190 PLEISTOCENE OF INDIANA AND MICHIGAN. 



CHARACTER. 



In western Barry County, where this morainic belt connects with the Kalamazoo system, 

 knob and basin topography prevails, sharp knobs rising 50 to 100 feet above the surface of the 

 numerous lakes inclosed in basins. Southeastward the lakes become more scattered, but knob 

 and basin topography continues along much of the moraine. Not a few of the knobs rise 

 abruptly 50 to 60 feet, but these are interspersed with many low knolls 20 feet or less in height. 

 In the vicinity of the Battle Creek valley marshy tracts of considerable extent are inclosed by 

 sharp sandy knolls, some of which are 60 feet or more in height. Wanandager Creek crosses 

 the moraine through a swampy plain. Knolls 60 feet or more in height are numerous along the 

 east side of Battle Creek as far north as Olivet. In eastern Calhoun and western Jackson 

 counties a few knolls are 50 or 60 feet high, but the great majority reach only 15 or 20 feet. 

 Swampy east-west valleys that traverse the district are thought to have carried the border 

 drainage to Kalamazoo River. Some of them are occupied by Rice Creek and its tributaries, 

 but others are not traversed by streams at the present day. Narrow strips of nearly plane 

 gravelly land alternate with the morainic strips. Many of the plains are pitted and appear to be 

 outwash aprons formed on the front of the receding ice border. Near the mouth of Sandstone 

 Creek, in northwestern Jackson County, knolls fronting on the Grand River valley rise abruptly 

 80 to 100 feet above the valley bottom, but farther south the moraine is smoother. To the 

 east, in Rives Township, knolls 40 to 60 feet in height rise abruptly from swampy tracts, and an 

 esker leads southward from Rives Junction nearly to the city of Jackson. 



The sharp morainic belt leading from Jackson eastward along the south side of Portage 

 Swamp contains knobs 75 to 100 feet or more in height which stand near the south border of the 

 range. An undulating strip a mile or more in width extends from the base of these knobs down 

 to the border of the swamp. 



North of the Portage Swamp knolls are found only in clusters or small detached areas sur- 

 rounded by nearly plane tracts of sandy drift which rise northward into a later morainic system, 

 the Charlotte. These are probably correlatives of better-defined morainic belts in northwestern 

 Jackson County. 



STRUCTURE OF THE DRIFT. 



COMPOSITION. 



On the whole, the drift of this morainic system is of rather sandy texture. It tends to grade 

 into clayey till toward the inner or north border, especially in Barry and Eaton counties. In 

 Calhoun and Jackson counties, where the underlying rock is sandstone, the till is generally sandy. 



BOWLDERS. 



Bowlders are found in great numbers along much of the southern edge of the moraine from 

 Barry County to Washtenaw County. They are least conspicuous in the vicinity of the Battle 

 Creek valley, where the drift is exceptionally sandy. Bowlders are also found some distance 

 back from the border in belts, many of which are traceable for several miles. In central and 

 western Jackson County, as in districts to the south where sandstone hills are present, small sur- 

 face bowlders are remarkably numerous — so numerous, indeed, that fences miles in length are 

 built of them. Many of them are only a foot or two in diameter. The great majority are of 

 granitic rock and are rounded by exf ohation. The bowlders appear to be much more numerous 

 on the surface than beneath it; their numbers are rarely troublesome in well borings even 

 where the surface is thickly strewn. 



In the vicinity of the reentrant angle in Barry County bowlder belts trend north-northeast 

 and south-southwest, the direction corresponding pretty closely to that of the ridges of the Lake 

 Michigan part of the Kalamazoo system. East of this reentrant angle, however, the bowlder 

 belts trend north-northwest and east-southeast, conforming to the direction of the Saginaw 

 part of the Kalamazoo system. 



