Abstract
On November 18, 1929, an earthquake shook the New England coast and the Maritime Provinces of Canada. This earthquake, known as the Grand Banks Earthquake, loosened a large mass of mud on the edge of the continental shelf. The mud then slid down the continental slope into the deeper part of the North Atlantic Ocean. It eventually spread over the abyssal plain at the foot of the slope, parts traveling over 500 miles. One might think that a mass of loose mud flowing in the ocean would quickly mix with the sea water and lose its integrity as a separate unit, but this is not the case. The mud has a greater density than sea water because it is a combination of water and an abundance of heavier rocks, sand, silt, and clay particles. This heavier mud flows beneath the lighter sea water somewhat like water flows on land beneath lighter air. Only a small amount of mixing takes place between the mud and the overlying water. Such an underwater mudflow is called a turbidity current, and the new mud layer deposited as the flow stops is referred to as a turbidite.