Planation Stream Piracy. 251 
for it. This form of stream piracy is less frequently seen in streams which 
are approximately equal in size. Where such cases occur it is probable 
that one stream does not cause the piracy by lateral planation more than 
the other, but they may be mutually responsible. In any case the stream 
which is deeper acquires the drainage of the other. Since this type of 
piracy takes place on account of lateral planation, usually by the major 
more mature stream, it is here proposed that this type of stream piracy 
be called planation piracy. 
A Typical Case of Planation Stream Piracy. 
Location and Geography.—The area which affords a typical example of 
planation stream piracy lies mainly in southern Monroe County, Indiana. 
A topographic map of the locality accompanies this paper. The area as 
mapped laps somewhat over into Lawrence County. Some seven square 
miles are included in the mapped area, the larger part of which lies in T. 
7TN., R.1 W. The portion of the area in Lawrence County lies in the next 
township to the south. A small portion of the mapped area is included in 
the extreme southeastern part of the Bloomington Quadrangle area. The 
case of piracy is about two and one-half miles east of Harrodsburg station 
and just south of the little village of Fairfax. The area is some twelve 
to fourteen miles south of Bloomington. 
The area is cut by the intrenched valley of Salt Creek. The valley on 
approaching the area from the north makes an abrupt turn to the west and 
northwest, and then again turns to the south when within three-fourths 
of a mile of Harrodsburg station. It leaves the area trending in a 
southeasterly direction. These abrupt turns in the valley of Salt Creek 
have given rise to an upland mass of land partly surrounded by Salt 
Creek valley. The individual drainage of the upland is by rather minor 
streams, chief among which are Upper and Lower Cut-off creeks. These 
streams are not more than two miles in length. Clear Creek which heads 
near Bloomington enters Salt Creek near the southwest corner of the 
mapped area. 
The area is rather sparsely settled and most of the steeper slopes are 
wooded. The gently rolling upland area and the broad valley of Salt Creek 
are under cultivation, but no part of the area is attractive from the stand- 
point of agriculture. 
Topography and Relief—The topography is shown specifically upon the 
accompanying topographic map which has been prepared to show the out- 
standing topographic features and their relationships. The area has a max- 
imum relief of slightly over 250 feet, extending from the valley of Salt 
Creek which has an elevation of about 500 feet to the higher parts of the 
upland which reach an elevation of 750 feet or slightly more above sea 
level. Towards the east side this maximum relief of 250 feet is attained 
immediately between the valley and the upland. The chief topographic 
feature is the deeply cut, but flat-bottomed valley of Salt Creek. This valley 
ranges in width from about one-fourth of a mile to a mile. In places this 
valley is flanked by terraces which are from 10 to 40 feet in height above 
the present flood-plain. For the most part the upland rises abruptly from 
the valley floor with an ascent varying from 125 to 250 feet. The upland 
