Geological Setting of Long Island Sound

The diversity of marine life inhabiting Long Island Sound is due, in part, to the dynamic nature of the landscape. The advancing Wisconsin age glacier (26,000-21,500 years ago), with subsequent erosion of the coastal plain, shaped the underlying geology of the region. Tidal dynamics and inputs from rivers continue to shape the underwater landscape today. The shape of the basin and variations in the distribution of sediments in Long Island Sound dictate how different species and communities are distributed. With an average depth of only 65 feet, the tidal mixing of fresh and oceanic waters creates conditions favorable for the high productivity of organisms in this estuary.

The seafloor of Long Island Sound is as varied in sediment type as the coast that surrounds it. Basin sediments range from boulders and cobble to sand and mud. Combinations of these sediment types abound in many areas of the Sound. Click on the image below to view a map of sediment types and distributions on the Sound seafloor.

Click here for more information on the geology of Long Island Sound.