The rocks surrounding the western half of Lake Superior dip to the southeast in Minnesota and northern Douglas County, Wisconsin, and dip more steeply northwestward in the limb extending southwestward from Keweenaw Point to Minnesota. As the main axis is not far north‐west of the outcrop of the south limb, the syncline is not symmetrical. Dips of 25 to 30 degrees are unusually high on the north limb; on the south limb dips vary from 30 to 90 degrees.

The purpose of this paper is to discuss briefly the major facts as they are now revealed to us in the rocks of this syncline and to construct a hypothesis correlating these major facts in its history. This hypothesis relates the origin of the various formations and their present structure to the intrusion of an enormous bathylith, whose final result is evident to us in the scores of thousands of . . .

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