A. Vaughan — Corrugation of the EartJis Surface. 269 



The portion nearest the sinking area would thus be drawn away 

 from the rest of the crust, which would be raised to a higher level 

 by the pressure from below. In this way a normal fault, or succes- 

 sion of such faults, would be brought about. 



Again, the sudden relief from great pressure caused by this means, 

 when the underlying rocks are far above their melting point, would 

 result in their sudden melting. The very high temperature at which 

 this melting may be supposed to be produced will necessarily ensure 

 very complete liquefaction, and aided partly by the pressure from 

 below, and partly by the increase in volume due to melting itself, 

 the molten material will be exuded through the clefts formed in the 

 broken crust, to rise to the surface in a flow of lava. Further, the 

 rupture of the crust would certainly cause an earthquake, and, as 

 we have shown, it would be natural to expect depression or 

 elevation to be a consequence. That earthquakes are often followed 

 by such phenomena is well known. 



Again, the greatest pressure being between the stretched crust 

 and the upward forced interior, the depth at which earthquakes 

 would be generated on this theory seems to accord well with 

 observed results. It merely remains now to point out where such 

 areas as we have considered exist, and to illustrate the effects of 

 the theory by well-known examples. In the first place the earth 

 is flattened at the Poles, so that each Pole is about thirteen miles 

 nearer the centre than any point in the equator. Again, the Polar 

 regions have, for vast ages, been covered by ice, so that the ground 

 is constantly frozen far below the surface ; also the change is very 

 gradual from elevated to depressed areas. 



We should expect then that the Polar regions themselves are 

 sinking, but that the neighbouring regions are rising, and that this 

 should be an effect spread over large areas. These facts seem to be 

 in accord with the observations that whilst Greenland is found to 

 be sinking, Norway is rising. 



A suggestion may here be thrown out as to a possible explanation 

 of the events supposed to have occurred during the Glacial epoch. 



Before the Glacial period there is evidence that the British Isles, 

 as a whole, were above sea-level ; but that during the period 

 subsidence took place and that, after its departure, the Islands 

 again rose. This seems to be in entire agreement with what the 

 above theory would require. During the period of great cold, lasting 

 for an enormous time, the ground must have been frozen to great 

 depths, as is proved by borings in Siberia, where the effects are still 

 very obvious in frozen ground, extending to several hundred feet. 

 In consequence rapid contraction must have taken place beneath 

 the area, together with the transfer of material from below. These 

 two causes combined must have drawn the area down to below 

 the sea-level. On the termination of the period, the Polar regions 

 must again have become the principal area of subsidence, resulting 

 in the gradual upheaval of the neighbouring regions, as evidenced 

 by the raised beaches of Norway and Scotland which characterized 

 the post-Glacial period. 



