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Oceanography is the study of the ocean’s physical, chemical, and biological features, as well as the ocean’s ancient history, current state, and future....

Oceanography is the study of the ocean’s physical, chemical, and biological features, as well as the ocean’s ancient history, current state, and future.

  • Oceanography is the science of oceans, as the name implies.
  • Oceanography encompasses all studies conducted on or connected to oceans, from history to current climatic variations; chemistry to biological processes to products; origin to destruction; pollution to conservation.
  • It is a branch of science that examines the physical, ecological, geomorphic, and dynamic properties of oceans.

The ocean floor may be divided into three major divisions based on depth as well as relief. Three major divisions are:

  • Continental Margin
  • Deep-Sea basin or Abyssal plain
  • Mid Ocean ridges
Continental margin:

The continental margin lies between the continents’ shores and deep-sea basins. It includes:

  • Continental shelf
  • Continental slope
  • Continental rise
  • Deep Ocean trenches
Continental shelf:
  • It is an extended margin of each continent occupied by shallow seawater. The continental shelf ends with a very steep slope called the shelf break.
  • The width of the continental shelf varies from ocean to ocean and continent to continent, but the average width is approx 80 km.
  • There is narrow shelf width along with Chile’s coast and the west coast of Sumatra and the largest shelf width having 1500 km is the Siberian shelf in the Arctic ocean.
  • The continent’s shelf is covered with various sediments of different periods that are brought by rivers, glaciers, and winds from land and distributes by waves and currents.
  • Massive sediments are received over longer times from the continent and become the sources of fossil fuels.
Continental slope:
  • The Continental slope lies between the continental shelf and the ocean basin. It starts with the steep slope of the continental shelf. The Continental slope boundary indicates the end of continents.
  • Canyons and trenches are found in this region.
Continental rise:
  • Continental rise lies between the continental slope and the abyssal plains. It is made up of sediments that come from the continental shelf.
Oceanic Deeps or ocean trenches:
  • It is the deepest part of the ocean characterized by steep sides and narrow basins.
  • It is generally 3-5 km deeper than the surrounding ocean floor.
  • It is found near the Islands arc associated with Volcanos.
Deep-sea basin or Abyssal plains:
  • It is extensive plains that lie between the continental margin and mid-oceanic ridges.
  • Some fined grains sediments such as clay and silt from the continental margin also get accumulat in these areas.
Mid-Oceanic ridges:
  • The mid-ocean ridge consists of two ranges of mountains separated by a large trough( depression). It is an interconnected series of mountain systems within the ocean. The peaks of mountain ranges can be so high that they even reach above the surface of the sea. Iceland is part of the Mid-Atlantic Ridge.
  • It is a feature of the central rift system called the crest. Intense volcanic activity occurs in rift systems at the summit.
Bottom Topography of the Atlantic ocean:
  • Mid-Atlantic Ridge
  • Seamounts and islands
  • Trenches
  • Continental Shelf
  • Coral Island
  • Abyssal plain
Temperature and Density of Ocean Water
  • Massive meteorology, which deals with the portion of the atmosphere that overspreads the huge water masses, is concerned with the study of ocean temperatures.
  • The density of a substance is defined as its mass per unit volume expressed in grams per cubic centimeter.
  • The term density is commonly used to refer to specific gravity, which is defined as the ratio of density to that of distilled water at a certain temperature and pressure.
  • At 4 degrees Celsius, pure water has a maximum density of one unit, however, the density of the sea varies depending on the salinity content.
  • Pure water’s density is only determins by temperature and pressure.
  • Seawater, on the other hand, is affects by temperature, pressure, and salinity.
Ocean Salinity
  1. Salinity is defined as the total amount of solid material in a kilogramme of seawater express in parts per thousand.
  2. The salinity of saltwater is 3.5 per cent on average, measured in parts per thousand.
  3. Salinity fluctuates due to winds caused by changes in air pressure.


Read More : Tectonic Plates

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