Planation Stream Piracy. 259 
the fairly common types of stream piracy as phases of stream adjustment. 
The ideas presented are probably not new, but they are conveniently brought 
together and fairly clearly stated and differentiated. The three types of 
piracy briefly are the headward erosion type, the subterranean type, and 
the planation type. The main body of the paper deals with the details of 
the planation type of piracy. Following the method chosen by the writer 
as the most satisfactory method in presenting a physiographic subject, a 
complete view of the area is given before the details of the main subject are 
presented. The geographic position, the topographic condition, the perti- 
nent geologic factors and the physiographic development of the area are 
presented in order before the details of the stream piracy are undertaken. 
Planation piracy consists of the diversion of the upper portion of a 
stream by the invasion of its valley by the lateral planation of a neigh- 
boring stream. Usually the diverted stream is a minor stream and the 
pirate stream is much larger and is widening its valley by lateral plana- 
tion. The case described is that of Cut-off Creek in southern Monroe 
County, Indiana, a short distance east of Harrodsburg. It is shown that 
the topographic condition of the area, the courses of the streams con- 
cerned, and the passage of glacial waters down the course of the master 
stream (though the area is distant from the glaciated portion of the 
state), were important factors favoring the development of the piracy. 
The principle of static rejuvenation is applied to the diverted and revived 
Upper Cut-off Creek. It is shown that the rejuvenation of the stream basin 
brought about by its diversion gave opportunity for further piracy to take 
place; but piracy of the headward erosion type. The upper, diverted part 
of the parent stream has grown at the expense of the lower part. 
Planation stream piracy is rather common. An excellent example is 
shown on the Lockport, Kentucky, Quadrangle, where Kentucky River has 
invaded the drainage basin of Cedar-Sawdridge Creek and diverted that 
stream some three and one-half miles above its former entrance into the 
main stream. The lower portion of the divided valley is occupied by Pond 
Creek, a stream far too small for the size of the valley. Judging from 
the present gradient of Cedar-Sawdridge Creek, this stream at the time of 
its diversion was approximately 60 feet higher than Kentucky River at 
the place of diversion. The old valley at the divide between Pond Creek 
and the small reversed stream that is etching its way into the Pond 
Creek system is approximately 60 feet above the Kentucky River. A 
potential case of planation piracy is shown on the Buckhorn, Kentucky, 
Quadrangle, which in many respects resembles Cut-off Piracy. Mace Fork 
Creek, like Cut-off Creek is small. It will be divided into approximately 
equal parts, or rather far up stream. When the Kentucky River finishes 
cutting the narrow divide between Mace Creek valley and its own valley, 
the Upper part of Mace Creek will enter Kentucky River as a waterfall 
approximately 110 feet high, a fall similar to the fall of the newly diverted 
Upper Cut-off Creek. Salisbury, and Atwood is Professional Paper No. 
60, U. S. Geol. Sury., call attention to Couler Valley North of Dubuque, Iowa, 
which is described as the former line of the discharge of Little Maquoketa 
River, which stream was diverted principally by the planation of the 
Mississippi River. Bowman‘ has described a case in detail along the Huron 
4Tsaiah Bowman, “A Typical Case of Stream-Capture in Michigan”, Journal 
of Geology, Vol. XI, pp. 326-334, 1904. 
