Abstract

Quaternary glacigenic deposits exposed along the Sandy River valley in New Sharon, Maine, are associated with ice-proximal deposition in a northeast-trending stream valley. Fine-grained sediments represent distal deposits by turbidite deposition, turbid sediment plumes, and associated ice-rafted debris in a proglacial lake. Coarse-grained deposits and stratified diamicton are ice-proximal sediments deposited by gravity-flow processes, subaqueous sediment discharge, and fluvial deposition. Massive diamicton was deposited by subaqueous sediment discharge or by subglacial processes.

In contrast to previous depositional models that call for multiple glaciations to reflect the various facies, the glacigenic sediments at New Sharon were deposited entirely during a single glacial cycle, the late Wisconsinan. Glacitectonic and petrofabric data reflect an upsection shift in deformation from a northeast to a northwest source, attributed to late Wisconsinan sublobes in the Sandy River and Kennebec River valleys. Ice in the Kennebec River valley dammed drainage in the northeast-oriented lower Sandy River valley, creating a proglacial lake into which both sublobes deposited and deformed proglacial sediments during the early late Wisconsinan. Mainphase Laurentide ice eventually merged with and overwhelmed the sublobes.

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