Drainage Features of the Upper Ohio Basin. 263 



feet or more above the stream. The occurrence of this gravel 

 at low levels cannot be accounted for by creeping or land 

 slides, since, in some places, notably at Kennerdell and two 

 miles below Brandon, the gravels show clearly by their situa- 

 tion and bedding that they have not been disturbed since the 

 stream deposited them. We are not, however, reduced to the 

 one interpretation that the valley had been opened to its pres- 

 ent depth and had southward drainage before the beginning 

 of the glacial period. These gravels are in every observed 

 case situated on sloping points on the inner curves of sharp 

 bends in the river. At such places a stream works outward 

 as well as downward, there being erosion on the outer curve 

 and liability to deposition on the inner curve. It is to be 

 expected, therefore, on the hypothesis that the stream has 

 greatly deepened its channel since the ice invasion, that such 

 deposits should be present, and these deposits do not, we 

 think, necessarily oppose the hypothesis of former northwest- 

 ward drainage, nor that of great erosion since the beginning of 

 the glacial period. . 



The Lower Allegheny-Monongahela- Upper Ohio Basin. — ■ 

 Dr. P. Max Foshay, taking up a suggestion of Dr. J. W. 

 Spencer,* has brought out evidence in support of the hypoth- 

 esis that the Lower Allegheny and Monongahela drainage 

 basins, together with a considerable portion of the upper Ohio, 

 formerly discharged through the Beaver, Mahoning, and Grand 

 river valleys to the Lake Erie basin. f He first called atten- 

 tion to evidence furnished by the elevated base-plane, or gra- 

 dation-plane (200-300 feet above the present beds). He noted 

 the great breadth of this plane on the Beaver, its apparent 

 northward slope and the occurrence on its rock surface of pot 

 holes which appear to have been formed by a north-flowing 

 stream.. This gradation-plane was traced no farther than 

 Wampum, some fifteen miles from the mouth of the Beaver, 

 where glacial deposits become so thick as to make further 

 tracing difficult, but it was thought by him to have followed a 

 direct course along the Mahoning to the Grand river basin.. 



In the studies of the past season, an attempt was made to 

 trace the old gradation-plane of the Beaver from the point 

 where Dr. Foshay left it to the Grand river basin. It was 

 found that the Mahoning route, which is the most direct one, 

 was not a probable line of discharge since the valley, as indi- 

 cated more fully below, is very narrow in the vicinity of the 

 Ohio-Pennsylvania state line, and bears evidence of a reversal 

 of drainage. Nothing was found to oppose the view that the 



* Penn. Second Geol. Survey, QQQQ, 1881, pp. 385, 409. 

 f This Journal, Nov., 1890. 



Am. Joub. Sci — Thikd Series, Vol. XLVTI, No. 280.— April, 1894. 

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