VALLEYS AND OF COOMBE ROCK. 



371 



limit of the ice, such a frozen belt is always found. It may be 

 observed, however, that the frozen lands of Siberia and North 

 America are either lowlying or have been much glaciated. Con- 

 tinned glaciation and denudation have destroyed most of the bolder 

 features ; we therefore do not commonly find steep hills of soft 

 rocks, like those that were so rapidly denuded in England. 



. In the south of England denudation during the continuation of 

 these conditions seems to have been enormous and extremely rapid. 

 If the time had not been short, all soft rocks would soon have been 

 planed down to one gently undulating surface, like the plains of 

 Russia and Siberia. 



It is not here necessary to try to correlate the Coombe Bock with 

 any particular Glacial deposit of other parts of England. All that 

 I have attempted to show in this paper is, that a certain type of 

 denudation must necessarily have acted in the frozen lands, bare of 

 snow, during some part of the Pleistocene Period. Tundra-conditions 

 may have recurred several times. Probably some of the so-called 

 " Interglacial Deposits " of the north merely show a deficient snow- 

 fall and consequent change to these conditions. An actual amelior- 

 ation of the climate need not have taken place. However, the 

 further consideration of these points must remain for future work. 



Discussion. 



The President observed that whatever difference of opinion 

 there might be as to the subject of the origin of dry valleys in the 

 Chalk, it was one which would always excite the interest of those 

 who lived amongst them. 



Prof. Seeley stated that Canon Gover had long studied the dry 

 valleys of this part of the South Downs, and had come to the con- 

 clusion that in their upper portions they were excavated by glacial 

 ice, and in their lower parts by the action of running water. Last 

 Easter he went over the evidence with Canon Gover and examined 

 in detail the Eindon valley and adjacent districts ; but he failed to 

 find any proof that ice had played an important part in relation to 

 their formation. On the contrary, all the facts seemed to show that 

 these valleys were in the main the work of the sea, during a time 

 of comparatively rapid change of level of the land. The valleys run 

 up inland from the inland cliff of chalk, as they might be expected 

 to do if they were formed by erosion along lines of jointing. It 

 was manifest that the valleys had formerly been filled with a not 

 inconsiderable volume of water ; and high up, at various levels, 

 the hills were sometimes capped with a brown clay full of broken 

 flints. He.believed that this accumulation had been swept into its 

 present position by tidal waters during the time when the land was 

 being submerged and the waters were working up the valleys. At 

 a much lower level, just before the valley widens out, there are 

 deposits of rolled flints two or three feet thick, which creep up the 

 slopes, and differ as much from gravel as the deposits on the hills 



