A stream seeks the shortest path to the ocean. To do so it takes a new path. When the turbidity current reaches the continental rise it slows down and deposits material in a submarine fan. When the turbidity current slows down the coarser material, for example sand, settles out first, then finer material settles out with mud deposited near the top of the bed. The result is a graded bed.
Turbidity currents are erosive and can form submarine canyons on the continental slope.
Continental shelves are common all over the world. Fifteen percent of our continents are presently underwater. However during last maximum glaciation, about 20,000 years ago sea level was about 400 feet lower and 100 miles from its present location. The Hudson River cut the valley across the continental shelf while sea level was lower. This valley is now underwater and is known as the Hudson Canyon.