<P> The continental shelf is an underwater landmass which extends from a continent, resulting in an area of relatively shallow water known as a shelf sea . Much of the shelves were exposed during glacial periods and interglacial periods . </P> <P> The shelf surrounding an island is known as an insular shelf . </P> <P> The continental margin, between the continental shelf and the abyssal plain, comprises a steep continental slope followed by the flatter continental rise . Sediment from the continent above cascades down the slope and accumulates as a pile of sediment at the base of the slope, called the continental rise . Extending as far as 500 km (310 mi) from the slope, it consists of thick sediments deposited by turbidity currents from the shelf and slope . The continental rise's gradient is intermediate between the slope and the shelf . </P> <P> Under the United Nations Convention on the Law of the Sea, the name continental shelf was given a legal definition as the stretch of the seabed adjacent to the shores of a particular country to which it belongs . </P>

Lies at the base of the continental slope