How can a muddy current rush downhill beneath the ocean?

An underwater slope can carry a fast-moving mixture of water and sediment. Because suspended sand and mud add mass, the mixture can be denser than the surrounding clearer seawater. Gravity can then drive it downslope.

This sediment-rich flow is called a turbidity current. A slope failure or other disturbance may start it. As it moves, turbulence can keep particles suspended and the current can pick up additional sediment from the seabed.

The moving mixture can erode channels and carry material far from its starting point. If the current slows enough, particles begin to settle. Larger or heavier grains often settle before finer material.

Repeated currents help build layered deposits and reshape parts of the seafloor. They are different from a surface wave traveling across the ocean: a dense, particle-laden flow is moving along the bottom. The ocean can therefore transport a large amount of land-derived material through processes hidden beneath its surface.