Features of the Earth's Surface. 461 
miles wide, still the neigrs necessary would be enormous. 
t 
phenomena went on together pari passu; and, therefore, the 
surface was never convex at all, but nearly or quite horizontal 
all the time. Subsidence under such circumstances might pe 
duce horizontal tension or stretching of the lower strata, but 
could not produce horizontal crushing and plication of the 
upper strata. 
* “Some points in American Geology,” this Jour., May, 1861. ; 
* Whitney: Mountain Building, p. 101. Hunt, American Geology, this Jour., 
May, 1861. 
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