94 



impossible of accomplishment, unless the present physical properties 

 of frozen water were entirely different from what we know them to 

 be. The insuperable difficulties of this theory have been pointed 

 out by many writers, but I may refer to Professor Bonney's " Ice- 

 Work " as giving a moderate resume of the arguments on both 

 sides. 



On page 75 a valuable series of observations as to various beds 

 of gravels, sands, and clays have been collated, many of which 

 undoubtedly afford evidences of ice-action, and many also of 

 aqueous agencies acting with considerable force in washing out, 

 distributing, sorting, and sometimes stratifying the various debris 

 which had been left on land surfaces from sub-aerial denudation or 

 deposited upon them during submergence by floating ice. Some 

 of these deposits must have been formed by the action of icebergs, 

 or of shore ice, as the floating masses grounded and tore their way 

 over the surfaces of the rising land or of shallows on what are now 

 the hill-tops. A large iceberg grounding against the slope of a hill 

 can deposit an immense amount of debris as it slowly melts, much 

 of which may have been brought from its place of origin, whether 

 in Scandinavia or Ireland, and the rest may have been dragged up 

 from the land surface near which it finally came to rest. In this 

 way local deposits, of small size, may be accounted for in the 

 absence of glaciers ; also the existence of boulders and masses of 

 frozen gravel driven into previously existing deposits, as have been 

 observed at Wokingham, Berks, and elsewhere, will find a similar 

 explanation. 



We now approach — with what courage we can — the plateau 

 gravels of the Bagshot Sands, and here we are on more familiar 

 ground. Do these exhibit any signs of ice-action ? The distinction 

 between plateau gravels and river or valley gravels is always 

 recognised, but there can, I think, be no doubt that the plateau 

 gravels are of different ages, as is recognised in the paper before 

 us. It will be best to confine any remarks to the plateau gravel of 

 the Bournemouth area, which caps our cliffs and extends for some 

 miles inland, until interrupted by the valleys of the Stour to the 

 north and of Poole harbour to the west. The leading features of 

 this deposit, as I have observed them during some years' study, are 

 as follows : — 



(1) Our local plateau gravel occurs on high ground only, 

 spread out in sheets of varying thickness from 2 to 10 or 

 12 feet. 



(2) It consists almost wholly of sub-angular flints, some of 

 which have been fractured and splintered before having 

 been subjected to the action of moving water, which has 

 partially rounded their sharper angles. Small splinters 

 are rarely found to the east, but appear more frequently 

 on the western side of our cliffs. Chert and small black 

 pebbles are occasionally found. These flints are not 

 battered, as they would have been if deposited on a sea 

 shore. 



