Geography Chap 6 (Goh Cheng Leong + NCERT)

Chapter 6

Ice Age and Types of Ice Masses

--Ice Age= Pleistone period(30 KYA)>>>>> covered temperate zone.
--Glacier= flow of Ice/water from ice cap>>>large ice cap under weight melts.
--Neve/fern=climate where seasonally ice melts>>>throught year melting +freezing makes the structure very hard and hold the ground===this structure so formed= Neve.
--When ice flows= max velocity in middle of profile==erodes material.
--Impact of Neve:
   >water coming out of neve= has lots of loads already= less vertical eroding power = wide + shallow river
   >but in placed with heavy rainfall= V-Shaped valley is seen.

some features:
Karevas:
--Karewas are lacustrine deposits [deposits in lake] in the Valley of Kashmir 
--Subsequently, due to endogenetic forces, the Baramullah Gorge was created and the lake was drained through this gorge.
--The deposits left in the process are known as karewas.
--karewas are mainly devoted to the cultivation of saffron, almond, walnut, apple and orchards.

Glaciers in Himalya:
--Karakoram Range:
   > Siachen Glacier= Largest outside polar-sub polar region. =in Nubra valley.
   >Fedchenko Glacier=2^nd Largest outside P-S region= at Pamirs.
   >Hispar Glacier=3^rd largest outside P-S region= tributary of Hunza river.

--Pir panjal Glacier:
   >small + less compared to Karakoram.
   >Sonapani = Chandra Valley in Lahul region.

--Kumaon-Garhwal region:
   >Gangotri= Ganga river originates.

Mineral in Himalya:
--Geosynclinical deposits in tertiary rocks(the time of Himalya formation) are regions of potential coal and oil reserves.
--Coal is found in Kashmir
-- Copper, lead, zinc, gold, silver, limestone, semi-precious and precious stones occur at some places in the Himalayas.
--excavation is difficult.

Landforms of Highland Glaciation:
--In highland= erosion takes place >>>>> deposition= lowland
--Glacier erodes by 2 process:
    >Plucking= water into cracks>>> freezes to break material.
    >Abrasion=materials plucked>>> scratches the surfaces.
--Intensity of Abrasion = Velocity  + load +shape of material+ temp + geological structure of valley.

Glaciated Highland’s Fearures:

1) Corrie, Crique or cwm:
--repeated digging activity of “Neve”>>> makes U shaped landform= Corried,crique.
--(Image ↓):

2)Aretes and Pyramidal peaks:
--Aretes=2 Corries cut back to form---Knife dege ridege.
--Pyramidal peaks= Corries from 3 side.= Matterhorn Switzerland.

3) Bergschrund:
--specially during Summer.
--ice in “Corrie lake” melts >>> ice in the back(Steep side)= makes several verticlle cracks(because no smooth flow as lower ice has melt in lake).
--This Vertical Cracks= Bergschrund (Image ↓):

4)U shaped glacial trough:
--Normal Valley has “inter-locking pattern”(for detail go to  "the middle of valley course"...click here)

(image interlock valley ↓)


--flow of glacier flow to valley(during ice age) was joined by ice from “Corries”.
--This high momentum blunted the “inter locking pattern”
--Forming= U-Shaped glacial trough = which now= U shaped valley= Ribbon lake.

5)Hanging Valley:
--in above U-shaped case=== the valley made by tributaries glacier from “Corrie” = Hanging Valleys.
--Hangs above the main valley(ribbon lake)>>> bcoz main valley erodes more(more load).
--Forms natural head of “Hydro powerplant”.
(Image of 4+5 both ↓)



6)Rock basin and Rock steps:
--in U-Shapped Valley
--A glacier erodes and excavate the bedrock in an irregular manner.
-- The unequal excavation gives rise to many rock basins later filled by lakes in the valley trough where a tributary valley joins the main valley,
-- the extra weight of the ice in the main valley cuts deeper into the floor of the valley at the point of convergence forming a rock step.
-- A series of such rock steps may also be formed due to different degrees of resistance to glacial erosion of the bedrocks.

7)Moraines:
--Made from pieces of rocks= in the glacier.
--Brought down to Valley accumulates as shown in Image bleow ↓:

--identification:
   >When Glacier melt>>> moraines(in ice, falls) are depsited at snout(terminal edge).
   >Since glacier ice melts back by stages and not simultaneously >>> series of mound of “Moraine”.
   > moraines sometime meets sea-----if glacier flows into it.
(Image ↓)

Landforms of Glaciated low Land:
--Mainly depositional landform.
--Deposition occurs from =1)Glacial flow  2)Ice sheet
--Ice sheet is more prominent…..glacial flow mainly in highland or some restricted area for deposition.

land forms:
1)Roche Mountonnee
--When glacial flow faces a gentle mountain.
--it creates upstream abrasion
--Down stream =Plucking.
--image ↓



2)Crag and Tail
--When glacial flow faces a steep mountain.
--it creates upstream abrasion = forming steep.===depositing another side.
--Down stream =deposition >>>gentle slope.
--(Image ↓)

3)Boulder clay or glacial till
--unsorted glacial deposits.
--fertility depends on compostion.
--Ex- Northern-West mid of USA,
--(Image ↓):

4)Erratics:
--Boulders of varying size.
--used to trace the source and direction of ice flow.
--(Image ↓):

5)Drumlin:
--Composed of = Boulder clay. >>> Elongation= in direction of flow.
--Topograbhy=like, basket of egg.
--Ex- Northern Ireland.
--(Image ↓):

6)Eskers:
--composed of= sand + gravel (sub glacial melt)
--Height=less = 200 feet
--length= can be very long= several miles.
--since they are porus>>>water passes across>>> less or no trees.
--(Image ↓):   

                    

7)Terminal moraines:
--coarse debris at the edge of ice sheet.

8)Outwash plains:
--plain formed of glacial sediments deposited by meltwater outwash at the terminus of a glacier.
-- meltwater at the snout of the glacier deposits its load of sediment over the outwash plain, with larger boulders being deposited near the terminal moraine, and smaller particles travelling further.

These Landforms can be favorable or unfavorable….. depends:
--Relief + deposition/erosion+ intensity of glaciations etc