Chapter 6: OCEANOGRAPHY
Ocean crust isn't
uniform or flat. It has higher diversity than continental
It is highly
dense, thick crust and basaltic.
Oceanic crust is
created at the mid ocean ridge and destroyed at the Trench.
The ocean floor is divided into three main regions:
plains / Abyssal plains
This is the seaward extension of the continent from the shoreline to the continental edge. They are absent on mountainous coasts and are widest in shores of lowland coasts. The continental shelf formation may be by submerging of continental edges due to rising water levels or by water erosion. Alternately they could have been formed by deposition of silt from rivers.
- They are responsible for preventing cold under current from rising and also increase the height of tides.
- They are excellent location for ports.
- The sunlight reaches the shelves and so minute plankton grows on them. This causes fishes to reach the shelves. The shelves are thus known as the richest fishing grounds of the world.
shallow part of ocean and connected to the continent.
has highest bio diversity.
the bottom and hence aquatic plants are found.
land are also found.
Resources in continental shelf:
petroleum reserves are found in shelves. E.g.: Persian
Gulf, Strait of Hormuz, Arctic Ocean, and Gulf of Mexico.
metal rarely found on land but is abundant in continental
shelf due to marine volcanism.
heavy metals on shelf. E.g.: Monazite sand [thorium],
gold, silver and diamonds.
at the end of the shelf.
form canyons, underwater waterfalls.
Transition between ocean
block and continental block.
trenches as trenches consume the depositional material of the
of the ocean floor.
in types of landforms and deposits from continental and aquatic
Ocean trenches: These are long, narrow deeps that penetrate to about 30000 feet at times. They are usually located near continents. Pacific Ocean has the deepest trenches.
Resources from an abyssal plain:
nodules are a concentration of metals around a core. Found
in all oceans. Some of the minerals are rare on land.
UN Convention on laws of seas:
sea mining, environment protection, maritime boundary and
the convention, territorial sea is 12 miles from coast, 24 miles
is contiguous zone and 200 miles is the exclusive economic zone
where state can explore minerals and produce energy.
Fig 2: UN Laws of the Sea
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