Glaciers Erosional and depositional landforms

1. Module – 5
Landforms
Associated with
Glacial Action.
SELMANUL FARIS

2. • Glacier Action.
• Types of Glaciers.
• Erosional and Depositional
landforms

4. Glacier
 A glacier is a moving mass of ice.
 It can be considered a river of ice.
 But the velocity of movement in a glacier is lesser than in a river.
 The movement of glacier is very slow.
 The movement could be a few centimetres to a few metres a day or
even less or more. Glaciers move basically because of the force of
gravity.
 Movement in the ice is possible in relatively flat areas also.

5.  In fact the glaciers can move even in an up-slope direction
 This is possible because the movement of ground ice is caused not
only by the gravitational force but also by the compressive force of
the overlying mass.
 Glaciers originate in areas where most of the precipitation occurs in
the form of snowfall.
 Polar ice caps and high mountain areas are the major source
regions of glaciers.

7.  A lot of material is eroded and transported by glaciers.
 The erosional work is carried out through.
* Abrasion(friction)
* Plucking (breaking or digging out of rocks.
. obstructing the passage of the Glaciers.)

9. Types of Glaciers.

10. Classification of Glaciers
H.W. Ahlmann.
has provided two types of
glaciers classification
1) Morphological
classification
2) Thermal classification

11. Morphological classification
 Generally glaciers originate in areas above the snow line (the lowest limit of
the perpetual snows.
 a) Continental glaciers or ice –sheet covering large areas


15. • Ice caps
are
smaller
than
continenta
l glaciers

16. c) Highland glaciers.
Highland glaciers found
in the high portions of the
mountains

17. Cirque glaciers
occupying
valley heads or
rock basins on
mountain slope
at high altitude

18. Valley glaciers or Alpine glaciers

19. The valley glaciers, also known as Alpine
glaciers, are found in higher regions of the
Himalayas in our country and all such high
mountain ranges of the world.
The largest of Indian glaciers occur in the
Karakoram range, viz. Siachen (72 km),

22. Transection glaciers
Transection glaciers covering a whole valley
system

25. Thermal classification
Temperate Glaciers
Cold Glaciers

26. Temperate Glaciers
 These glaciers are characterised by presence of melt
water.
 The melt water at the bed helps the ice slide over the
wet rock floor
 Thus the rate of movement of these glaciers is
generally more than that of the other glaciers.

27. Cold Glaciers
 Glaciers that are below the freezing point throughout the
year.
 Two sub-types
 1). High polar type. 2). Sub polar type
 High polar type the temperature is below the freezing
point throughout the year.
 There is no melting on the surface even in summer

28.  Sub –Polar type
 The material consists of crystalline down to a depth
of 10 to 20 metrs.
 In summer the surface may melt and the water may
be present
 The ice at the bottom in both sub types is frozen

29. Erosional landforms

30. U – Shaped valley
 The glacier being solid, it cannot adopt the shape of the valley
through which it flows. Hence the sides of the glacial valley are
steep and it is almost as wide at the base as at the top.
 Such valley is called a U – shaped valley.
 This type of valley is a result of the plucking and abrasion, both
going together.

31.  Its sides as well as the bottom
are smoother than the v-
shaped valley of river.
 glacial mass is heavy and
slow moving, erosional
activity is uniform –
horizontally as well as
vertically.
 A steep sided and flat
bottomed valley results,

34. Hanging valleys
A valley carved out by a small
tributary glacier that joins with a
valley carved out by a much
larger glacier.
The tributary valleys joining a
major glacial valley. Such valleys
of the tributary glaciers are called
hanging valleys.
Hanging valley

35.  The erosional capacity of a glacier is
propotional to the mass of ice involved
in the movement.
 As a result major glacier deepen their
valleys at a faster rate than the smaller
tributaries that join the major glacial
valley
 Forming waterfall

37. Cirque
 A Cirque is a semi –circular steep sided depression
Formed through glacial erosion
 A cirque is formed at the head of a valley glacier where
some snow accumulates and is compacted to form a
cirque glacier.
 Ice moving down a steep slope causes headward
erosion and the steep hill slope is cut in a concave form
which is shaped like a deep seated armchair.
 It has steep sided slope on three sides, an open end
on one side and a flat bottom.

40.  They are also known as
 Corries in Scotland
 Cwm in wales
 Kar in Austria
 Nisch in sweden
 The term cirque is of French origin

41. Tarn lake or Cirque lake
 When the ice melts,
the cirque may
develop into a tarn
lake.
 Lakes are generally
found in the bottoms
of the cirques.

