JOHNSON: TALLULAH DISTRICT. 
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the Chattahoochee Ridge), is finely developed, and one may look 
down some 500 feet upon the low rolling plain from which he has 
just ascended, or out across the upper level to where the Tallulah 
Mountains and other peaks rise sharply from the surface of this 
higher peneplain. In considering this escarpment in its broadest 
relations, we have already seen that it is a marked feature of southern 
Appalachian topography, with a height of from 1500 to over 2000 
feet in northwestern North Carolina and southwestern Virginia, 
decreasing to 500 or 600 feet in the Tallulah district, becoming less 
distinct and having a height of but 200 or 300 feet in the vicinity of 
Gainesville, while it seems to disappear entirely before one reaches 
Atlanta. A good description of the northern portion of the escarp¬ 
ment is given by Davis ( 03 ) in his paper on “The stream contest 
along the Blue Ridge.” 
The origin of this escarpment is a problem of great interest; but 
while it bears a close relation to the history of drainage modifications 
in the Tallulah district, it does not constitute an essential part of the 
problem of river capture now under consideration. I shall therefore 
content myself with a brief statement of two hypotheses which have 
been advanced in explanation of this striking feature. 
According to Hayes and Campbell an erosion level known as the 
Cretaceous peneplain has been unsymmetrically warped along a 
northeast-southwest axis in such a manner as greatly to accelerate 
the activity of the stream flowing down the steeper slope of the uplift 
toward the Atlantic Ocean. As a result of their great activity the 
streams of the Atlantic drainage have eaten headward into the arch 
all along its length, developing a new erosion level, the Tertiary 
peneplain, at a lower altitude than the remaining portion of the Cre¬ 
taceous peneplain which suffered warping and erosion (Hayes and 
Campbell, 94 , pp. 75, 76; Davis, 03 , p. 222). 
Professor Davis has suggested that since the erosion level developed 
near the headwaters of a stream which has a long distance to traverse 
before reaching the sea, must be at a higher elevation than a similar 
level about the headwaters of a stream having a short course to the 
sea, we should expect to find the peneplain about the headwaters of 
the Gulf drainage distinctly higher than that about the headwaters 
of the Atlantic drainage. Where these two peneplains “break joint” 
we have an escarpment facing the lower level. Such an escarpment 
is the Blue Ridge. Under this interpretation, it seems to me that we 
