Abyssal plains are generally flat areas of the ocean basin, that are usually found at depths of 13,000-16,000 ft. Abyssal plains are believed to be flat because they are overlaid with sediments that have been drained off the surface of continents for thousands of years. On the abyssal plains, the sediment layers have hidden any deviation that may exist in the rock of the ocean floor under them. In the Atlantic and Indian Oceans the abyssal plains are usually bigger in length compare to those found in the Pacific Ocean.