The soil of marine biomes varies from one type to another but usually includes muds, gravels, sands, silts, clays or oozes. The soil makeup depends on the distance of the sea floor to the nearest continental shelf and the ocean surface.
Coastal and continental shelf regions of the marine biome contain mostly terrigenous soil created from sedimentary, metamorphic or igneous rocks that have been eroded and weathered above the surface. Rivers, ice and wind transport the sediment to marine waters.
Turbidity currents, underwater avalanches, sweep much of the terrigenous sediments around coastal waters and continental shelves but not to the deepest abyssal region of the ocean. Only the finest terrigenous sediments make it to this region to become clays.
The microorganisms living near the surface of the ocean and near coastal regions are so small and light that when they die, their remains eventually fall to the abyssal ocean floor, where oozes are formed if at least 30 percent of the soil is biological.