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What kinds of sediments usually cover continental shelves?
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continental shelf
The broad, gentle pitch of the continental shelf gives way to the relatively steep continental slope. The more gradual transition to the abyssal plain is a sediment-filled region called the continental rise. The continental shelf, slope, and rise are collectively called the continental margin.
The composition of sediments covering continental shelves is determined by a complex interplay of tectonic setting, river input, and wave energy. Because these environments are dynamic, they are often described as "palimpsests," where new layers of sediment are deposited over older, reworked materials.1
Common types of shelf sediments include:
- Quartz Sands: These dominate shelves along high-energy coasts or those adjacent to mountainous regions where rivers deliver significant clastic material.1
- Carbonate Sediments: Shelves that are isolated from continental clastic input—such as those near the Bahamas or western Florida—are often covered by carbonate materials.1
- Muddy Deposits: In areas where large rivers drain vast continental regions, the supply of sediment may be sufficient to keep pace with sea-level rise, leading to the accumulation of mud across the shelf surface.1
- Erosional Debris: Shelves located on tectonically active margins, such as those along the Pacific Ocean, tend to be steeper and covered by a thin layer of erosional debris.1
Fine-grained materials are frequently winnowed out by wave energy and storm-driven currents, often being transported into estuaries or beyond the shelf break.1