Geography Chap 10 (Goh Cheng Leong + NCERT)

Chapter  10

Coastal Landform




By Erosion  and   by Deposition

The action of= Waves + Tides +Current + Storms:
--All brings changes= coastal lansforms.
--Waves = a little damage to shoreline + beech building.
--Storms= 10 X pressure of normal waves…brings changes =cliff, building etc.
--Tides= In creases/dec the territory of wave action.
--Current=erosion= silt/material etc.

The Mechanism of Marine erosion:
--When “height of wave” < depth of water = Shallow water.
--When wave encounters= shallow surface= breaks and curves forward or refracts as per surface alignment.
--Swash= water that (after encountering shallow surface) rushes beach with=debris etc.
--Backwash = Opp of Swash.
--Undertow= beeech pe jab paani pair kheechti hai.

Erosion Type:
1)Corrosion= waves armed with debris erodes.

2) Attrition= debris in wave= continuously collides with each other.

3) Hydraulic action=Splash on surface with crack= air trapped---pressure ↑.

4) Solvent action= chemical weathering===only  in Limestone beach..

Coastal features by erosion:

Cape and bays:
--where hardrocks= especially @ alternate hardrock + soft (Granite + limestone).
--caused by Waves.
--Larger structure = Bay of bangal/ Persial gulf ===due to Submergence or earth movement.
--(Image ↓):



Cliffs and wave-cut platforms:
--steep mountain near shore.
--depends or geological factores = orientation of bed(Layer of rock structure).
--if “cliff bed”= seawards =will erode more= dislodge into sea.
--if “cliff bed”=Landwards= less resistive.
--(Image↓):



--Notch formation =at the base of cliff:
--Rock cut platform as shown in below diagram ===when increases in length==erosion becomes negligible.
--Image ↓ || for video link click here…
 

Cave, Arches, Stack and Stump
--Caves= water splashes forms it.
--Arches= two caves merges to form arches.
--Stack= upper portion of cave eroded= Pillar.
--Stump=Pillar(stack) height reduced after erosion==only small surface visible above surface.
--(Image ↓):

Geos and Gloups:
--Blow-holes AKA Gloups(because of the sound made by water in its formation).
Water splashing the Cave compresses air inside=== which may vent out forming= Blow-Holes
--Image ↓:



--Geos = blow holes and Cave = which were earlier joined by inside tunnel= comes to surface.
--Image ↓:

Coastal feature of Deposition

1)Beaches
--Finer material = closer to sea….>backwash= usually carry only finer.
--In upland region= where high land abruptly meets sea===short coast=Chilean coast.

2)Spits and bars:
--Check the video link for description.
--Image ↓:

3)Marine dunes and dune belt
--Normal sand dunes
--ex-South west France,Belgium,Netherland etc
--Image ↓


2 Types of Coast:
--(IMAGE ↓):: J



1)Coastlines of Submergence:
-- Ria Coast:
   >Ice age ends=== sea level ↑.
   >Discordant/Transverse Mountains = at right angle to flow ==== so that sea water doesn’t splashes to form erosional structure  .
   >Gentle sloped…………
   >Tributaries= frequently dendritic structure observe= old river trajectory.
   >Location= N-W France + N-W Spain + S-W Ireland etc (MAP)
   >Not Good for communication.
   >Image ↓:

--Fiord coast:
   >Formed by Glacial action -----U-Shaped
   >Steep slope = often rising straight from sea.
   >Tributaries= often joining at right angle.
   >economy= ports + settlement = difficult= rare.
   >Location = High altitude of “Temperate region”.
                     =Norway + Alaska + British Columbia + S. Chile +South island of New Zealand.
   >Not good for communication.
   >Image ↓:



--Dalmatian Coast:
  >Concordant coast= Mountain runs Parallel to coast.
  >submergence produces= chain of Island parallel to coast flow.
  >parallel Island= earlier crest of valley having river= Now Submerged.
  >Location = Adriatic sea coast ; San Francisco in Pacific. + Island of Sumatra with the Mentawai Islands strongly parallel in the Indian Ocean
  >Not good for communication.
  >Image ↓:

--Estuarine coast:
  >Submerged lowland===mouth of the river drowned(Submerged)è forming Estuaries.
  >ex- :
         >>East= Godavri + Krishna + Pennar + Cauvery
         >>West= Narmada + Tapti
--For understanding concept of Etuary....click here and here also
>Image ↓ :

2) Coastline of Emergence
--Uplifted lowland coast:
  >Upliftment of continental shelf=  water level becomes shallow.
  >Laggon + salt marshes(=swamps(forested area of lowlying land, near river having stagnant water) without trees=marshes) and mud flats= common.
  >Image ↓:


--Emergent upland:
 >Straight + steep =cliffs
 >Deep offshore water = unlike uplifted==because coastline has not rised = but land has uplifted.
 >by tectonic activity + fault
 >Location= Western ports of Deccan + Western Arabian Coast facing read sea.
 >Good for Port.
 >Image ↓