236 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
Deductive Study of River Capture. 
As pointed out in the introduction to this paper, a process of river 
capture has been supposed by some to account for certain of the 
topographic features of the Tallulah region, although others have 
not been able to explain all of the features on the basis of this theory, 
and have been led to suggest an alternative theory. It will be well 
for us to examine into the process of river capture, therefore, and 
determine what features should be produced as a result of such cap¬ 
ture. We may then compare the results of our deductive scheme 
with the actual facts observed in the field’, and see whether or not 
there is sufficient agreement to justify the acceptance of the capture 
theory. 
Let us imagine that because of the warping of a peneplain and 
accelerated erosion along one side of the axis of uplift, or because 
of unequal lengths of rivers producing two parts of the same pene¬ 
plain at different elevations, we have two erosion levels breaking 
joint along a marked escarpment, as shown in figure 6. On the 