43. Aretes
 When cirques are formed on two
sides of a mountain range the
mountain divide becomes
narrow due to cutting backwards
by the glaciers on the opposite
sides.
 Such steep sharp edged ridges
are called aretes (French), grat
(German)
 Steep-sided, sharp-tipped

48. Horn
 A Horn results when glaciers erode three or more
aretes, usually forming a sharp edged peak..
 Horns are the unreduced portions of the mountain
ridge.
 They appear like a pyramidal peaks with steep side
slope.
 They are the characteristic of the high glaciated
regions.
 Topography of such regions is called Serrated
topography

51. Crag and tail
 A crag is a rocky hill or mountain, generally isolated from other high
ground.
 Crags are formed when a glacier or ice sheet passes over an area that
contains a particularly resistant rock formation (often a granite, volcanic
structure).
 The force of the glacier erodes the surrounding softer material
 The crag is steep slope where the limited erosion of the harder rock has caused
the steep slope
 The land behind the crag is protected and forms a long, gently sloping
ridge called the tail.

53. Roches Moutonnees or Sheep rock
 roche moutonnée (or sheep rock) is a rock
formation created by the passing of a glacier.
 roche moutonnée are formed when a glacier
moves over an dome shaped area.
 The slope along which it climbs is abraded
smoothly.
 As the glacier descends the slope of the dome
on the opposite side
 The rocks are plucked to form a rough and
steeper slope.

56. Fjord
 Some of the glaciers reach oceans and seas before they melt
 It happens often in the high latitude regions where the snow line reaches the
sea level
 Some cases it joins the sea directly and it erodes the coastal part of the sea.
 Thus the erosion in the coastal area continues below the sea level.
 This produce submerged valleys with very steep sides due to sea level rise
 Steep-sided narrow entrance-
 These submeged U shape valley are called fiords

58. Depositional Landforms

59. Glaciers hardly create any
depositional features before they
melt
Most of the deposition by glaciers
therefore occures in the zone of
melting.

60. Moraines
 The loads carried by glaciers are called moraines.
 Moraine is material transported by a glacier and then
deposited.
 General term applied to rock fragments, gravel, sand,
etc. carried by a glacier.
 Moraines are classified into various categories on the
basis of the part of the body of the glacier carrying the

61. Lateral Moraine

Lateral moraine forms along the
edges of the glacier.
 It is then carried along the sides
of the glacier.
 When the ice melts it forms a
ridge of material along the
valley side.

64. Medial Moraine
The rock debris being
transported in the
central or the middle
part of the body of the
glacier forms the medial
moraine.

67. Ground Moraine
Material is
transported by
the glaciers
along the bottom
of the their
valleys.

69. Terminal Morine
 The glaciers
push of a lot
of rock
debris in
front of
ground
moraine

72. Recessional Moraine

Recessional
moraines form at
the end of the
glacier so they are
found across the
valley, not along it.

74. Till plains
 Till is a mixture of sand,
silt,clay with some
amount of pebbles and
large boulders.
 A till plain is an
extensive flat plain
of glacial till

76. Drumlin
 Smooth, streamlined, oval,or elongated
mounds or small rounded hills found in the
till plains are called drumlins.
 As the glacier starts melting, large
quantities of gravel material are deposited
in the shape of inverted boats.
 The slope of this type of deposits is steep
towards the snout (front portion )of the
glacier and gentle in the down stream
direction

77. They are elongated
features that can
reach a kilometer or
more in length, 500m
or so in width and
over 50m in height.

80. Fluvio – Glacial Deposits
 The drumlins and the morains are almost completely glacial
deposits in the sense that in their formation there is no role of
melt water streams.
 The lower portion of the glacier starts melting due to frictional
high temperature in the bottom and the water thus released
flows under the ice in the form of a stream flowing through a
tunnel.
 This water issuing from the tunnel below the glacier creates
certain topographical features..
 These features are called fluvio-glacial features.

81. Eskers
 Eskers are longitudinal deposits formed in the tunnel
under the glacier.
 Eskers are produced as a result of running water
in, on or under the glacier.
 They are linear mounds of sand and gravel that
commonly snake their way across the landscape.
 They are like longitudinal ridges of the deposited
materials having 60 to 90 metres hight
 Winding ridge of un-assorted depositions of rock,
gravel, clay etc.
 The width of eskers is not uniform

84. Kames
 Broken ridges or un-assorted
depositions looking like hump in a till
plain.
 Kames are small dune –like
formations that comprise smaller
sized deposits near the snout of the
glacier.
 They are found surrounded by
terminal moraines
 They are rounded in shape

87. Outwash Plains
 When the glacier melts, the melt
water accumulate near the
terminal moraine .
 It flows in the form of a river
transporting a lot of material
deposited as terminal moraines.
 The water in this area spreads
out over a broad area.
 These deposit is known as
outwash plain

91. Kettle Holes
 Formed when the deposited
material in a Outwash plain gets
depressed locally and forms a
basin.
 Kettles are depressions in the
outwash plains.
 Kettles are formed due to melting
of large blocks of ice

94. SELMANUL FARIS P