Atlantic Ocean. 
Davis and Wood.] 
388 
[Nov. 20, 
This may be made plainer by refer- 
ence to fig. 4, 1 which gives a gen- 
eral northwest-southeast section of the 
region. The profile that would have re- 
sulted from the post-Triassic monoclinal 
faulting and tilting without erosion may 
be typified b}^ the uppermost dotted out- 
line. The ocean then stood at the 
Schooley baselevel, AC, with the shore 
at A. Long continued erosion during a 
stand of the land at about this position 
reduced the surface to the Schooley base- 
level plain, FED, the shore waves having 
in the meantime eaten into the land.from 
A to D ; the land waste is transferred to 
the ocean bottom A B K. The soft Tri- 
assic portion, DE, of the old plain was 
worn down sooner and smoother than 
^ the hard crystalline portion EF. At 
g about the end of Jurassic time, the old 
plain was somewhat depressed, especially 
to the southeast ; the ocean level rose 
from C to H, and the shore line was 
thereby carried inland from D to E. 
F The rapid transgression of the sea over 
the smooth plain, DE, did not allow the 
waves time to gather much Triassic ma- 
terial for the sediments that were formed ; 
but when the advance of the shore line 
was checked by reaching the higher 
ground at E, marls and sands were sup- 
plied in moderate quantity from the low 
hilly country of slowly disintegrating 
crystalline rocks. These form the rela- 
tively thin Cretaceous deposits that were 
spread over the new sea-bottom, EDK, 
thin towards their shoreward margin, 
but thicker in deeper water. It is likely 
that there were minor oscillations of sea 
VThe location of this section and of several other diagrams is given in fig. 8. 
