390 SEE— THE NEW THEORY OF EARTHQUAKES [November 15 



yielding of the earth was unanswerable, and so it is for the globe 

 as a whole; yet this does not disprove the existence of a layer just 

 beneath the crust which in earthquakes behaves as fluid'^ 



In the present researches a theory is developed by which these 

 two views may be reconciled, and it is, I think, clearly proved that 

 in earthquakes there is movement of molten rock beneath the earth's 

 crust. It is this movement of molten rock beneath the crust which 

 produces most of the dislocations, crumpling, folding, and fault 

 phenomena studied in geology. If such a theory is justifiable, it 

 shows us how cautious we must be in drawing final conclusions, and 

 how incomplete all the sciences still are to-day. 



§ 14. Criticisms of the Theory here Adopted. — Not many criti- 

 cisms of weight have reached the writer since the publication of the 

 papers on the " Cause of Earthquakes " and the " Temperature of 

 the Earth," but he may here notice two to which some attention may 

 be given. 



I. A geologist thinks that the absence of volcanoes about the 

 South Atlantic is diMcult to explain. This supposed difficulty is 

 much less real than it seems; for some submarine volcanoes have 

 been known in that region, and a good many submarine earthquakes. 

 The sea is shallow near the borders, but a long tableland is rising in 

 the center, and we have no means of knowing how many disturbances 

 occur in this region, which is comparatively seldom visited by ships. 

 Probably the lava finds an avenue of escape under this submarine 

 plateau, and some sea waves occur from time to time, but the region 

 is too far from land to produce great inundations of the shore. 

 As the land is not yet lifted into a sharp ridge, the mountains do not 

 yet appear above the water, and such eruptions as occur beneath the 



* Since this was written Professor Wiechert of Gottingen has presented 

 to the International Seismological Association in session at the Hague, Sept. 

 21-26, 1907, a report of the chief results of his researches on the internal 

 constitution of the earth. The existence of long vibrations in the tremors 

 propagated by earthquakes, with periods of eighteen seconds or more, reveals, 

 he thinks, the presence of a layer of liquid or plastic material at a depth of 

 about thirty kilometers from the surface. (See report of meeting by Pro- 

 fessor Harry Fielding Reid in Science, Jan. 10, 1908.) Note added Jan. 

 22, 1908. 



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