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Geography Chap 12 (Goh Cheng Leong + NCERT)


Chapter  12

The Oceans

--International Council for the Exploration of sea. ===does reserch/ funding.

Ocean Relief


1)The continental shelf:
  >Formation = 1)Sea level ↑  2)Wave Erosion  3) Deposition.



  >Wider the shelf===less slope.
  >Mountainous region==Like that of Andes==No shelf is possible.
  >Transportation:
     >>continental shelf=limited depth + gentle slope= Height of Tide ↑ .
     >>makes Port construction difficult===Ships can leave/enter during Tides.
     >>Yet some of worlds greatest port are in continental shelf=London + Rotterdam, Hong kong and Singapore.
     >>Ports in Western coast
> Eastern coast.
       >>> West coast=Deep=non deltaic river+ coast of submergence , Except Malabar coast.
       >>> East Coast=shallow shelf= sediment by river+ Coast of Emergant.

  >Life= shallow +Light = Phytoplankton= Fishing ground.

2)The continental Slope = at the edge of continental shelf==it forms angle.

3)Deep sea plain:
  >AKA  Abyssal plain.
  >Appearance= undulating + several structure (= ridges+ trench +plain + plateau + island etc).

4)Trenches:= near continent= especially in pacific= Mariana trench @ Guam Island.

3 types of Oceanic Deposits
1)Mud =Terrigenous deposit= from Land= blue/Green/Red @chemicals= on Continental shelf mainly.

2)Oozes= Pelagic deposits= from “Skeleton/ shell”= calcareous remains.

3) Clays= mainly “Red clay”= vocanic dust=in ocean floor= abundant in pacific.

Salinity of Ocean
--Salinity distribution map= Isohalines.
--
Salts=NaCL 70% + Mg +K +Ca etc = same in proportion across ocean even in depth= Different concentration.
-- Lake Van
= highest Salinity @ 330parts of salt per thousand parts of water (Avg =35.2 per 1000).
--Factors:
  >Rate of evaporation
  >fresh water added.
  >connection with ocean.


Temperature of Ocean water

  

--Temp beyond 2000 fathom= constant approx.
--bottom temp always > Freezing point.


The Movement of Ocean Current:
1)Planetary wind= most dominant factor== ex- North of Indian ocean -- Ocean current changes with  Monsoon wind.

2)Temperature 

3)Salinity

4)Earth's Rotation.

5)Land




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