Abstract

The well-documented and dated post-Twocreekan drift (classical Valders Till) of the Green Bay–Fox River-Lake Winnebago lowland is traced to an interlobate junction with the Lake Michigan Lobe that overrode the Valders type locality. Additional support for the post-Twocreekan age of the surface drift between Valders and Two Creeks comes in part from geomorphic evidence of drainage from Later Lake Oshkosh into Glacial Lake Shoto between Manitowoc and Two Rivers.

The key new data and reinterpretations include: (1) a radiocarbon-dated site demonstrating that the surface till of the Green Bay Lobe there is post-Twocreekan, (2) the correlation of that site to the Brillion esker only 500 m northeast and at the same elevation, (3) the correlation of the stratigraphy and morphologic forms of those two localities to an interlobate moraine, (4) the recognition of the interlobate character of the moraine by the amount and structure of lacustrine and fluvial sediments to the crest of that moraine which required ice on both sides simultaneously, (5) the relationships of the drainage of post-Twocreekan Later Lake Oshkosh to Twocreekan wood and to the upper level of Glacial Lake Shoto, (6) the equivalent level of post-Twocreekan Glacial Lake Shoto to the (1 believe) erroneously interpreted pre-Twocreekan Glen-wood Stage of Glacial Lake Chicago, and (7) other details of the stratigraphy and morphology of the drift that support the thesis outlined above.

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