588 REVIEWS 



The reviewer has given indorsement to this view in Monograph XLI, f/. S. Geo- 

 logical Survey (p. 242), but subsequently, upon visiting the region in company with 

 M. R. Campbell and M. L. Fuller, it was found that the contours of the valley are 

 such as strongly to support the earlier interpretation, and the oxbow channel appears 

 to have been abandoned through a sapping which enabled the stream to pass directly 

 across the neck. 

 Williams, E. H. Kansas Glaciation and its Effects on the River Systein 



of Northern Pennsylvania. Proc. Wyoming [Pennsylvania] Hist, and 

 Geol. Soc, Vol. VII, 8 pp., 11 Pis. and Figs., 1902. 



The early glaciation in the anthracite region removed portions of the roof or cap- 

 ping of the coal, so that it is mined by stripping the drift. The old drift at West 

 Bethlehem has a known thickness of 165 feet. Changes of drainage in the Lehigh 

 River worked out by Joseph Barrell are noted; also evidence that the ice so blocked 

 the Susquehanna near Williamsport that a glacial lake, called Lake Lesley, was 

 formed, which had its discharge into the Juniata valley at Tyrone. Connected with 

 this were several ephemeral slack waters still further up the west branch of the Sus- 

 quehanna and the Sinnemahoning. 



In northwestern Pennsylvania the advancing ice blocked the northward flowing 

 drainage system, as shown by Carll, and the slack water found discharge down the 

 Allegheny past the col at Thompson and down the Tionesta from Barnesville. 

 There was a deep filling of sand and rock meal before the coarse glacial material was 

 spread over this region. 



OHIO. 



Clark, W. Blair. Drainage Modifications in Knox, Licking, and Coshocton 



Counties. Denison Univ., Sci. Lab., Bull. Vol. XII, Art. i, pp. 1-16, 



Pis. I-III, 1902. 



Not examined. 

 Leverett, Frank. Glacial Eormations and Drainage Featttres of the Erie 



and Ohio Basins. Monograph XLI, U. S. Geol. Survey, 802 pp. 26 Pis., 



and 8 text Figs., 1902. 



The area treated in this monograph extends from the Genesee valley in New 

 York westward across northwestern Pennsylvania and Ohio to central and southern 

 Indiana, and southward from Lakes Ontario and Erie to the vicinity of the Allegheny 

 and Ohio rivers. It embraces a district ranging in altitude from about 250 feet up 

 to nearly 2,500 feet above sea-level, the highest points being in southwestern New 

 York, and the lowest on the border of Lake Ontario. There are plains south of Lake 

 Ontario separated by escarpments, and south of these is a greatly eroded tableland. 

 Farther west are the Grand River and Scioto basins bordered by eroded tablelands, 

 and still farther west is the low plain of the central Mississippi basin whose eastern 

 border is found in western Ohio. Attention is directed to important changes of 

 drainage which have occurred, and the causes of these changes are treated briefly. 



The drift border or glacial boundary is not a unit, but is formed in part by the 

 border of the Wisconsin drift, in part by the lUinoian drift, and in part by a sheet of 

 drift that appears to be still older than the lUinoian which may be either Kansan or 

 pre-Kansan. This oldest drift is exposed outside the Wisconsin drift in northwestern 

 Pennsylvania, and is shown to have suffered a greater amount of erosion and weath- 



