DIASTROPHISM AND THE FORMATIVE PROCESSES — 533 
tendency is to rise. If it can be supposed to have been previously 
lifted beyond the point of equilibrium it would first be reduced to 
equilibrium, after which rise would follow. The most that is to be 
rationally assigned to the weight of sediments on the continental 
borders is a downward bending of the edges while the adjacent land 
surface rises under denudation, involving a local tilting of the surface 
toward the sea. The mechanism thus pictured offers no good 
ground for the explanation of a great sea-transgression. That the 
normal tendency of the continents is to rise and has been so through- 
out geologic history is attested by their continued existence in spite 
of the constant removal of their material, as also by their periodic 
rejuvenation and by the continuity of the land life since it began its 
record. If effective subsidence had habitually co-operated with 
denudation the disappearance of the continents would have been 
inevitable. The process of subsidence is not, therefore, normal to 
the continents. (Subsidence is of course here used in the conven- 
tional sense, subsidence relative to the mean earth surface. The 
mean surface itself may of course approach the center without 
affecting this relation.) Local or regional subsidence occasionally 
akes place, but for the continents it is exceptional rather than 
normal. Apparent subsidence is a common phenomenon arising 
from the filling of the oceanic basins and the lifting of the sea-level. 
Local subsidence, as one of the features of warping and faulting, is 
of course presumed to be nearly as common as the warping itself, 
but it is of course connected with a complementary uplift. Sub- 
sidences of these local types are not tributary to the parallelism and 
wide extension of the great marine deposits nor to the life adapta- 
tions of the great transgressive seas. The consistent elucidation of 
these constitutes the supreme problem of the geologic seas. 
There seem therefore to be very cogent reasons for abandoning .the 
traditional view that the systematic sedimentations and the systematic 
evolutions of faunas of the higher order are to be assigned directly to 
vertical or epeirogenic movements of the earth’s crust. 
