381 
ous stream would permit a lowering of the gradient where previous to 
drainage accession the valley had become somewhat broadened in a com- 
paratively graded condition. But in any case the adjustment of the barbed 
tributaries in the down stream direction of the main stream is the respon- 
sible factor determining the position of the terraces. These terraces have 
an origin unlike any others that have come under the observation of the 
writer. So far as he is aware such terraces have never been described 
before. 
It may be mentioned here that the case of piracy here described is one 
of the same type as that of the famous Kaaterskill Creek of the eastern face 
of the Catskill mountains, New York.” The topographic conditions are 
essentially the same except for magnitude. Kaaterskill Creek has taken 
over about 12 square miles of the head-water drainage of Schoharie Creek, 
the back-slope stream of the Catskill mountains cuesta. On the same 
cuesta :an adjacent scarp-stream, Plaaterskill Creek, has added some 5 
Fig. 6.—Bed-rock terrace northwest of the mouth of the barbed stream one- 
half mile northwest of Borden. This terrace is an example of those being formed 
where the barbed streams come into the main stream. They are due to an adjust- 
ment of the barbed tributaries to the present reversed drainage line as downward 
erosion is taking place. These terraces have an origin unlike any others known to 
the writer. ’ Al amie 
square miles to its drainage by successive piracy. Farther south, Sawkill 
Creek has stolen some 10 square miles from a westward flowing stream, but 
this case is not a case of successive piracy. It was perhaps largely brought 
about by glacial action. It will be re-called that Muddy Fork of Silver 
Creek has added something like 35 square miles to its drainage by succes- 
sive piracy. 
For a brief description of this piracy see: N. H. Darton, Bull. Geol. Soc. Amer., 
Vol. VII, 1896, pp. 505-507. Also, R. D. Salisbury and W. W. Atwood, U. 8S. Geol. 
Sury., Prof. Paper, 60, 1908, pp. 49-50. 
