349 
traced only by means of borings, and these are so few and so poorly distrib- 
uted as to be inadequate to our needs.” 
Tight favors a northwestward discharge of the Portsmouth river and 
so maps it in Plate I, Professional Paper, No. 15 (109). 
Bownocker has studied the deep borings of west central Ohio and finds 
evidence of a deep channel running from Anna to Celina, north to Rockford 
and west into Indiana, as far as Grant county, where no borings by which 
it may be traced are found (10, 11). This old channel may be a continua- 
tion of the preglacial stream in question (Portsmouth river), and Leverett 
suggests that it may be a tributary of the Wabash (65: 183-4; see 109, p. 
93 and Pl. 1), but adds: “The size of the valley indicates that it drained 
at most only a few counties of western Ohio.” 
Between Manchester, Ohio, and Madison, Indiana, the Ohio crosses 
three cols, which means that it is the united parts of four basins. The 
Licking and Kentucky rivers are thought by both Bownocker and Fowke 
to have been united to form a single stream at Hamilton. Fowke and Tight 
think that from Hamilton it flowed northward along the Great Miami re- 
versed. Leverett, who opposes the idea, states, “It is probable that the old 
drainage south from the latitude of Dayton followed nearly the course of 
the present line to the Ohio. . . . The old Ohio was entered by the 
Great Miami near Hamilton. The latter stream makes slight departures 
from the line of the old Ohio below Hamilton, the old Ohio channel being 
in part farther west than the Great Miami.” (65, p. 184.) 
Fowke believes that the old channel between Hamilton and the mouth 
of the Kentucky was eroded by the Kentucky river, instead of the Ohio. 
He says: “In other words, that stream, instead of following the present 
Ohio as it does now, or flowing across Indiana, turned to the east and 
north and joined the Licking at Hamilton. There is no other channel 
through which it could have gone. . . . From Hamilton northward 
the old river bed is filled with drift and has not been traced. There can be 
no doubt, however, that it joined the old Kanawha (Chillicothe) north of 
Dayton, probably in the neighborhood of Piqua.” (386). The preglacial 
head of the Ohio is by this theory placed at Madison, Indiana. 
The present course of the Ohio is due to the action of the ice-sheet 
which dammed the north flowing streams, forming lakes in the basins which 
overflowed at the lowest point in the divides between basins to the next 
lower neighboring basin. The lakes endured sufficiently long for the present 
Ohio to establish itself in the course which it now follows (86, 109). 
