ANNIVERSARY ADDRESS OF THE PRESIDENT. Iv 



Warbarrow Bay, Lulworth Cove, and to the Man-of-War and Durdle 

 Coves, where the last coast exhibition of the Wealden rocks is ob- 

 servable. Mr. Weston considers that he has fully established the 

 extension of the Hastings sands as far westward as Ridgway, and 

 he mentions finding the Purbeck beds at the end of the Gorton 

 Range, spreading therefore Mith the Portland beds to the vicinity of 

 Portisham. 



From the different physical conditions under which the oolitic se- 

 ries, and that of the Wealden above it, have been accumulated, all 

 facts tending to throw light on the extension of the various beds com- 

 posing the latter are valuable, as they enable us the better to judge 

 of the configuration of the area under the fitting conditions for the 

 minor and successive deposits. The oolitic series of southern England, 

 there is reason to believe, was accumulated within a gradually dimi- 

 nishing area, from a gradual rise and filling up of the sea-bottom, 

 so that finally dry land with soil and trees growing on it was esta- 

 blished, as for instance near Weymouth. The detritus afterwards 

 accumulated in part of the previously marine area of England, and 

 in some parts of the continent of Europe, is now well understood 

 not to have reached a sea ; and we may suppose the elevation of the 

 land to have gone on gradually for some time, throwing perhaps the 

 sea-coasts further off, though not of course preventing marine 

 accumulations of great importance of the same date in the area 

 now occupied by Europe and even probably in parts of England. 

 As careful observation becomes more extended we may hope to 

 obtain some e^ddence of the coast-lines of the time, as also of the 

 boundaries of freshwater accumulations, whether in great lakes, like 

 those of North America, or on the sides of large rivers. The occur- 

 rence of freshwater deposits is a considerable aid towards our know- 

 ledge of land and sea at different geological times, and the value of 

 getting the extreme points to which certain of them, even minor di- 

 visions of a series like that of the Wealden, may be found to range, 

 is always important. If we imagine a large part of Europe to be now 

 gradually raised 1 000 feet, and then as gradually depressed 2000 feet, 

 and consider the various figures which the different intermixtures of 

 land and water would present, when the solid land was most elevated 

 and most depressed, as also all the modifications during the period 

 of rise and depression, from altered sea-coast lines, the direction and 

 force of tidal streams, changed sub-aerial drainage areas, the courses 

 and variable magnitude of rivers, and the like, we may obtain some- 

 what of an idea of the physical modifications of various kinds effected 

 during the accumulation of the deposits known to us as the Wealden 

 and cretaceous series. We must however carefully guard against 

 supposing that this kind of rise and depression, with its consequences, 

 was anything out of the ordinary course of geological events. Every 

 day brings us evidence of the probable change of even the European 

 area, as regards land and water, at different geological times ; though, 

 of course, as those changes were the more ancient, the more difficult 

 it may be, from continued denudations and a multitude of overlaps 

 by less old deposits, to trace them, and find satisfactory evidence con- 



