The continental shelf is the extended margin of each continent occupied by relatively shallow seas and gulfs. It is the shallowest part of the ocean showing an average gradient of 1° or even less. The shelf typically ends at a very steep slope, called the shelf break.
The continental shelves are covered with variable thicknesses of sediments brought down by rivers, glaciers, wind, from the land and distributed by waves and currents. Massive sedimentary deposits received over a long time by the continent shelves, become the source of fossil fuels.
Their shallowness enables sunlight to penetrate through the water, which encourages the growth of plants and organism ,now rich in plankton, fishes thrive on them, so continental shelves are richest fishing grounds. Example: Grand banks of new foundland, The north sea and the sunda shelf. Their limited depth and gentle slope keep out cold under-currents and increase the height of tide. This sometimes hinders shipping and other marine activities since ships can only enter and leave port on the tide.