The continental shelf is the extended underwater plain surrounding a continent, which gradually slopes down from the shoreline to the continental slope. The continental shelf typically extends about 75 to 100 miles from the shoreline, but in some places, it can extend up to 200 miles. The continental shelf is an essential part of the oceanic environment and has a significant impact on human life and the global economy.
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Formation of Continental Shelf
It is formed due to the erosion and sedimentation processes that took place over millions of years. The continental shelf is mainly composed of sedimentary rocks and sediments like sand, gravel, and mud. These sediments were transported by rivers and ocean currents, which deposited them on the continental shelf. Over time, the sediments accumulated and formed a layer that gradually increased the width of the continental shelves.
However, there are various theories that explain the formation of this feature.
- Plate Tectonics: This theory suggests that continental shelves were formed by the movement of tectonic plates. When two plates collide, one may be forced under the other, creating a deep ocean trench. Meanwhile, the other plate is pushed up, creating a shallower area around the continent.
- Eustasy: Eustasy refers to changes in global sea level. According to this theory, continental shelves were formed when sea levels fell during glacial periods. As the water receded, the continental margin was exposed, and rivers deposited sediment, eventually creating a broad, shallow shelf.
- Subsidence: This theory suggests that continental shelves were formed by the sinking of the continental crust due to geological processes like thermal cooling, compaction, or subsurface loading. As the continental crust subsides, it allows the shelf to form around it.
- Erosion and Deposition: This theory suggests that continental shelves were formed by the constant erosion of continental landmasses and the deposition of eroded material along the continental margins. Over time, these deposits accumulated to form the broad, shallow shelves we see today.
Overall, the formation of continental shelves is likely the result of a combination of these geological processes.
Comparison between the Continental Shelf and Deep-Sea Plain
| Feature | Continental Shelf | Deep-Sea Plain |
|---|---|---|
| Definition | Shallow underwater platform that extends from shoreline up to 200 nautical miles into the sea | Large, flat area of the deep ocean floor beyond the continental rise |
| Depth | Average depth of about 200 meters | Generally deeper than 2,000 meters |
| Distance from Shore | Extends from shoreline up to a distance of 200 nautical miles | Beyond the continental slope |
| Location | Found adjacent to continents and islands | Found in the deep ocean |
| Topography | Generally flat with gradual slope | Generally flat with no significant relief |
| Sediment Composition | Composed of sedimentary rocks | Composed of abyssal sediments |
| Ocean Life | Supports a rich diversity of marine life | Home to unique species adapted to extreme pressure and darkness |
| Human Exploitation | Exploitation of natural resources such as oil, gas and minerals, and fishery resources | Limited human activity due to harsh conditions, some scientific research and deep-sea mining possible in the future |
Role of Continental Shelf
It plays a critical role in the oceanic environment. It is a habitat for a vast number of marine organisms, including fish, crustaceans, and mollusks. The shallow waters of the continental shelf allow sunlight to penetrate, which provides energy for photosynthesis and supports the growth of phytoplankton, the base of the oceanic food chain. It also serves as an important fishing ground, providing a livelihood for millions of people around the world.
Economic Importance
It has immense economic importance. It is a significant source of oil, gas, and minerals like sand, gravel, and precious metals. The extraction of these resources contributes significantly to the global economy. The exploration and exploitation of these resources require sophisticated technology and expertise, which has led to the development of the offshore oil and gas industry.
Legal Framework Governing Continental Shelf
The legal framework governing the continental shelves is provided by the United Nations Convention on the Law of the Sea (UNCLOS). UNCLOS defines the rights and responsibilities of states regarding the use and management of the oceanic environment. It provides guidelines for the delimitation of maritime boundaries, including the continental shelf. UNCLOS also defines the rights of coastal states to explore and exploit the natural resources on the continental shelf.
Disputes
Disputes over the continental shelves are common, particularly in regions where the shelf overlaps with the maritime boundaries of multiple countries. The resolution of such disputes is governed by UNCLOS, which provides a framework for a peaceful resolution through negotiations or arbitration. However, some disputes remain unresolved, leading to tensions and even armed conflicts.
Environmental Concerns
This is vulnerable to environmental degradation due to human activities like oil and gas exploration, mining, and fishing. These activities can cause habitat destruction, pollution, and overfishing, leading to the loss of biodiversity and ecosystem services. The degradation of the continental shelf can have severe consequences for human communities that depend on its resources.
Continental Shelf in India
India has a coastline of approximately 7,500 kilometers and an Exclusive Economic Zone (EEZ) of about 2.02 million square kilometers. The continental shelf of India is a shallow, underwater platform that extends from the coastline up to a distance of 200 nautical miles (370 kilometers) into the sea.
According to the United Nations Convention on the Law of the Sea (UNCLOS), India has sovereign rights over the continental shelf, which includes the exploration and exploitation of natural resources such as oil and gas reserves, minerals, and fishery resources. India has been exploring its continental shelf for hydrocarbon reserves since the 1970s and has made several significant discoveries.
In 2015, India submitted a claim to the United Nations Commission on the Limits of the Continental Shelf (CLCS) to extend its continental shelf beyond 200 nautical miles into the Bay of Bengal and the Arabian Sea. The CLCS approved India’s claim in 2019, giving India an additional 1.5 million square kilometers of continental shelf.
Overall, India’s continental shelf holds significant potential for the country’s energy security and economic growth.
