What is the sedimentary bed deposited by turbidity currents called?

• A. Well-Sorted Sediment
• B. Aphotic Zone
• C. Silt
• D. Turbidite

Answer: (D)

Turbidity currents move dense, particle-rich water downslope and when they slow, the sediment settles out to form a graded bed. This specific type of sedimentary bed is called a turbidite. The graded nature—coarser material at the bottom, finer material above—reflects the decreasing energy of the flow as it dissipates. Turbidites are common on continental margins and can be stacked in sequences (Bouma sequences) as successive turbidity events occur. The other terms don’t name the bed: well-sorted sediment describes uniform grain sizes, the aphotic zone is a depth-related light term, and silt is a grain size, not the deposit name.