349 



traced only by uicaiis of buriufis, and Uu'si^ 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. 1.3 (10!)). 



Bownoclj:er 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 (05: 18.3-4; see 109, p. 

 23 and PI. I), 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 

 tliink 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 cliannel being 

 in part fai-ther 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 cliannel 

 through which it could have gone. . . . From Hamilton northward 

 the old river bed is filled witli drift and has not been traced. There can be 

 no doubt, howevei', that it joined the old Kanawha (Chillicothe) north of 

 Dayton, probably in the neighborhood of Piqua." (3G). 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 (36, 109). 