Continental shelf UPSC
This is an important topic in the UPSC exam as it is related to geography, international law, and India’s maritime security and economic interests. Here is some information about the continental shelf that may be useful for the UPSC exam:
- Definition: It is the underwater extension of a continent that slopes gently towards the ocean floor. It extends from the shore to a distance of 200 nautical miles or to the outer edge of the continental margin, whichever is farther.
- India’s Continental Shelf: India has a coastline of around 7,500 km and an Exclusive Economic Zone (EEZ) of about 2.02 million square km. The continental shelf of India extends up to 200 nautical miles from the coast and covers an area of about 0.52 million square km. India has sovereignty over its continental shelf and has the exclusive right to explore and exploit its natural resources.
- UNCLOS: The United Nations Convention on the Law of the Sea (UNCLOS) provides the legal framework for the delimitation of maritime boundaries and the exploitation of marine resources. India is a party to UNCLOS and has submitted its claim for an extended continental shelf beyond 200 nautical miles to the United Nations Commission on the Limits of the Continental Shelf (CLCS).
- Economic Significance: It is a potential source of hydrocarbons, minerals, and fisheries resources. India has been exploring its continental shelf for hydrocarbon reserves since the 1970s and has made several significant discoveries. The extension of the continental shelf will provide India with an additional area for resource exploration and exploitation.
- Maritime Security: It is also important for India’s maritime security as it provides a buffer zone between India’s coastline and the open ocean. The Indian Navy conducts regular patrols and surveillance in the continental shelf to deter illegal activities such as piracy, smuggling, and fishing.
Overall, this is an important topic for the UPSC exam as it is related to multiple aspects of India’s maritime interests.
Comparison between the Continental Shelf and Continental Slope
| Feature | Continental Shelf | Continental Slope |
|---|---|---|
| Definition | Shallow underwater platform that extends from shoreline up to 200 nautical miles into the sea | Steeply sloping transition between the continental shelf and the deep ocean floor |
| Depth | Average depth of about 200 meters | Can be as deep as 4,000 meters or more |
| Distance from Shore | Extends from shoreline up to a distance of 200 nautical miles | Begins at the edge of the continental shelf |
| Gradient | Gentle slope with an average gradient of about 1 degree | Steep slope with an average gradient of 4-5 degrees |
| Sediment Composition | Composed of sedimentary rocks | Composed of a mix of sedimentary and igneous rocks |
| Topography | Generally flat with gradual slope | Steep drop-off with canyons and gullies |
| Ocean Life | Supports a rich diversity of marine life | Diverse range of species adapted to different depths |
| Human Exploitation | Exploitation of natural resources such as oil, gas and minerals, and fishery resources | Limited human activity due to harsh conditions, some scientific research possible |
Summary
- It is a shallow, underwater platform that extends from the shoreline up to a distance of 200 nautical miles (370 kilometers) into the sea.
- It is composed of sedimentary rocks and has an average depth of about 200 meters.
- The It covers approximately 7% of the world’s ocean surface and supports a rich diversity of marine life.
- It is an important source of natural resources such as oil and gas reserves, minerals, and fishery resources.
- The United Nations Convention on the Law of the Sea (UNCLOS) provides the legal framework for the delimitation of maritime boundaries and the exploitation of marine resources, including the continental shelves.
- Countries have sovereign rights over the continental shelves and can explore and exploit its resources within their designated boundaries.
- The width of the continental shelves varies around the world, with some regions having broad, shallow shelves and others having narrow, steep shelves.
- It is an important buffer zone between the coast and the open ocean and helps protect the shoreline from storms and erosion.
- Climate change and sea level rise can impact it. The extent and characteristics of the continental shelves, as melting glaciers and ice sheets can increase the volume of water in the ocean and cause changes in ocean circulation patterns.
MCQ
Q. What is the distance up to which the continental shelf extends from the shoreline?
a. 500 nautical miles
b. 200 nautical miles
c. 50 nautical miles
d. 100 nautical miles
Answer: b. 200 nautical miles. It is a shallow, underwater platform that extends from the shoreline up to a distance of 200 nautical miles into the sea.
Q. What type of rocks are the continental shelves composed of?
a. Igneous rocks
b. Metamorphic rocks
c. Sedimentary rocks
d. Volcanic rocks
Answer: c. Sedimentary rocks. It is composed of sedimentary rocks and has an average depth of about 200 meters.
Q. What is the legal framework for the delimitation of maritime boundaries and the exploitation of marine resources, including the continental shelves?
a. United Nations Convention on the Law of the Sea (UNCLOS)
b. United Nations Framework Convention on Climate Change (UNFCCC)
c. United Nations Educational, Scientific and Cultural Organization (UNESCO)
d. United Nations Human Rights Council (UNHRC)
Answer: a. United Nations Convention on the Law of the Sea (UNCLOS). UNCLOS provides the legal framework for the delimitation of maritime boundaries and the exploitation of marine resources, including the continental shelves.
Q. What is the average depth of the continental shelves?
a. 100 meters
b. 500 meters
c. 200 meters
d. 1000 meters
Answer: c. 200 meters. It has an average depth of about 200 meters.
Q. Why is the continental shelf an important buffer zone between the coast and the open ocean?
a. It supports a rich diversity of marine life
b. It helps protect the shoreline from storms and erosion
c. It is a potential source of natural resources such as oil and gas reserves
d. It provides a pathway for ocean currents
Answer: b. It helps protect the shoreline from storms and erosion. It is an important buffer zone between the coast and the open ocean and helps protect the shoreline from storms and erosion.
Explanation: These questions cover basic concepts related to the continental shelves, including their extent, composition, legal framework, depth, and importance. The answers and explanations are provided to help students better understand the topic and prepare for the exam.
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