valleys, which 

 were thus in existence before the advent of the valley glaciers to the 

 action of which the disturbances have been attributed. 



In each of the main valleys occur one or more buried channels 

 of Drift ; borings made recently allow these to be described in detail, 

 and the deposits filling? them to be discussed. A contour map of the 

 top of the Chalk is prepared for the county, and this serves to bring 

 out the anomalies in the valleys. These buried channels were 

 probably eroded by sub-glacial water-streams, and a comparison is 

 instituted between them and the Fohrden of North Germany, 

 Schleswig-Holstein, Kerguelen, etc., described in detail by Dr. Werth 

 and others. 



The evidence, therefore, indicates that the pre-Glacial or early 

 Glacial contours of Suffolk were in the main much as they are now. 

 The form of the rivers and valleys suggests that some amount of 

 capture may have taken place before the deposition of the Upper 

 Boulder-clay; and that the present river-system is recovering from 

 a state of arrested development, due to the 'overloading' of the 

 valleys with Drift deposits and torrential debris during the last 

 glaciation of the area, and to the subsidence (some 60 to 80 feet) 

 which followed it. 



