Continental shelf
Submerged edge of a continent, rich in life and resources.
Last updated
The continental shelf is the shallow seafloor, generally less than 200 m in water depth, that surrounds continents and islands.[1] Continental shelves cover about 27 million km², equal to about 7% of the ocean surface area.[1][2] The continental shelf begins at the shoreface and continues until the gradient increases markedly at what is termed the shelf break.[1][3]
Quick Facts
- Average width
- about 80 km (50 mi)
- Average slope
- about 0.5°
- Sediment accumulation rate
- 15–40 cm (0.492–1.31 ft) per millennium
- Global primary productivity support
- 15–20%
Facts from the source article.
Key facts and history
The continental slope below the break is much steeper, averaging 3°, and is often cut with submarine canyons whose formation was not well understood until the 1960s.[4] The Blue Habitats account notes that the shelf break was digitised manually at a nominal spatial scale of 1:500,000 using 10 m, 50 m and 100 m contours.[1] Continental shelves are most commonly classified on the basis of geomorphology or tidal range.[1] The Blue Habitats classification shows that medium-relief shelf (10–50 m vertical relief) covers the greatest area at 14,447,690 km².[1]
At the peak of the last ice age, the area of shallow continental shelf where benthic photosynthesis is possible was approximately 80% less than its present extent.[1] The shelf break occurs at a depth that is typically around 140 m, a consistency thought to result from lower sea levels during glacial periods.[5] The Siberian Shelf, located in the Arctic Ocean, is the broadest continental shelf, reaching a width of 1500 km.[6] Continental shelves have an average width of roughly 80 km.[6]
What the research sources say
The Blue Habitats account states that the continental shelf is geologically similar to the rest of the continent, with a foundation of granitic crustal material.[1] On tectonically active margins associated with subduction zones, shelf widths are commonly less than 20 km.[1] The Blue Habitats account explains that the major controls on shelf morphology include tectonic setting, sea level history, glaciation, and sediment supply.[1] Along passive plate boundaries, shelf sediments are commonly characterised more by biogenic sediments than by terrigenous sediments supplied by rivers.[1]
The Blue Habitats account notes that the broadest continental shelves are found on passive, trailing continental margins associated with wave erosion and limited sediment input.[1] The Arctic shelf has a greater fraction of low-relief shelf (45.1%) than any other ocean region, while the Antarctic shelf has the highest fraction of high-relief shelf at 69.3%.[1]
References
- Continental shelf – Blue Habitats. facts only, no text reused. bluehabitats.org
- Wikipedia, "Continental shelf" (CC BY-SA 4.0), which cites: Continental shelf – Blue Habitats (we also read that source) en.wikipedia.org
- Wikipedia, "Continental shelf" (CC BY-SA 4.0), which cites: Encyclopædia Britannica (original not read by us) en.wikipedia.org
- Wikipedia, "Continental shelf" (CC BY-SA 4.0), which cites: Pinet 2003, p. 39; Gross 1972, p. 45 (original not read by us) en.wikipedia.org
- Wikipedia, "Continental shelf" (CC BY-SA 4.0), which cites: Gross 1972, p. 45 (original not read by us) en.wikipedia.org
- Wikipedia, "Continental shelf" (CC BY-SA 4.0), which cites: Pinet 2003, p. 39; Pinet 2003, p. 39 (original not read by us) en.wikipedia.org
Each numbered sentence above was checked against the source it cites before publication. Sentences citing Wikipedia adapt text from the English Wikipedia article Continental shelf (contributors), used under CC BY-SA 4.0; this entry is available under the same licence. Other sources were used for facts only; no text or images are copied from them.
More in Geology And Landforms
Sources
Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.
- Wikipedia: Continental shelf (CC BY-SA 4.0).
- Word definitions: the , each quoted from its Wikipedia article.
Spotted an error? Know more?
Reader corrections go straight into our review queue. Suggest an edit · How this site is sourced