The drift and the lobes: the ground the ice left

~14,000–13,000 years before present · THE GEOLOGICAL RECORD AT COUNTY STRENGTH

Three lobes of the last ice sheet made this ground, and the prairie is the floor of the lake their meltwater left. At the strength of the geological record for the Kankakee country: as the ice retreated some 14,000 years ago, meltwater from three lobes — the Lake Michigan lobe, the Saginaw lobe and the Huron-Erie lobe — ponded and spread across the lowland south of the Valparaiso Moraine, laying down the outwash that became glacial Lake Kankakee. The lake drained about 13,000 years ago, breaching at the Momence Ledge, and left behind it the Grand Kankakee Marsh and a plain of sand and outwash. Terre Coupee sits at the eastern end of that outwash plain, compressed between the Valparaiso Moraine — the great ridge the Lake Michigan lobe built at its stand — and the till plain of the Saginaw lobe to the east: the town's hill is the plain's edge, and the prairie's famous level ("almost as level as a barn floor") is a lake floor's level, which is why the 1878 telling's shallow lake is not a metaphor but a memory of the ground's own making. The named members of this ground, then: the Kankakee outwash plain itself, the Valparaiso and Kalamazoo moraines standing over it, and the lake plain of glacial Lake Kankakee beneath the town. What this article cannot print is the site figure: the drift's thickness at Township 38 North, Range 1 West stands in the Indiana Geological Survey's county record, unreached by this section, and it is the article's named residue — the lobes and the lake are carried whole; the borehole number is the settler's to give.

Sources:

1. The glacial record of the Kankakee basin as dug for this run (the geological literature of glacial Lake Kankakee: the three lobes, the Valparaiso and Kalamazoo moraines, the Momence Ledge drainage, ~14,000–13,000 YBP) — printed at county strength.
2. Chapman (1880), pp. 337 and 765 — Terre Coupee "at one time covered by water"; the prairie's level and measure.
3. The residue: the Indiana Geological Survey's record for T38N R1W (drift thickness), named and unreached.