LATER MORAINES OF LAKE MICHIGAN, SAGINAW, AND HURON-ERIE LOBES. 249 



ESKERS. 

 BURIED MASON ESKER. 



The Mason esker attains its best development in the region south of this district, and that part 

 is described by Mr. Leverett. (See PL VIII, p. 208.) It reappears in full strength on the north 

 side of Cedar River in the southeast part of Lansing. A short distance north of the river it 

 appears to be overridden and partly buried under till. Both north and south of Michigan 

 Avenue the troughs on its sides are filled with till and its gravel ridge is nearly level with the 

 general surface. About a mile farther north, at Sheridan Street, it reappears in normal relations 

 as a gravel ridge 20 to 30 feet high and 100 to 200 feet wide, with swampy troughs on both sides. 

 About a mile to the north it heads in two or three short branches. 



On both sides of Michigan Avenue, where the esker troughs are filled with drift, large pits 

 were opened many years ago for gravel and sand. Most of the pit walls were old and covered with 

 talus at the time of the writer's visit, so that no good sections showing the structure of the 

 deeper parts were found. Sand is a large component throughout, but considerable coarse 

 material is present in the upper layers, and several crystalline bowlders and two or three large 

 blocks of much disintegrated bituminous coal were seen. The largest coal bowlders were 2 feet or 

 more in diameter and many smaller pieces occurred in the upper layers. The deeper parts, so 

 far as shown, appeared to consist of horizontally bedded sand of about the grade used for 

 making mortar. The upper layers were not so distinctly bedded. 



The front of the Lansing moraine runs toward the northeast through sees. 30 and 20, 

 Lansing Township, crosses to the north side of Grand River at the Logan Street Bridge, and 

 runs thence east through the southern part of the city, crossing the river again just below the 

 junction of Cedar River. West of the bridge it occupies both sides of the river, but in the city 

 it is not very strongly developed. It is somewhat stronger on the east side of the river between 

 the river and the esker. The trend of the moraine to this point carries it directly to the over- 

 ridden part of the Mason esker and it seems certain that it was the Lansing moraine that overrode 

 the esker ridge and filled the troughs on its sides. 



East of the buried section of the Mason esker a small flat plain about half a mile wide forms 

 a recess between the esker and a high morainic ridge to the northeast. This seems like a till 

 plain, but it originally carried many bowlders. The unmodified part of the esker, with its 

 lateral troughs running north from Sheridan Street, was probably formed at the time of the 

 Lansing moraine, for it shows no effects of overriding. It seems probable, therefore, that the 

 ice front rested on the flat plain east of the esker but deposited only bowlders at that place. 



Beds of laminated brick clays lie on both sides of Michigan Avenue, about 3 miles east of 

 the State capitol. On the north side, the clays are about 10 feet deep and though they appear 

 to contain no stones, they are contiguous to stony ground that suggests a thin overlying layer 

 of till. The time and circumstances of the deposition of this small body of lake clays were not 

 definitely determined, but probably they were laid down in a local lake formed south and east 

 of Lansing by an obstruction of the Lansing channel southwest of the city. (See p. 251.) If, 

 however, they are buried under stony till it is not clear whether the overriding was done by 

 the Lansing or by the Grand Ledge moraine, for the high moraine just back of the clays to the 

 northeast appears to belong to the Grand Ledge moraine rather than to the Lansing. 



The Mason esker seems to end in the southeast part of sec. 3, Lansing Township, and it 

 does not reappear farther north except in a few small fragments. The trough, however, which 

 runs northward in well-defined form as a swampy depression from sec. 34 to sec. 4, Dewitt 

 Township, contains several small knolls or ridges of gravel. North of Dewitt, in Olive Township, 

 an esker nearly a mile long, belonging to the time of the Portland moraine, runs north to south 

 in sees. 26 and 35. Thence northward the line of the esker is not continued by a definite trough 

 but is represented by a series of separate swamps lying between the morainic ridges and trending 

 a little east of north. 



