334 Geological Society : — 



lithological characters being found untrustworthy. Certain struc- 

 tural features of this area are thus brought to light and discussed. 



On the east of the Cuckmere River, the beds examined are found 

 to be nearly horizontal. On the west side they are bent into a 

 sharp uniclinal fold, striking east and west. Seaford Head repre- 

 sents a remnant of this fold, the westerly extension of which is 

 destroyed by marine erosion. The low ground between Seaford 

 and Chyngton occupies the trough of the fold, from which dip- 

 slopes rise gently to the north and sharply to the south. There is 

 thus formed a true synclinal depression striking westwards, with a 

 low pitch, into the English Channel. The complete disappearance 

 of the fold on crossing the Cuckmere cannot be satisfactorily 

 explained by the normal process of dying-out, the distance being 

 too short for so rapid a recovery. It is suggested, therefore, that a 

 transverse fault may exist beneath the alluvium of that river, 

 thus, perhaps, accounting for the narrow gorge at Cuckmere Haven. 

 The top of the zone of Marsupites testudinarius, which lies in an 

 approximately horizontal position at about the level of the 300-foot 

 contour on one side of the river, sinks below sea-level in the trough 

 of the fold on the other side. The fault, if it exists, seems to die 

 away rapidly northwards, since no trace of it has been detected 

 higher up the valley towards Alfriston. This feature would be 

 expected from the nature of the movement. The relation of the 

 Seaford fold to the main flexures of the South Coast is considered, 

 and it is suggested that this fold represents the eastern termination 

 of the structural area known as the Hampshire Basin — being, in 

 fact, a continuation, en echelon, of the Purbeck-Isle-of-Wight 

 system. 



Certain existing physiographical features are ascribed to the 

 influence of this flexure, which facilitated the retention of the 

 Eocene cover in the synclinal hollow thus formed. A result of 

 mapping the outcrops, also, has been to prove that the numerous 

 dry valleys in this area are not of the nature of 'sinks' or 'dolinas ' 

 but are true valleys of surface-erosion. Attention is drawn to 

 certain features of these valleys. 



A brief comparison is made between the fossils of the inland 

 exposures and those of the cliff-section, the most notable difference 

 being the evidence in the former of a Comdus-k&nd at the top of the 

 zone of Micraster cor-anguinum. 



May 26th.— Prof. W. J. Sollas, LL.D., Sc.D., F.R.S., 

 President, in the Chair. 



The following communications were read : — 



1. ' The Cauldron Subsidence of Glen Coe and the Associated 

 Igneous Phenomena.' By Charles Thomas Clough, M.A., E.G.S., 

 Herbert Brantwood Muff, B.A., F.G.S., and Edward Battersby 

 Bailey, B.A., E.G.S. 



The succession of volcanic rocks in Glen Coe is mainly a series 

 of lava-flows, of which there are three types — augite-andesite, 



