Marseilles moraine

It begins near Elgin, Illinois, and extends south and west of Chicago metropolitan area, turning eastward 30 miles (48 km) to 40 miles (64 km) south of the lake in Kankakee and Iroqouis counties, entering Indiana.

The glacier had been in retreat when it stopped for an extended period, depositing glacial till and sand creating the hills of the moraine.

This follows the east side of Fox River, past St. Charles, Geneva, Batavia, and Aurora.

It may end here, or its remnants may be obscured beneath the Lake Kankakee sand ridges.

The width of the " Iroquois " moraine is generally between 2 and 4 miles (3.2 and 6.4 km), but bouldery areas on its north border extend about 2 miles (3.2 km) farther north to the southern edge of an extensive sandy plain traversed by Kankakee River.

Between eastern Jasper County and Bass Lake, the area is generally sand covered, with a broad low ridge running from the north end of the Iroquois moraine at San Pierre to North Judson.

This ridge has patches of boulders in the till line from North Judson to Bass Lake, as do many other moraines in northern Indiana.

The majority of the crest is a series of swells seldom exceeding 20 feet (6.1 m)with easy slopes.

[2] Along Fox River, in Kane and Kendall counties, a belt of coarse gravel lines the outside of the Marseilles moraine.

The gravel is so extensive in Kane and Kendal counties and so small farther down Fox River as to suggest that it forms a delta.

[1] The basin now drained by the Iroquois River into the Kankakee was blocked by ice in that direction.

The outlet would have been west across the rim of the basin in northern Ford County into the east fork of Vermilion River.

Evidence of fine sand and silt covering the till plain show that a Lake Watseka occupied this part of the Iroquois valley.