542 E. W. Hilgard on Mallet's Theory of Vulcanicity. 
LeConte’s view, that the first mashing of a geosynclinal 
would produce less heat than later plications,* in which (pre- 
sumably) a greater resistance would have to be overcome, 
seems hardly to be compatible with facts as generally observed, 
away from the Pacific coast eruptions; and his argument is the 
less cogent, as the temperature produced is a function, not only 
of the resistance of the rocks, but also of the dgree and rapid. 
ity of the motions, both of which have been on the decrease in 
late geological periods, in accordance with the diminishing 
rate of contraction of the earth and the increased resistance of 
a 
have characterized the Quaternary period, and are recorded, 
e. g., by the raised beaches of the Korth Atlantic coasts an 
inlets; and by the drift pebbles even now found four hundred 
and fifty feet below the level of the Gulf of Mexico, while the 
emerged formations record a complementary elevation to at 
least a similar extent during the Terrace e is reco 
of an oscillation of near a thousand feet on the Gulf shore 
since the glacial drift epoch, implies at least a corresponding one 
over the greater portion of the area drained by the Mississipp), 
unless that river flowed backward at one time.t Doubtless 
* On the great Lava-flood of the West. This Journ., March, 1874, p. 179. 
} It is a curious fact that in the various hypotheses regarding the oscillations of 
the continental interior during ift e the facts observed on the Gulf 
