102 Hayesand Campbell—Appalachian Geomorphology. 
be considered. Local diversion of small streams may very likely 
have taken place by folding, but the drainage at the close of the 
Cretaceous cycle was essentially the result of spontaneous ad- 
justment of the streams to the structure surface revealed by 
erosion. The chief difficulty in deciphering the record of this 
drainage development is to determine how much of the adjust- 
ment took place within this cycle and how much before its 
beginning. 
Drainage of northern Virginia—In the northern portion of the 
province the main streams held their westward courses across 
the rising folds and found an outlet in the shrinking mediter- 
ranean sea. At some time during the early part of the cycle a 
depression occurred in the present piedmont plain, in which the 
Newark sediments were subsequently deposited. This depres- 
sion was different from the purely Appalachian type of synclinal 
fold, more nearly resembling those uplifts described in Part I— 
slight orogenic movements by which the surface was somewhat 
broadly arched or depressed, but unaccompanied by any per- 
ceptible folding of the rocks. This eastward tilting produced a 
decided effect upon the drainage of the northern portion of the 
province. ‘The headwaters of the former streams were soon re- 
versed by the pronounced eastward slope and the divides were 
forced back some distance from the margin of the Newark ‘sea. 
Thus the Potomac, the James and the Roanoke had their birth 
in the subsidence which preceded the deposition of the Newark 
formation, and presumably in the very earliest stages of this 
cycle. ‘The influence of this eastward tilting evidently dimin- 
ished toward the south, for the Potomac drains more of the Ap- 
palachian valley than the James,and the James more than the 
Roanoke, while the New-Kanawha holds its original westward 
course, unaffected by any tilting which may have occurred about 
its headwaters. 
Drainage of the southern Appalachian Valley—South of the New- 
Kanawha basin the main streams also doubtless persisted across 
the rising folds for a short time after the beginning of the cycle, 
although in this region the chances of diversion to synclinal 
troughs were much greater than farther northward, even with ex- 
tremely slow folding. As soon as the folds had risen sufficiently 
high so that erosion upon their flanks and summits became active 
and beds of varying hardness were exposed, southward flowing 
axial streams, aided by the general southward pitch of the axes, 
