358 SEE— THE CAUSE OF EARTHQUAKES. [October 19, 



by Lyell, is inadequate to account for the general lowering of the 

 strand line noticed throughout the world. After his careful study 

 of this question, Professor Suess is unable to adopt any satisfactory 

 explanation of the observed phenomenon, and the whole problem 

 remains an enigma to the investigator of the physics of the earth. 

 An impartial examination of all the arguments leads me to believe 

 that the conceptions of Strabo, as developed into the oscillatory theory 

 advocated by Lyell, is adequate to account for many more of the 

 phenomena of the earth's surface than Professor Suess concedes ; 

 yet it seems not only possible, but even probable, that an additional 

 cause is at work which must contribute somewhat to the general 

 lowering of the strand line throughout the world. This additional 

 cause is nothing else than the secular desiccation of the oceans, 

 brought about mainly by the sinking of the waters into the crust of 

 the earth, where the resulting steam becomes the motive power in 

 earthquakes.^ A certain amount of water is also taken up as water 

 of crystallization in the development of crystalline rocks, which 

 extend somewhat deeper from age to age. 



The view of earthquakes here adopted makes sea water the prin- 

 cipal disturbing cause. Of the water which thus sinks below the 

 crust, an appreciable part, but by no means all of it is expelled by 

 volcanic action; and thus there is a steady accumulation of water 

 deep down in the earth's crust. If this view be well founded, there 

 is thus a secular desiccation of the waters of the globe, depending 

 on the penetration of water to the deeper parts of the crust, and also 

 on the absorption of water by rocks in crystallization and otherwise. 

 How rapidly this process goes on cannot be accurately known at 

 present; but on the basis of data observed within the historical 

 period, we may reasonably hold that the fall of the strand line due 

 to this cause is on the average less than a meter in 2,000 years, and 

 most likely of the order of one-tenth of this amount. 



The desiccation here postulated seems to be a vera causa, and 

 this process, in connection with the oscillatory movement of the 

 land recognized by Lyell and other geologists as necessary for the 



^ The sinking of the sea bottom when lava is expelled from under it also 

 increases the capacity of the ocean basins, and thus slightly lowers the strand 

 line. 



