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U.S. Geological Survey Scientific Investigations Map 2784

Quaternary Geologic Map of Connecticut and Long Island Sound Basin

Prepared in cooperation with the State of Connecticut Department of Environmental Protection, Geological and Natural History Survey

Published 2005
Version 1.0

Janet Radway Stone, John P. Schafer, Elizabeth Haley London, Mary L. DiGiacomo-Cohen, Ralph S. Lewis, and Woodrow B. Thompson


The Quaternary geologic map (sheet 1) and explanatory figures and cross sections (sheet 2) portray the geologic features formed in Connecticut during the Quaternary Period, which includes the Pleistocene (glacial) and Holocene (postglacial) Epochs. The Quaternary Period has been a time of development of many details of the landscape and of all the surficial deposits. At least twice in the late Pleistocene, continental ice sheets swept across Connecticut. Their effects are of pervasive importance to the present occupants of the land.

The Quaternary geologic map illustrates the geologic history and the distribution of depositional environments during the emplacement of glacial and postglacial surficial deposits and the landforms resulting from those events.

Photograph of Meigs Point

Westerly view of the Hammonasset-Ledyard moraine as it disappears offshore beneath Long Island Sound at Meigs Point, Hammonasset Beach State Park in Madison, Conn. Photograph by Janet Radway Stone.


U.S. Geological Survey Scientific Investigations Map 2784 consists of two map sheets and a text pamphlet. These are provided in Adobe PDF format. Right-click (PC) or control-click (Macintosh) to download the files to disk.

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Obtaining the Printed Map

This map can be purchased from the USGS Store.


For scientific questions or comments concerning this report, contact Janet Radway Stone.

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