148 



PROF. EDWARD HULL, LL.D., F.R.S., F.G.S., ON 



the existing surface ; and when we ask ourselves — what agent in 

 nature is capable of such powerful action, we can only reply, 

 the waves of the Atlantic Ocean, impelled chiefly by westerly 

 winds, acting on a gradually subsiding land area, aided by the tidal 

 and other currents which take up the fragniental matter and 

 carry it away to the outer depths of the ocean to form new strata. 



Now, the granitic areas of Devon and Cornwall have, like 

 those formed of stratified materials, been subjected to the agency 

 of denudation, so that the present surface of these areas is 

 altogether different from the original surface after consolida- 

 tion. Much material has been eroded and carried away since 

 consolidation at former periods, chiefly at the close of the 

 Palaeozoic or Primary period. During the cooling and 

 crystalHzing process there may have been portions of the 

 mass protruding into the overlying rock further than others, 

 or they may have been of firmer consistency, and such portions 

 would {cceteris paribus) resist denudation to a greater extent, 

 and remain conspicuous above the adjoining areas. All this is 

 conceivable ; but I do not pretend to precision in a matter so 

 enveloped in difficulties and obscurity. It is permissible, how- 

 ever, to suppose that on the retiring of the sea by reason of the 

 elevation of the land, such more solid masses would be left as 

 isolated pillars, or sea-stacks, to the action of the atmospheric 

 agents, whether frost, rain or wind ; disintegration would ensue, 

 and decomposition along the joint planes. In the case of such 

 granitic tors as the Cheese wring, where, as we have seen, there is 

 a tendency to split along horizontal planes, the ultimate result 

 would be to produce such natural monuments as the 

 Cheesewring itself, and its companions of less elevation. 



Such is the explanation which I venture to offer for the 

 formation of this fine granitic tor. Some of the points in the 

 reasoning are inferential ; others are capable of demonstration, 

 such as the extent to which denudation has . acted over 

 the surface of the country, removing perhaps thousands of feet 

 of strata and rock which once were superimposed on those now 

 forming the surface. Of this denudation we may say, when 

 standing on the surface of the moorland in sight of tiie 

 Cheesewring. " Si momtmentimi quceris, circumspice" Of its kind, 

 few more noble monuments can be found in England. 



Discussion. 



Dr. Logan Jack, F.G.S. — Professor Hull has given us a most 

 interesting and suggestive explanation of this remarkable natural 



