MOKAINIC SYSTEMS AT HEADS OF LAKE MICHIGAN AND SAGINAW BASINS. 187 



mile from the highest point in the southern peninsula, on the farm of Albert Miller, sec. 11, 

 T. 20 N., R. 9 W., at an altitude of 1,580 feet, was sunk 337 feet without striking rock. 



No means have as yet been found for determining how much of this great mass of drift is 

 referable to the Wisconsin and how much to preceding stages of glaciation. The convergence 

 of the ice lobes and the comparatively small removal by glacial drainage favored a large accu- 

 mulation of drift, and the amount deposited at the last ice invasion may be as great as the 

 relief of the ridges, or an average of about 300 feet. 



COMPOSITION. 



The surface portion of the drift, particularly in the northern part of the morainic tract, 

 presents interesting alternations of gravelly or sandy drift with a somewhat clayey drift. In 

 the southern part the sharp ridges and knolls are largely of gravel and sand and the gently 

 undulating tracts are chiefly of till. Till is in some places only a thin veneer over thick deposits 

 of gravel and sand; this is especially noticeable in the district southwest of Hastings, where 

 wells have been sunk to 150 to 200 feet entirely through sand and gravel except 10 to 20 feet 

 of clayey material at the surface. The variations in structure can perhaps be best described 

 from south to north, in the direction of ice retreat and the order of development of the morainic 

 tract. 



In Barry Comity, southwest of Hastings in the vicinity of the iunction of the outer moraine 

 of the Kalamazoo system and its correlative of the Saginaw lobe, the moraine is chiefly of sand 

 and gravel with a thin veneer of bowldery till. In places, especially east of Gun Lake and south 

 of the bend of Thornapple River below Hastings, the surface is sandy. From Hastings directly 

 northwestward to Grand Rapids the drift appears to be entirely from the Saginaw lobe and is 

 chiefly clayey till. Some surface sand appears along the borders of Thornapple River. In the 

 bend of the river north of Grand Rapids sand and gravel lie along the immediate edge of the 

 valley, but a stiff clayey till is found farther back. The moraine on the north side of Grand 

 River west of Grand Rapids was produced by the Lake Michigan lobe and is also largely of till 

 with more or less sand near the edge of the Grand and Rouge river valleys. In the northern 

 part of Kent County, from the Grand Rapids & Indiana Railway west to Rouge River and also 

 for 2 to 4 miles east of the railroad, the drift is largely gravelly and sandy, but farther east it is 

 prevail ingly clayey till. 



Considerable clayey till occurs in the part of Montcalm County south of Tamarack Creek 

 in a district covered by the Saginaw lobe. Gravelly drift appears, however, over an area of 

 perhaps 50 square miles on the west side of Flat River in northern Montcalm County, much of 

 which is sharply ridged. The smoother tracts to the north are about equally divided between 

 clayey and sandy drift. 



A prominent ridge formed by the Lake Michigan lobe in the southeast part of Newaygo 

 County has clayey till on its western slope but is gravelly and sandy on its crest and eastern 

 slope. The morainic system in eastern Newaygo County north of Muskegon River is very 

 largely of sandy and gravelly drift, but is of clayey drift over about 10 square miles in the north- 

 east corner of the county in the eastern part of Barton Township. This clayey drift extends 

 eastward to the Muskegon Valley hi Mecosta County north of Big Rapids, and northward in a 

 strip several miles wide along the line of Lake and Osceola counties to the vicinity of Leroy 

 in western Osceola County. West of it hi Lake and Newaygo counties there is an elevated 

 range of gravelly and sandy hills. 



In Mecosta County the district between the Muskegon and Little Muskegon valleys carries 

 a succession of clayey and sandy strips trending nearly east to west. In the southwestern 

 part of the county a clay strip about 5 miles wide running westward from Altona past Borland 

 lies immediately back of the large outwash apron developed by the Saginaw lobe and is appar- 

 ently the product of the Saginaw lobe. North of this clayey tract, in the northern half of 

 Austin Township and south of the line from Byers to Rodney, a very sandy morainic tract 4 to 

 6 miles wide stands higher than the till tracts on either side. Immediately southeast of Big 

 Rapids a till tract has its northern border near the line of the Pere Marquette Railroad between 



