E. R. Scheffel 
158 
the confluence of three streams, the North and South Forks and 
Raccoon creek. These streams form a hydrographical basin which ! 
is very nearly coextensive with the county lines. To the west i 
of the headwater portions of the North and South forks, narrow- 
ings followed by decided flarings are noted. By correlating these 
narrowings and following the most unbroken line of high rock 
altitudes the conclusion is reached that a former divide passed 
through Granville^ in an approximately north-south direction. 
tt 1 
DRAINAGE CHANGES [ 
Before considering the cause of the diversions in this area it 1 
may be advisable to give a general discussion of the subject, drain- 
age changes. I 
The causes for such changes may be somewhat arbitrarily j 1 
divided into three heads, ^ though it is quite possible for two or all | 
to be inextricably associated. These causes are piracy, glaciation, I 
and diastrophism. Others, less important and more localized, will 
be omitted.^ ' [| 
I. Piracy.^ This term is applied when one stream ‘Tteals’'^ ij 
another. Primarily piracy is resultant from the more rapid head- | 
water growth and deeper cutting of the pirate stream as compared | 
with the robbed or beheaded drainage line. Davis gives a dramatic 1 
account of the contest for supremacy between the east and west j 
flowing streams draining the Blue Ridge. ^ The entire Appalachian j 
system is also cited as witnessing many such contests. ji 
Though these contests may not represent in every instance typ- | 
ical cases of piracy, still, in a broad sense, when by the greater ! 
relative growth of one stream its divide migrates, thus lessening S 
the drainage area of another, the first has in reality robbed the | 
second. 
nV. G. Tight: Bull. Set. Lab. Denison Univ., vol. viii, part ii, p. 36, 1894. ^ 
^ F. Leverett: Glacial Formations of the Erie and Ohio Basins, Monograph xli, | 
U. S. Geological Survey, p. 160, 1902. | 
^Ihid., pp. 196-200. I 
®G. D. Hubbard: The Ohio Naturalist, voL viii, p. 349, 1908. A. C. Lane: | 
Bulletin of the Geological Society of America, vol. x, p. 12, 1899. j 
®L Bowman: Journal of Geology, vol. xii pp. 326-334, 1904. j 
^ R. D. Salisbury: Physiography, p. 176, 1907. | 
®W. M. Davis: Bulletin of the Geographical Society of Philadelphia, yo\. iii, pp. 
213-244, 1903. 
