SAGINAW LOBE. 151 



of the plain appears to be more rapid directly away from the moraine southward than along 

 the moraine westward, though it is rather rapid in the latter direction. 



Wells, reported to be through sand and gravel, have penetrated the highest part of the 

 gravel plain near Lexington and Mongo, Ind., to depths of 70 or 80 feet before reaching the 

 water table. At White Pigeon, Mich., fine sandy gravel was found to a depth of 140 feet, and 

 at Sturgis the waterworks wells appear to have been through gravel and sand to a depth of 

 140 feet. So far as can be learned all the material is loose or uncemented and seems likely 

 to have been deposited in the Wisconsin stage of glaciation and perhaps in large part imme- 

 diately preceding and accompanying the development of the Sturgis moraine. 



The topography along the south border of the Sturgis moraine is more diversified on the 

 west side of the St. Joseph Valley than it is on the east side. In the vicinity of Fabius are 

 characteristic outwash features in the form of a pitted gravel plain. South of this, in southern 

 Fabius and northern Constantine townships, St. Joseph County, are sandy undulating tracts 

 whose structure is what might be expected in an outwash apron, but whose surface is more 

 rolling than in the ordinary outwash apron; they include knolls as well as basins, but show 

 few bowlders or coarse pebbles. West of this for a few miles in the eastern edge of Cass County 

 there is no definite outwash, the moraine being bordered by a gently undulating till tract. 

 But in southwestern Newberg Township sandy drift sets in along the south border of the moraine 

 and extends west past Vandalia to the gravel plain that borders the Kalamazoo morainic 

 system of the Lake Michigan lobe. This sandy district, which includes several lakes and is 

 much interrupted by basins and marshes, may have been produced during the retreat of the 

 ice across it instead of as an outwash from the Sturgis moraine. The same is true of the undu- 

 lating sandy tract in Constantine and Fabius townships. The outwash on the east side of the 

 moraine of the Lake Michigan lobe in sees. 3 and 10, Fabius Township, and sec. 34, Flowerfield 

 Township, seems to have been deposited among stagnant parts of the ice sheet, for it is 

 interrupted by many basins. 



The strips of gravel plain between the constituent ridges of the Sturgis moraine in south- 

 eastern St. Joseph and southwestern Branch counties have rapid variations from coarse to 

 fine material, some portions being cobbly while . others near by are sandy. On the whole, 

 however, the sandiness increases from Branch County northwestward toward the St. Joseph 

 Valley through southeastern St. Joseph County along the course of discharge of the glacial 

 waters. The gravel plains that extend up into the transition belt in western Branch Countv 

 have a moderately coarse gravel with perhaps less admixture of sand than the plain with which 

 they connect in eastern St. Joseph County. At the eastern or headward ends, however, the 

 material seems to have been somewhat irregularly and indefinitely assorted by stream action. 

 In places it is difficult to determine where the gravel has its head, the passage from the till 

 into the gravel being apparently gradual rather than abrupt. 



INNER BORDER. 



Attention has already been directed to the gradual change from moraine to till plain and 

 to the extension of morainic spurs back into the till plain to the inner border of the Sturgis 

 moraine (p. 147). In southeastern Kalamazoo and southwestern Calhoun counties an area 

 of about 100 square miles is composed of clayey till and has a gently undulating surface, knolls 

 10 to 20 feet high being numerous. It is strewn with bowlders liberally but not so heavily 

 as the bordering moraines. This till tract is limited by the Tekonsha moraine on the north- 

 east, by the Sturgis moraine near Mendon on the southwest, by a gravel plain known as Climax 

 Prairie (formed in connection with the Tekonsha moraine) on the north, and by the great gravel 

 plain of the St. Joseph River valley on the south. 



South of the St. Joseph plain, in northern and central Branch County, an undulating 

 till tract similar to that north of the gravel plain is traversed by Coldwater River from 

 Coldwater to Union City. West of the Coldwater the tract is interspersed with the till ridges 

 and knolls of the transition belt already discussed (p. 147). East of the river the tract has a 

 gently undulating surface with few noteworthy knolls. 



