160 PLEISTOCENE OF INDIANA AND MICHIGAN. 



border district is generally between 50 and 75 feet and above the plain on the inner or eastern 

 border 100 to 150 feet, the country to the southeast being lower than that to the northwest. 



The topography of the southwestern portion of this series of moraines in Cass County and 

 northern Miami County, Ind., is of a swell and sag type in which there are few basins. The 

 swells are 10 to 40 feet in height and are closely aggregated, giving the moraines a strong expres- 

 sion compared with the nearly plane district to the northwest. Lake basins become con- 

 spicuous in southeastern Fulton and northwestern Wabash counties and continue numerous all 

 along the morainal belt to the northeast. They are much more prominent on the northwestern 

 or outer slope than on the southeastern or inner slope and are especially numerous where moraines 

 of the Saginaw lobe connect with these moraines. The largest lakes exceed a square mile in 

 area, and one, James Lake, has an area of 2.6 square miles; the majority, however, cover but a 

 small fraction of a square mile and some occupy but a few acres. Many of them have depths 

 50 to 75 feet or more below the level of the outlets and more than 100 feet below the surrounding 

 parts of the moraine. James Lake, with a reported depth of 87 feet, has on its eastern border 

 hills that rise more than 100 feet above the water surface, thus giving the basin a depth of about 

 200 feet below the neighboring hills. The highest knolls along the moraine are probably those in 

 northern Steuben County, which rise more than 100 feet above bordering sags. Knolls 50 to 

 60 feet in height are found at short intervals as far southwest as northern Wabash County, but 

 most knolls are only 20 to 40 feet high and many of them rise less than 20 feet above the border- 

 ing sags. On the inner slope of the moraines few knolls exceed 40 feet in height and the general 

 expression is much less varied than on the outer slopes. Marshes and nearly plain tracts are 

 also much less common on the inner slope than on the outer. In places on the outer slope 

 sharp ridges known as "hogbacks," some of which perhaps are to be classed as eskers, are not 

 uncommon; they are, however, very short, none exceeding a mile in length having been observed. 

 They commonly form the borders of lake basins; one lake in Steuben County has received the 

 name "Hogback Lake" because of its close association with one of these ridges. 



On the outer slope of the moraine deep indentations show where lines of glacial drainage 

 lead away from the moraine. In Steuben County these glacial channels have then heads on 

 the inner border of the moraine and thus completely traverse the moraine. One of them is 

 occupied by Turkey Creek, another by Pigeon River, and a third by Concord Creek and a string 

 of lakes tributary to Crooked Creek. 



STRUCTURE OF THE DRIFT. 



COMPOSITION. 



It is somewhat difficult to set forth clearly the structure of this massive morainic belt 

 because of the great differences it displays both horizontally and vertically. Extensive areas 

 in the southwestern part and along the inner or southeastern slope of the belt are covered with 

 clayey till, but many of them are underlain by thick deposits of sand and gravel. The clayey 

 till is apparently thickest in the low-lying southwestern part of the belt in Cass and Carroll 

 counties. 



The outer slope of the belt of moraines shows extreme variability in surface structure, the 

 deposits ranging from stiff clayey tiU to coarse cobble and gravel. There are no extensive areas 

 of any one kind of deposit. However, gravelly and sandy drift seems to increase and clayey 

 drift to decrease from the main crest of the belt toward the outer border. The gravelly and 

 cobbly knolls and ridges are more or less definitely related to and grouped around the heads of 

 the gravel plains that lead away from the moraines and that were formed by the waters dis- 

 charged from the ice. Much of the drift on the outer slope is a loamy sand, not definitely assorted, 

 but looser textured than the till of the main crest and the southeastern slope. Local occur- 

 rences of very stiff clay, however, were noted. 



In northeastern Lagrange and northwestern Steuben counties a very sandy tract with 

 uneven surface, containing both basins and knolls, rises abruptly at its western edge into an 

 elevated gravel plain. This sandy tract was probably covered by the Huron-Erie ice at the time 



