258 Proceedings of Indiana Academy of Ncience. 
Fig. 4. Oblique view across the “Cut-off Col’ from the southwest. The 
deeply intrenched reversed drainage of the invading portion of Upper 
Cut-off Creek is shown in the back-ground. 
took place. Thus, this planation piracy started normal successive head- 
ward erosion piracy.’ This type of piracy is not yet complete in the area. 
Other small ravines to the west of the col will eventually be taken into 
the upper stream system. This successive piracy proceeding down the 
course of the old parent stream will continue until the gradients of the new 
reversed stream and Lower Cut-off Creek are in a balanced condition. Thus 
Cut-off Col may be expected to migrate west of its present position prob- 
ably as much as a half-mile before the balanced condition is attained. 
The whole basin of former Cut-off Creek had an area of some 1,040 
acres. Immediately following the planation piracy this area was divided 
into an upper basin of approximately 260 acres in area and a lower basin 
of about 780 acres. On account of the headward erosion piracy following 
the planation piracy, Upper Cut-off Creek stream system now consists of a 
drainage basin of approximately 400 acres in area, while the lower 
stream basin has dwindled to approximately 640 acres in area. When the 
‘adients of the present invading portion of the upper stream and the lower 
Fea, have reached a balanced condition, it is probable that the basins 
of the two stream systems will be approximately equal, as it appears that 
some 120 acres in area will be taken from the lower system by the invad- 
ing part of the upper system. 2 
Summary and Conclusion. 
The subject matter of this paper is introduced by a definition of stream 
piracy and a classification of the types. The classification simply defines 
in detail in a paper entitled ‘‘Some Special Physiographie Features of the Knob- 
stone Cuesta Region of Southern Indiana’, Proceedings of the Indiana Academy of 
Science, 1919. The expression ‘successive headward erosion piracy’ is rather 
bunglesome, but should be easily understandable. 
