Ocean Basin Definition
Ocean basins can be defined as saucer-like depressions in the seabed of the earth’s surface. They differ in size from comparatively minor features of the continental margin to huge structural divisions of the deep sea basin. The largest ocean basins are about 3 to 5 kilometers deep and extend from the outer margins of the continents to the mid-ocean ridges.
Ocean basins cover about 71% of Earth's surface or approximately 361 million square kilometers (140 million square miles). Their average depth is 16,000 feet, and the total volume is approximately 1.35 billion cubic kilometers (322 million cubic miles).
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Divisions of the World Ocean
There are 5 major subdivisions of the world ocean. The five ocean basins are as follows:
The Pacific Ocean
Atlantic Ocean
Indian Ocean
Arctic Ocean
Southern Ocean
Pacific Ocean Basin
The Pacific Ocean contains more than half of its free water. In the area, this demonstrates about 155 million square kilometers. Comparatively, the area of Alaska, Hawaii, and the continental United States is about 4 million square miles, sixteen times less in surface area. All the continents could be accommodated into the Pacific basin.
The key characteristics of the oldest existing ocean basin have been shaped by the phenomena linked with plate tectonics. The coastal shelf that stretches to depths of about 600 feet, is narrow along North and South America, but is comparatively wide along Asia and Australia.
Under extreme pressure, the continental plates fold into mountain ranges and the oceanic plates are imposed downward, developing deep trenches known as subduction zones. The stresses at these regions of subduction are accountable for the volcanoes and earthquakes which give the Pacific basin the name "Ring of Fire."
Atlantic Ocean Basin
The second largest of Earth's 5 oceans, the Atlantic Ocean is most massively travelled, and the most rigorously studied, primarily due to its significance in ship traffic between Europe and North America. This ocean's name is extracted from Atlas, one of the Titans of Greek mythologies.
The Atlantic Ocean holds about 20% of Earth's surface, demonstrating about 75 million square kilometers. This takes into account the marginal seas: the Black Sea, Baltic Sea, Caribbean Sea, Denmark Strait, and Davis Strait, part of the Drake Passage, Mediterranean Sea, North Sea, Norwegian Sea, Gulf of Mexico and almost all of the Scotia Sea.
The Atlantic Ocean basin formation happened during the Jurassic period, about 150 million years ago, when a rift opened up in the supercontinent of Gondwana, causing the separation of South America and Africa.
Indian Ocean Basin
The third largest of Earth’s five oceans, the Indian Ocean is bounded on the west by Africa, on the east by Australia, on the north by Asia and Australasian islands. It occupies a total area of 68 million square kilometers. No natural boundary separates the Indian Ocean from the Atlantic Ocean, but a line around 4,020 kilometers long, linking Cape Agulhas at the southern end of Africa with Antarctica, is usually considered to be the boundary.
Southern Ocean
Though not a true ocean basin, it stretches on the north from the coast of Antarctica to 60° South latitude that coincides with the Antarctic Treaty Limit. The Southern Ocean is now the fourth largest of the earth's five oceans. The Southern Ocean consists of a special distinction of being a huge circumpolar body of water completely circumscribing the continent of Antarctica. It has an area of 20 million square kilometers and includes the Amundsen Sea, Bellingshausen Sea, Ross Sea, Weddell Sea a small part of the Scotia Sea, and part of the Drake Passage.
Arctic Ocean Basin
The smallest of Earth's five ocean basins has a total surface area including major subdivisions— the Norwegian Sea, the North Sea, the North Polar Sea and the Barents Sea—is approximately 14 million square kilometers.
The average depth of the Arctic Ocean is about 4,900 feet while the deepest point in the Arctic Ocean is about 17,880 feet.
Fun Facts
The ocean basins cover the largest area of the surface of the earth
Due to plate tectonics, but most oceanic lithosphere finally is subducted. Hence, the only existing oceanic lithosphere is younger than Jurassic in age and happens at locations farthest from the oceanic spreading centers.
Apart from areas where magmatism is strong enough to build volcanic structures above sea level, most of the oceanic magmatism are tough to access.
FAQs on Ocean Basin
1. What is an ocean basin?
An ocean basin is a very large, bowl-shaped depression on the Earth's surface that holds the water of an ocean. These basins are primarily formed by oceanic crust, which is thinner and denser than the continental crust that makes up the landmasses.
2. What are the major ocean basins of the world?
The Earth has five major ocean basins, which are ranked by size:
- The Pacific Ocean Basin (the largest and deepest)
- The Atlantic Ocean Basin
- The Indian Ocean Basin
- The Southern Ocean Basin
- The Arctic Ocean Basin (the smallest and shallowest)
3. How are ocean basins formed?
Ocean basins are mainly formed through the process of plate tectonics. At divergent boundaries, tectonic plates move apart, allowing magma from the Earth's mantle to rise and create new oceanic crust. This process, known as seafloor spreading, gradually forms the vast, deep basins that hold our oceans.
4. What are the main features you would find on an ocean basin floor?
The floor of an ocean basin is not flat; it has a varied landscape with several key features, including:
- Continental Shelf: The shallow, submerged edge of a continent.
- Continental Slope: A steep drop-off from the shelf to the deep ocean floor.
- Abyssal Plain: The vast, flat, and deep area of the ocean floor.
- Mid-Oceanic Ridges: Underwater mountain ranges where new ocean floor is created.
- Oceanic Trenches: The deepest parts of the ocean, formed where one tectonic plate is forced under another.
5. What is the main difference between an ocean basin and a sea?
The main difference lies in their scale and enclosure. An ocean basin is a massive geological feature that contains an entire ocean. A sea, on the other hand, is a smaller body of saltwater that is often partially enclosed by land, like the Mediterranean Sea or the Caribbean Sea. Seas are typically considered parts of the larger oceans.
6. Which is the largest and oldest ocean basin, and why is it significant?
The Pacific Ocean is the largest and oldest ocean basin on Earth. It is so large that it covers about one-third of the planet's surface. Its significance comes from its immense size, which plays a crucial role in regulating global climate and weather patterns. Being the oldest, its floor contains rock formations that provide valuable information about Earth's geological history.
7. Why is the Pacific Ocean basin often called the 'Ring of Fire'?
The Pacific Ocean basin is called the 'Ring of Fire' because its edges are lined with a high concentration of active volcanoes and frequent earthquakes. This intense geological activity is caused by the movement and collision of tectonic plates in areas known as subduction zones all around the Pacific rim.
8. What is the deep ocean basin?
The deep ocean basin refers to the part of the ocean floor that lies beyond the continental margin (the continental shelf and slope). It generally starts at a depth of about 2,000 metres and includes the vast abyssal plains, underwater mountains (seamounts), and the extremely deep oceanic trenches.
