The World’s Ocean Basins

In the last unit, you were introduced to the ocean basins:  The Pacific, Atlantic, Indian and Arctic.

Although each of these ocean basins is connected to create one world ocean, each basin is unique to create very distinct bodies of water. They vary based on their physical, chemical and biological properties. For instance, the temperature, chemical composition and types of living organisms are different for each basin.

The Pacific Basin contains about half of the earth’s water and has the greatest surface area of all of the ocean basins (179.7 x 106 km<sup>2</sup>). The Pacific Basin is also the deepest of the basins with an average depth of 4,282 meters (15,215 ft). The Pacific Ocean contains about 25,000 islands which is a number greater than all of the other oceans combined.

Day 17.1

The name Pacific comes from the Latin name Mare Pacificum which means “peaceful sea”. However, the Pacific is often subject to rough waters caused by typhoons, earthquakes and tsunamis. The theories of plate tectonics suggest that the Pacific basin may be shrinking. The water temperature of the Pacific ranges from freezing to about 29oC. The Andesite Line is an important point in the Pacific basin. It distinguishes the Central Pacific Trough from the rest of the ocean basin. Deep troughs, volcanic mountains and volcanic islands are found in the Central Pacific. In the Pacific Basin you will find the Pacific Ring of Fire, the Great Barrier Reef and the Mariana Trench.

The Atlantic Basin is the second largest ocean basin with a surface area of 106.4 x 106 km2 and an average depth of 3,926 meters (12,881 feet). Puerto Rico Trench is the deepest point in the Atlantic Ocean. The name Atlantic is derived from Greek mythology and means the “Sea of Atlas”. The most significant characteristic of the Atlantic Ocean is the submerged mountain range known as the Mid-Atlantic Ridge. It extends from Iceland down to about 58o S Latitude. It is at this location that a large portion of sea floor spreading occurs. In addition to the Mid-Atlantic ridge, the Atlantic Ocean Basin consists of the South Sandwich Trench, the Romanche Furrow and many abyssal plains.

Day 17.2

The Atlantic is thought to be the saltiest of the oceans, with the average salinity ranging between 33 – 37 parts per thousand. Tides in the southern Atlantic are semi-diurnal; meaning there are two high tides and two low tides each day. The water temperature ranges from -20C to 29oC. In the Atlantic, you will find the Bermuda Triangle, the Gulf Stream, trade winds and plenty of annual hurricanes.

The Indian Basin covers about 20% of the Earth’s water surface and has an average depth of 3,963 meters and surface area of 74 x 106 km<sup>2</sup>. It is separated from the Atlantic Ocean by the 20º east meridian and from the Pacific by the 147º east meridian. The Indian Ocean includes the Red Sea and the Persian Gulf. The deepest point in the Indian Ocean is the Java Trench. The African, Indian and Antarctic plates converge in the Indian Ocean. The climate and the currents are strongly influenced by monsoon wind systems.

Day 17.3

The Arctic Basin is the shallowest of the four basins with an average depth of 1,205 meters (3,953 ft). The deepest point in the Arctic Ocean is the Eurasia Basin.