30 president's address. 



to 76 feet also (the highest being the Eouvet patch, 75*10 

 feet), and the presence of pebbles in the clay, which must have 

 originated from some higher beach not yet localised, possibly 

 completely removed at the time of the distribution of the clay. 



But the evidence before the Society now adds to the 

 number of explanations, for above the level of the highest 

 sea-washed rock is found the planed and contorted rock 

 surface — a phenomenon which must have a different expla- 

 nation. 



Professor Prestwich tells us that our clays are locally 

 produced during the submergence, and that they were spread 

 over the island by the action of currents of water during the 

 sudden rising of the submerged island in a series of intense 

 shocks.* Against this we now must place the fact that the 

 clay rests immediately on the planed rock, where the latter 

 occurs, and that all the usual forms of marine life are entirely 

 wanting in the clays, its stratification and its rounded grains 

 being the only sign of water action. 



Having discovered the planed-off surface of the rocks 

 composing the hills, we are not reasoning wildly if we refer 

 the cliff heads to the effect of aerial cold ; the one supports 

 the other. The angular pieces of rock, which have only fallen 

 from above and rest everywhere on the old raised beach, may 

 have well originated during a cold period. If this reasoning 

 is correct we have before us the problem of accounting for 

 submergence on the one hand and aerial denudations during 

 extreme cold on the other. 



The sequence of events would seem to be something like 

 this. A submergence of the island to the level at least of its 

 highest summit. The continued action of the sea breaking 

 down all the cones and peaks on the upper plateau and pro- 

 ducing the present fairly flat table land. The sea, permeating 

 into the rock during that period, decomposed the rock to a 

 considerable depth. This submergence is proved beyond 

 doubt, nor need it be questioned because it is consistent with 

 the evidence of the surrounding coasts. From Scotland to 

 Cornwall, on both sides of the Channel, we find the same 

 evidences of submergence. 



Following the submergence, if we may give weight to the 



evidence of glaciation. came a period of elevation and local 



glaciation. The decomposed and weathered rock breaking up 



in all directions under the action of the cold falling from high 



to low levels, forming the cliff heads as far as their rubble 



* On certain phenomena belonging to the close of the last Glacial Period by 

 Professor Prestwich. Fols, 43 and 27. 



