202 PLEISTOCENE OF INDIANA AND MICHIGAN. 



separated and the till plains continue distinct for many miles in northeastern Indiana and 

 northwestern Ohio. 



One till plain occupying an area of 50 or 60 square miles lies in the southern part of Jackson 

 County east of the Hanover interlobate spur. Its surface is gently undulating, with swells 10 

 to 20 feet high, but is decidedly smoother than that of the bordering moraine west of it. Bowlders 

 are about as numerous as on the moraine. It is a region of rather thin drift, rock being struck 

 in many places at 30 feet or less. The till is of loose texture and seems to have considerable 

 sand and gravel associated with it. 



A narrow till plain 8 to 10 miles long and only 2 or 3 miles wide lies in northern Hillsdale 

 County a few miles northeast of the city of Hillsdale. It is very elevated, the greater part 

 of its surface being between 1,100 and 1,200 feet above sea level. The surface is gently undulat- 

 ing but lacks the sharp knolls and basins found in the neighboring moraines on either side. The 

 drift here is 60 to 100 feet or more in depth and contains considerable clayey till, so that many 

 wells are driven nearly to the rock before obtaining water. 



In the southern part of Hillsdale County a till plain on the outer border of the Wabash 

 moraine has a width of about 3 miles and a length of 7 or 8 miles. Its surface is very gently 

 undulating and in places flat. The till is compact and clayey and extends to a considerable 

 depth; wells in it have not reached rock at a depth of 100 feet. 



Another till plain in Hillsdale County lies between the Wabash and Fort Wayne moraines. 

 Its southern portion is on the west side of St. Joseph River and its northern portion is west 

 of the headwater portion of Bean Creek. It lies mainly in southeastern Hillsdale County but 

 extends northeastward as a narrow strip a short distance into Lenawee County. It continues 

 between these two moraines down the St. Joseph Valley into Indiana. The till is very clayey 

 and extends to considerable depth. 



An extensive till plain lies in the western half of Lenawee County on the east side of the 

 Fort Wayne moraine. Its width is 6 to 8 miles and it runs from the northern edge of the county 

 in a course west of south to the southwest corner. It continues into Ohio and widens southward 

 as indicated in the discussion of the Fort Wayne moraine. At the northern end, in south- 

 western Washtenaw County, it is cut off by interlocking ridges. This till tract has an undulating 

 surface, in places nearly as uneven as the bordering part of the Fort Wayne moraine. It is 

 composed very generally of a stiff clayey till. 



In western Washtenaw County there is a tract covering nearly 100 square miles in which 

 the surface is less definitely ridged than on the bordering morainic tracts to the east and west. 

 It has, however, several large gravel knolls or kames (see Ann Arbor folio and topographic 

 sheet) rising 75 to 100 feet or more above the general level, as well as numerous small knolls, 

 and an esker known as the Lima esker. Marshy basins lie on the interfiuvial tracts, and narrow 

 strips of marsh border nearly all the streams. The surface is therefore far from flat and can 

 be called a plain only when contrasted with the neighboring ridges, whose surfaces are a 

 succession of steep hills and ridges. Owing to the loose texture of the drift the roads in dry 

 seasons work into loose sand. The drift contains many small stones 3 to 6 inches in diameter 

 that are apparently scattered through it rather than arranged in definite beds. Bowlders are 

 not rare on any part of the surface and are especially numerous in narrow strips winch may 

 properly be termed bowlder belts. One of these (see Ann Arbor folio) leads entirely across the 

 plain from the vicinity of Dexter southwestward to the vicinity of Pleasant Lake, passing near 

 the east end of the Lima esker and running past some prominent kames south of Lima Center. 



In northern Washtenaw County strips of till alternate with gravel plains that lead north- 

 westward toward the Huron Valley. The till is as a rule thickly strewn with bowlders, but its 

 surface- is comparatively smooth. It ranges from a clayey to a very loose textured deposit. 



