Jordan, Wilkinson and Georges Basins, each more than 600 feet (200 meters) deep, are the deepest habitats within the Gulf of Maine. Their great depths resulted from glacial erosion of relatively soft rocks. In the summer, the water of these basins becomes layered into warm, nutrient-poor surface water; cold, nutrient-rich intermediate water; and cool high-salinity bottom water. On the seafloor of these basins live unique marine communities, such as fields of " pens," primitive relatives of soft corals.