ABSTRACT OF YOLUME. 



Chapter I. Introduction. — The area treated in this monograph extends from 

 the Genesee Vallej' 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 Alleghen}^ and Ohio rivers. It includes the old drift of north- 

 western Pennsylvania, the Illinoian drift of Ohio, Kentucky, and southeastern 

 Indiana, and the Wisconsin drift of the Maumee-Miami, Scioto, and Grand River 

 lobes, as well as the drift of western New York. It includes the portions of the 

 glacial Lakes Maumee, Whittlesey, and Warren, which border the Lake Erie Basin 

 on the south and west, and also their westward outlets. 



This chapter presents an outline of previous publications on the glacial geology 

 of the region, and also outlines the geologic formations and the several sheets of 

 drift there present. 



Chapter II. Physical features. — The variations in altitude are great, rang- 

 ing from about 250 feet up to nearly 2,500 feet above sea level in the drift-covered 

 region south of Lake Ontario, and from below sea level if that basin be included. 

 There are series of plains south of Lake Ontario separated hy escarpments, and 

 south of these is a greatly eroded table-land. Farther west are the Grand River 

 and Scioto basins, bordered bj^ eroded table-land, and still farther west is the low 

 plain of the central Mississippi Basin, whose eastern border is found in western Ohio. 



Chapter III. Drainage systems. — This discussion includes not onlj' a descrip- 

 tion of the present systems of drainage, but also directs attention to important 

 changes of drainage that have occurred and attempts to determine to some extent 

 the causes of these changes. 



Chapter IV. The drift border, or glacial boundary. — It is found that the 

 glacial boundary is not a unit, but is formed in part by the border of the Wisconsin 

 drift, in part by the Illinoian drift, and in part by a sheet of drift that appears to be 

 still older than the Illinoian. 



Chapter V. The oldest drift (Kansan or pre-Kansan?). — This drift, which 

 is exposed outside the Wisconsin drift in northwestern Pennsylvania, is shown to 



