THE ORIGIN AND DEPOSITIONAL ENVIRONMENT OF THE HAYTON FORMATION - A NEWLY DEFINED LITHOSTRATIGRAPHIC UNIT IN EAST CENTRAL WISCONSIN

The Hayton Formation is present in the subsurface in much of east central Wisconsin. The sediments were deposited by ice, meltwater, and aolian processes associated with ice of the Green Bay and Lake Michigan Lobes, or an earlier undivided ice lobe that advanced from the north. Diamicton of the Cato Falls Member is easily distinguished in the field by its grayish color (5YR 6/1 to 10YR 4/6), cohesive and very dense matrix, abundant carbonate, silty matrix (37% sand, 44% silt, and 15% clay), and abundant well rounded, polished and striated clasts. North-south ice flow is indicated by bedrock striations, clast fabric, and drumlin orientation. Clast wear and bedrock abrasion indicate a high degree of comminution and a basal till origin. Matrix color and texture may be due to incorporation of the Maquoketa Shale as ice-flow was likely subparallel to the former outcrop or subcrop of the shale.

The gray silt and fine sand of the High Cliff Member is interpreted to be primarily aolian in origin. Regionally the High Cliff Member is a thin (generally less than 1 m thick) discontinuous drape over the Hayton till. It was likely deposited by wind near the retreating ice margin. Locally the gray silt and fine sand may have been deposited in water or slumped into shallow ponds. Plant remains have been observed dispersed in the gray silt and fine sand at several locations. The plant remains include leaves, stems, mosses, and twigs, and indicate a tundra environment. At the type section of the High Cliff Member, the plants are radiocarbon dated at 13,370 +/- 90 B.P. Commonly the gray silt and fine sand is interbedded with the base of overlying reddish brown tills of the Kewaunee Formation.

The Hayton Formation was likely deposited during the late Wisconsin, approximately 21,000 to 13,400 RCYBP. There are no radiocarbon dates to determine the beginning of the glacial advance or advances that deposited the till, and some of the till may have been deposited before the late Wisconsin.