MORAINIC SYSTEMS AT HEADS OF LAKE MICHIGAN AND SAGINAW BASINS. 193 



of a small north tributary of Grand River and is less continuous than in the swampy channel 

 to the north. Much of it is only 10 or 15 feet high, but in the. middle part of its course it attains 

 a height of about 40 feet. At the southern end it divides into a network of ridges which incloses 

 basins. Opposite its south end, on the south side of Grand River, a gravelly plain containing 

 basins and standing 15 to 30 feet above the stream may prove to be a delta or fan connected 

 with it. 



The third or northern section is in a swampy depression in the headwaters of Willow Creek 

 in" the northeast part of Onondaga Township. The swamp extends from the north line of the 

 township southward along the border of sees. 1 and 2, 11, and 12, into sec. 13. It is separated 

 from the swampy channel containing the middle section of the esker by an undulating tract 

 of sandy drift about half a mile wide. The esker is a low ridge, commonly but 15 to 20 feet high, 

 which winds back and forth across the line of sees. 11 and 12 in a general southward course. 

 A short parallel esker ridge lies in the southeast part of sec. 11. Near the southern ends of 

 these ridges lies a group of sharp kames 40 or 50 feet high and beyond these the gently undu- 

 lating tract just mentioned. The trough in which this esker lies is in the outer part of the 

 Charlotte morainic system and is bordered by a very bowldery, knob and basin morainic tract. 

 The middle section of the esker, ou the other hand, has its entire course through a gently undu- 

 lating tract such as separates the moraines of this region. 



The excavations in the Rives esker throughout its entire length show a large preponderance 

 of material of local derivation, Carboniferous sandstone being conspicuous and forming a °'reat 

 majority of the cobbles and coarser stones. This is interesting in view of the fact that the 

 surface bowlders of the border districts are very largely granitic rocks of distant derivation. 

 The stream which formed the esker appears therefore to have derived its material from very 

 near the base of the ice sheet. A similar condition has been noted in many other eskers in Michi- 

 gan and neighboring States. 



The swampy depression along the line of the esker was probably not excavated in a single 

 tunnel, for in many places it is one-fourth mile or more in width. It is more probable that the 

 subglacial stream shifted back and forth, carrying away the englacial material which would 

 otherwise have gone to fill this depression. The depressions or esker troughs antedate the esker 

 ridges, the ridges being the last feature produced before the disappearance of the ice. 



The kames associated with parts of the esker seem likely to have been closely connected 

 with it in origin and to have been developed by the concentration of material in openings in 

 the ice. The material in the kames, like that in the eskers, is largely local, indicating that it 

 came from the basal portion of the ice sheet. 



WALTON ESKER CHAIN. 



The Walton esker chain lies in Walton Township, Eaton County, a few miles southwest of 

 Charlotte, along the borders of the Battle Creek valley. Its northern end is in sees. 2 and 3, 

 Walton Township, just south of a swamp which bears westward from Battle Creek toward 

 Olivet station and which seems to have been a fine of glacial drainage that comes back to the 

 Battle Creek valley south of the station. The present valley of the creek is very narrow and 

 seems hardly adequate to have carried the glacial drainage. 



A complex network of ridges 5 to 15 feet high, among which are basins and level gravelly 

 tracts, forms the head or northern end of the esker in sees. 2, 3, 10, and 11. The ridges lead 

 into sec. 15, to what seems to be an esker delta or fan-shaped plain that stands about 40 feet 

 above the creek, the whole constituting the northern and probably the youngest section of the 

 esker chain. The delta plain lies south of the Battle Creek valley and extends nearly a mile 

 west from the intersection of Big and Battle creeks ; it contains basins 20 feet deep but other- 

 wise is nearly level. 



The second section of the chain consists of a sharp gravel ridge 30 to 40 feet high which 

 leads south from the southwest part of sec. 15 and which is bordered on each side by narrow 

 swampy depressions. This leads into a fan-shaped expansion, with nearly level surface, which 

 34407°— 15 13 



