JOHNSON: TALLULAH DISTRICT. 
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upper level let there be a stream, A A 1 , flowing from northeast to 
southwest, with one large tributary, B, coming down out of the moun¬ 
tains from the northwest, while many smaller tributaries, CC, come 
in from either side. We may imagine the larger streams to have 
fairly open valleys. On the lower level let there be a stream, D, whose 
tributaries are eating headward into the upper level, gradually push¬ 
ing the escarpment back toward the northwest. The escarpment 
will be more or less irregular, due to the varying activity of the dif¬ 
ferent tributaries. Let us suppose that E is that one of the tributaries 
which has succeeded in pushing the escarpment back the farthest, 
and that it is about to undermine the stream A A 1 at the point X, 
and so capture its upper waters. Such are the conditions imme¬ 
diately preceding capture. 
Figure 7 represents the conditions immediately after capture. 
At the point X, the captured stream, A, now falls down to the lower 
level of the captor, E, and turns abruptly from its former course to 
the southeast, making what we might call the elbow of capture. The 
stream E is greatly increased in volume, and will rapidly wear its 
