Geology

Sea floor

The Gulf of Maine was formed by glaciers pushing debris down from the Appalachian Mountains. When the glaciers retreated some 11,500 years ago, they left behind scoured bedrock and towering moraines. These are now the basins and banks that give the Gulf of Maine its distinctive shape. For more information please see A Geologic History of the Gulf of Maine.

Because of its relative youth, the Gulf of Maine has a tremendous variety of bottom habitats, from the soft, flocculent muds that are beginning to accumulate in the deep basins to the unsorted coarse gravel of the banks to areas of scoured bedrock. This great variety of habitats supports a large variety of benthic organisms and provides habitat and protection to the developing stages of numerous pelagic and demersal species. For more information on these benthic habitats and the technology used to map them please see our Substrate Page. The World Wildlife Foundation and the Conservation Law Foundation have been developing habitat classification maps designed to capture the fundamental environmental conditions that influence ecological patterns and processes. For a description of these maps see Seascapes.

Much of the legendary productivity of the Gulf of Maine can be credited to its unique shape and bathymetry. The banks and basins interact with the strong tidal currents and coastal currents to create water habitats with all the right elements to support extraordinary productivity. For more detailed descriptions of these banks and basins please see Physioregions. For depth statistics and graphics of the Gulf of Maine see Bathymetry.

Just as islands can support unique biodiversity that has evolved in isolation from other terrestrial communities, seamounts are islands of high productivity and unique biodiversity in an otherwise low-productivity region of ocean. The Gulf of Maine area is home to such a chain of seamounts. Called the New England Seamounts, this chain of extinct volcanoes extends more than 1000 km from the southern edge of Georges Bank eastward into the Atlantic Ocean. See Seamounts for more information.