600 IO (Cle CANUTE EIGI LION, 
tions: (1) The continents are platforms whose summits are 
accommodated approximately to the sea level by truncation and 
by concurrent circumjacent filling. (2) The normal and the 
dominant feature of each readjustment of the outer part of the 
crust to internal contractional stresses is the sinking of the ocean 
basins and the enlargement of their capacity. (3) The inci- 
dental consequence of the sinking of the oceanic basins is the 
withdrawal into them of an increased amount of the epiconti- 
nental waters and the establishment of a new shore line upon 
the borders of the continent lying at a lower level than the pre- 
ceding one. (4) The main readjustments are periodic and are 
separated by intervening stages of relative quiescence. (5) The 
continental platforms are subject to warping, partly due to the 
lateral thrust of segments of the earth as they sink (especially 
those segments that lie beneath the ocean), partly to internal 
changes of temperature and the intrusion of liquid matter, and 
partly to the settling of the continent when, by any of the pre- 
ceding agencies it has been forced upward beyond the plane of 
isostatic equilibrium, the settling being accomplished through 
the slow quasi-fluid creep of the rock under gravitative stress. 
As a mode of approach to the critical attitudes of sea and 
land which favor the evolution of provincial faunas, two more 
general and systematic attitudes which favor respectively gen- 
eral expansional evolution and general contractional evolution 
may be considered." 
1. Conditions favorable to general expansional evolution of marine 
life—It is to be understood that only that element of marine 
life is here considered which has for its habitat the relatively 
shallow sea water adjacent to the land. Geologically speaking 
we know very little respecting the true abysmal life of the past, 
and only such little about the surface pelagic life as became 
incidentally involved in the terrigenous deposits. In consider- 
ing the shallow-water life adjacent to the land we are, therefore, 
considering practically that phase of marine life which alone 
enters effectively into the geologic record. The conditions 
*These were discussed on pp. 454-459 of preceding number of this JOURNAL. 
