Geological Society. 429 



pi-essure upon the crust increases towards the poles, the 

 opposite pressure upon the sea-bottom also increases in the 

 same regions, because the sea rises. But the parts not covered 

 by the sea are exposed alone to the increasing pressure from the 

 interior without any exterior counterpressure being developed. 

 Under lower latitudes the same thing takes place. Accord- 

 ing as the crust increases in weight the sea sinks, and the 

 pressure upon the interior increases more rapidly in the 

 continents, where nothing is removed, than in the sea, where 

 the level of the water sinks. Therefore I think that the 

 continents are weak points. The sea's movements weaken 

 the effects of the diminishing centrifugal force for all parts 

 covered by the sea, but the pressure acts with undiminished 

 force everywhere on the solid land, both under low and under 

 high latitudes. Whatever the cause may have been that origi- 

 nally determined the distribution of land and sea upon our 

 globe, it seems to me that we may reasonably assume that the 

 sea's mobility is a preservative force, which perhaps has con- 

 tributed to make the continents and oceans, broadly speaking, 

 retain their form from the most ancient times until now. 



There is also reason to believe that the continents may yield 

 more easily than the bottom of the deep sea, and that they 

 may rise and sink more readily. And they are also separated 

 from the depths of ocean by lines abounding in volcanoes, 

 lines of weakness, where the connexion between the parts of 

 the crust seems to be weaker than elsewhere. Processes of 

 plication may also perhaps be a consequence of the movement 

 of " tables " not being of the same kind on both sides. 



But the boundaries between the deep ocean and the foot of 

 the continents do not everywhere coincide with the existing 

 shore. Along the coasts there are often shallow tracts in the 

 sea. These are the foot of the land which the sea has flooded, 

 and the great deep sea only commences further out. 

 [To be coutinued. j 



L. Proceedings of Learned Societies. 

 GEOLOGICAL SOCIETY. 

 [Continued from p. 363.] 



March 6, 1889.— W. T. Blanford, LL.D., F.ll.S., President, 

 in the Chair, 

 ^PHE following communications were read : — 

 -■- 1. " On the Subdivisions of the Speeton Clay." By G. W. Lamp- 

 lugh, Esq. 



This paper gave the results of a long series of observations made 



