224 F. B. TAYLOR ORIGIN OF THE EAETH'S PLAN 



tliin crust. These forces wonld tend to cause the crust to creep away 

 on lines of dispersion from the pole. 



An imaginary plane, like that mentioned above, gently sloping toward 

 lower latitudes and situated beneath the earth's crust just within the 

 zone of rock flowage, would seem to afford a basal slope down which the 

 crustal sheets might move, and the tangential thrust forces exerted in 

 the crust toward lower latitudes would tend to give the crust the requi- 

 site impulse to move. 



We may thus enumerate, in part, the conditions and the tendencies to 

 earth-movements which might be expected to affect the lithosphere on 

 the supposition of a flattening of the poles, like that postulated by Suess 

 in explanation of displaced strand-lines. 



Conclusion 



The displacement of strand-lines by eustatic negative movements is a 

 very different thing from displacement by oceanic oscillations. As was 

 pointed out above, it is only at the end of his exhaustive review of the 

 whole subject that Suess recognizes and accepts the principle of oceanic 

 oscillation. After accepting this principle in explanation of the strand- 

 lines, it seems a little strange that Suess should have made no mention in 

 ''The Face of the Earth'' of the possibility that the same force which 

 caused oscillation of the ocean might be a cause of crustal movements 

 also ; but there appears to be no suggestion of this idea, at least not in 

 the first four parts.^® 



In a later work, however, Suess seems to see the possibility of defor- 

 mation of the lithosphere by a force that flattens the poles in the same 

 manner as he supposes oscillations of the ocean to do for the strand- 

 lines. He says: '^One is inclined to suspect that the formation of the 

 curved chains in Asia, open to the north, stands in some connection or 

 other with the outflow of superfluous earth-mass from the pole — that is, 

 with a flattening of the same.''^^ 



Perhaps these words are not sufficiently explicit to enable one to say 

 that Suess accepts the idea that the forces associated with an increased 

 oblateness of the earth's figure are the cause of polar flattening of the 

 lithosphere, but it is hard to see how he could have had any other cause 



10 Volume IV. containing Part V of Suess' "Face of the Earth," reached the writer a 

 few days before the proof of this paper. A hasty examination disclosed nothing that 

 suggests any important change in the conclusions reached. Chapters VII, IX, X, XI, 

 XIV, XVI, and XVII are of particular interest in connection with this paper. 



^ E. Suess : Asymmetry of the Northern Hemisphere. Appendix to the presidential 

 address of B. K. Emerson. Bulletin of the Geological Society of America, vol. 11, 1899, 

 p. 105. Published in German in 1898, 



