Editorial 



The suggestive article by Professor Schwarz relative to a former 

 land connection between Africa and South America (p. 8i) fur- 

 nishes an excellent illustration of the vital dependence of our studies 

 of most large problems on fundamental conceptions of the early- 

 states of the earth. An essential part of his argument from the 

 nature of the rocks of the oceanic islands hangs upon theoretical 

 views as to what the specific gravities and the structures of the 

 oceanic and continental portions of the crust, respectively, should 

 be, under alternative assumptions relative to the configuration of 

 the ocean surface. If the average specific gravities of the sub-oceanic 

 and of the sub-continental sectors were the same, the waters of the 

 hydrosphere would be drawn up about the continental masses, and 

 would add their gravity to that of the continents, and thereby increase 

 the differential stresses within the lithosphere and tend to depress 

 the continents. To sustain stresses of such magnitude, the rigidity of 

 the lithosphere must be assumed to be very effective, and the agencies 

 of elevation must have worked against these stresses ever since the 

 continents were formed. 



If, on the other hand, the sub-oceanic rocks are suihciently higher 

 in specific gravity to counterbalance (with the aid of the overlying 

 oceanic waters) the weight of the continental protuberances, the 

 surface of the ocean must be more nearly spheroidal and the htho- 

 sphere much less affected by differential stresses. 



To test these alternative hypotheses in the most direct and positive 

 way, there is need that geodetic measurements of the ocean surface 

 be extended outward from the continents on chains of islands as 

 far as possible, and that pendulum observations be made on the 

 oceanic islands and on the open ocean itself, so far as practicable. 



But even if such determinations were at command, there would 

 still be need, whatever their results, to take careful note of the dif- 

 ferent inferences that legitimately arise from alternative views of 

 the earth's genesis, if we are to proceed on safe grounds of inter- 

 pretation. The criteria deduced by sound reasoning from a molten 



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