526 T. C. CHAMBERLIN 
ancient life. The extent and maturity of these seas has been a 
decisive factor in geologic history. 
5. So too it is scarcely more than reiterating the statement that 
preceded the last to say that the typical sediments of the shelf-seas 
at all geologic ages were of the types that depend on agitated 
waters. The sediments were assorted and spread out with notable 
uniformity, continuity, and exceptional horizontality over wide 
tracts because of the conditions of formation. 
6. The shelf-seas were spread upon the continental platforms. 
Diastrophic sea-basins may be set in between continents (Medi- 
terranean, Caribbean, etc.) or be sunk within the continental plat- 
forms, but the gradational seas lay upon terraces either built out 
from the upper edge of the continental platforms or cut back on the 
upper edge of the platforms, or else were flooded forth upon the 
lower parts of the platforms by the partial filling of the ocean basins 
with sediment. They were technically epicontinental, while the 
diastrophic seas were usually intercontinental or intracontinental. 
Of course shallow diastrophic basins may be so formed as to be in a 
sense epicontinental, but not in the constructive sense here applied 
to the sea-shelves, and of course there were composite types not 
belonging wholly to either class. 
7. Abandoned beds of shelf-seas were transmitted to later periods, 
sometimes intact, oftener ‘mutilated, and thus became important 
inheritances. Diastrophism may affect distant ocean basins, 
increasing their capacity and drawing off the waters from above a 
sea-shelf, leaving it intact. The shelf may continue to escape dis- 
turbance until the inwash from all the lands of the globe so far fills 
the common sea-basins as to lift the sea-surface and force the waters 
to return upon the abandoned sea-shelf, introducing a new period of 
sedimentation in close conformity to the old one. Oftener the sea- 
shelf participates in some degree in the deformation, however pre- 
ponderant it may be in distant regions, for the earth body is a 
physical unit and great deformations in one quarter are likely to 
have a greater or less effect in other quarters. The sea-shelf 
inherited by the following period has usually been warped in some 
notable measure and the later terrane is somewhat discordant with 
the earlier one. And yet the gradational work of the earlier period 
