520 Ebpobt of State Geologist. 



the topography is that of an almost featureless drift plain. It is 

 traversed by numerous morainie ridges, but they are low and incon- 

 spicuous. The traveler may ride upon the railway train for hours 

 without seeing a greater elevation than a hay stack or a pile of saw- 

 dust. The divides are flat and sometimes swampy, the streams muddy 

 and sluggish. The valleys begin on the uplands as scarcely percepti- 

 ble grooves in the compact boulder clay, widen much more rapidly 

 than they deepen and seldom reach down to the rock floor. 



"The Northern Plain.— The portion of the drift plain north of 

 the Wabash river is more varied than the central plain, and comprises 

 several regions which differ materially in character. A small area 

 around the head of Lake Michigan is occupied by sand ridges and 

 dunes, partly due to a former extension of the lake and partly to 

 present wind action. Some of the drifting dunes are more than 100 

 feet high. This region is separated by a belt of morainie hills from 

 the basin of the Kankakee, which contains the most extensive marshes 

 and prairies in the State. This region also is traversed by numerous 

 low ridges of sand, the origin and character of which are not yet well 

 understood. Many of its features are probably due to the fact that 

 during the retreat of the ice-sheet it was temporarily occupied by a 

 glacial lake, which received the wash from the high moraines to the 

 eastward. Northeastern Indiana is the region of high moraines, and has 

 a strongly marked character of its own. A massive ridge of drift, 25 

 miles wide, 100 miles long and from 200 to 500 feet thick, extends 

 from Steuben County to Cass County and is joined by several smaller 

 branches from "the northwest. This is the Joint moraine of the Erie 

 and Saginaw lobes of the Laurentide glacier. Much of its surface is 

 extremely irregular, presenting a succession of rounded domes, conical 

 peaks, and winding ridges, with hollows of corresponding shape be- 

 tween, which are occupied by innumerable lakes and marshes; the 

 highest points are 100 to 300 feet above the level intermorainic inter- 

 vals. A large proportion of the material is sand and gravel. A small 

 area in eastern Allen County is a part of the bed of the glacial Lake 

 Maumee. 



DRAINAGE. 



"The general slope of Indiana is to the southwest, as indicated by 

 the course of the Wabash Eiver and its tributaries, which drain two- 

 thirds of the State. Of the remaining third one-half is drained di- 

 rectly to the Ohio and one-half to Lakes Erie and Michigan and to the 

 Mississippi through the Illinois. 



