The continental shelf is the extended margin of each continent occupied by relatively shallow seas and gulfs. It is the shallowest part of the ocean showing an average gradient of 1° or even less.
The width of continental selves depend on two factors:-
- If there is a high mountain, closer to and parallel to the coast near the ocean than continental shelves will be narrow. Example– Pacific Continental Shelf(only 16 Kms) along Andes Mountain in South America.
- When wide plains are along the coast than the shelves will be wider. Example – North America (East Coast) – 96-120Km.
Origin
There are multiple theories for origin of Continental Shelves:-
- Formed due to subsidence of continental Coasts due to rising thermal convective shells beneath the Earth.
- Due to prolong Detritus deposition by rivers near the coast (generally formed in Calm Oceans/Seas).
- Faulting of Continental blocks due to Tectonic activities.
- Fall in sea level either due to glaciation or subsidence of oceanic floors.
- Bending/tilting of continental plate towards ocean due to Tectonic activities.
- Marine Erosion by Ocean Currents and fluvial deposition brought by rivers.
- Due to formation of wave cut platforms.
Continental Shelf Relief Features
- Submergence of boundaries of the continent,
- Erosional work of the waves
- Extension of land from the sediments deposited by rivers
Characterstics of Continental Shelf
- There is no clear or well-defined line separating oceans from the continent. In fact, continents do not end abruptly at the shoreline.
- They slope seaward from coast to a point where the slope becomes very steep.
- This shallow submerged extension of the continent is called as the Continental Shelf.
- The depth usually ranges from 120 to 370 meters from the surface water.
- Their width also varies from a few kilometers to more than 100 kilometers.
- This variation can be seen even in the context of the Indian peninsula. The continental shelf of the western coast of India is much wider than that of the eastern coast. (Note: NIOS text mentions the opposite case)
- Continental shelves are much narrow or absent in some continents, particularly where Fold Mountains run parallel or close to the coast.
- The shallow water over the shelf enables sunlight to penetrate through the water to the bottom and encourages the growth of microscopic plants and animals called planktons, which are the food for fishes.
- Continental Shelves are of greater importance to man. They are the sources of fishes, minerals including sand and gravel, etc.
- A large quantity of world’s petroleum and natural gas are obtained from the shelves.
- Coral reefs are also common on continental shelves.
- One of the striking features of the continental shelf is the presence of submarine canyons which extend to the continental slope.
- These canyons are ‘steep-sided valleys’ cut into the floor of the seas.
- They are very similar to the gorges found on the continents.
- One of the reasons for the formation of the submarine canyon is the underwater landslide.
- The continental shelf is generally considered to be territorial water extents of the nations to which it adjoins.
FAQs on Continental Shelf
Ques 1. What is the continental shelf?
Answer: The continental shelf is a gently sloping underwater extension of a continent, located between the shoreline and the deeper ocean. It is characterized by shallow waters and forms an integral part of the continental margin.
Ques 2. How is the continental shelf formed?
Answer: The continental shelf is primarily formed through processes such as sediment deposition from rivers, glacial erosion, and sea-level changes over geological time. As the continents were shaped by various natural forces, the continental shelf emerged as a submerged part of the land.
Ques 3. What is the significance of the continental shelf?
Answer: The continental shelf is of great importance economically and ecologically. Its shallow waters are rich in marine life, supporting diverse ecosystems and providing valuable fishing grounds. Moreover, the continental shelf is vital for offshore oil and gas exploration as it contains valuable natural resources beneath its seabed. Additionally, it plays a crucial role in coastal protection by acting as a buffer zone against storm surges and erosion.
Continental Shelf of The Ocean
Read Also : Bottom Relief Features Of The Ocean
