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How did the Laurentide Ice Sheet shape Long Island’s landscape?

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glacier Perito Moreno Glacier, Los Glaciares National Park, Argentina.

The Laurentide Ice Sheet played a fundamental role in shaping the landscape of Long Island. The island is framed by two major terminal moraines—the Harbor Hill and Ronkonkama Moraines—which consist of till and outwash sand deposited at the glacier's margins between 22,000 and 18,000 years ago.1

These glacial sediments were later reworked by stream and coastal processes, eventually forming the sandy barrier islands located off Long Island’s south shore.1