Pg. 4 (fig. 3), 12 (fig. 6), 30 (fig. 8), 37, 38. Clarkson Till. Consists of silty to sandy and pebbly yellowish-brown to olive-gray mottled boulder clay in upper 37 feet and olive-gray to brownish-gray in lower 20 feet. At type locality underlies Loveland Formation and overlies Cedar Bluffs and Nickerson Tills (both new). No exposures known at present time. Fluviatile equivalent of Clarkson Till is believed to be Grafton Formation (new). Recognized in Nebraska. Age is middle Pleistocene (early Illinoian).
Type locality: ground water survey test hole A22-2-25dc, drilled in SW corner, sec. 25, T. 22 N., R. 2 E., Stanton Co., 8 mi north and 0.5 mi west of Clarkson.

Source: US geologic names lexicon (USGS Bull. 1350, p. 156-157).