glacial environment , formation ,types ,movment , erosion ,deposition

1. Glacial Environment

2. Every thing starting as a
Snow Flake and snow
flake is a beautiful
hexagonal crystal of ice

3. Formation of snowflakes

4. Formation of snowflakes

6. As the snow accumulates, it
is gradually transformed
into ice. The weight of
overlying snow packs it
down, drives out much of
the air, and causes it to
recrystallize into a coarser,
denser form (Firn) an
intermediate texture
between snow and ice, and
finally to a compact solid
mass of interlocking ice
crystals

7. This process may take a few seasons or several
thousand years, depending on such factors as
climate and the rate of snow accumulation at the
top of the pile

8. Glaciers
A large mass of moving
ice Capable of eroding,
moving, and depositing
large amounts of
material.

9. Types
Mountain or Alpine glaciers :
Forms over the mountains and the ice start flowing
down to form valleys

10. Once formed, the weight of snow accumulating in
the upper part of the glacier causes it to move
downslope, where it reaches lower altitudes and
higher temperatures. The lower part of the glacier
is the ablation zone where the glacier melts during
the summer.

11. Under stable climatic conditions equilibrium develops
between accumulation at the head and melting at the
front, with the glacier moving downslope all the time, but
the positions of the head and snout remain fixed

12. Zone of accumulation (input)
Zone of ablation (ablation
exceeds accumulation)

13. Continental glaciers
Much larger and
thicker
forming massive
sheets of ice
2 polar ice sheets
Greenland
Antarctica

14. Ice sheet
Extends over 50,000 km2
Antarctic and Greenland

15. Ice cap
Similar to an ice sheet though smaller
Forming roughly circular, dome-like structure

16. Continental glaciers

17. Glaciers do not behave as rigid, Their flow is
plastic
High pressure and some times geothermal heat
causing in melting of the layer at the base so
ice start sliding
Move by two basic processes:
Basal Slip – the process causing the ice at
the base of a glacier to melt and the glacier
to slide.
Internal Plastic Flow(internal deformation) –
the process by which glaciers flow slowly as
grains of ice deform under pressure and
slide over each other.
Movement

18. Internal deformation

19. Glacial advancing
When
accumulation
rate exceeds
ablation
rate so we
have glacial
advancing

20. Glacial Retreating
When accumulation rate less than
ablation rate we have glacial
retreating

21. GLACIAL EROSION
Mechanism involved…
Plucking
Glacier flows over a
fractured bedrock surface
it loosens and lift blocks of
rocks and incorporate
them into ice
Notice that this process
seasonable and image just
for clarifying

22. Abrasion
Happens when ice and its load of rock
fragment slides over bedrock

23. Plucking and abrasion

24. Freeze Thaw

25. The glacial processes that change the shape of
mountains begin in the upper end of the valley where
an alpine glacier forms.

26. How selected features of continental glaciation, including kames, originated.
During Glacial
Cirque and Arêtes form and glacial creates
a U shaped valley

27. Postglacial

28. Features of alpine Glaciation
Erosional features
Cirques
Arêtes
Horns
Truncated spurs
U-shaped valleys
Hanging valleys
Tarns and paternoster lakes
Depositional Features
Moraines

29. Cirque formation

30. An arête is a sharp ridge
formed when two cirques cut
back
Arête

31. Features of alpine Glaciation
a)Horn( b)Cirque (c)Arete

32. a)Horn (b)cirque (c) U shape valley
a
b
c

33. a)Horn (b)cirque(c)arete (d)truncated spurs
a
a
a
b bb
c
c
d
b

34. U shape valley after glaciation

35. Hanging
valley

36. Tarn

37. Paternoster lakes

38. Glacial Deposition
Landforms resulting from a glacier depositing
till are called moraines.
Lateral moraine: deposited along the
sides of an alpine glacier, usually as a
long ridge.
Medial moraine: form when the
lateral moraines of alpine glaciers
meet.
Ground moraine: unsorted materials
left beneath the glacier when the ice
melts.
Terminal moraine: small ridges of till
deposited at the leading edge of a
melting glacier.

45. Ground Morains

46. Erosional features
roche moutonnée
Depositional features
Terminal moraines
Till plain, outwash plain
Eskers
Kettles
Kames
Erratics
Drumlins
Features of Continental Glaciation

47. Roche moutonnée

50. Roche moutonnée (sheepbacks)
Ice flow
Stoss side
Lee side

51. How selected features of continental glaciation, including kames, originated.

54. Eskers
Melt water forms a
tunnel under a glacial
ice sheet
Tunnel fills with rocks,
sand and gravel
After retreat of the
ice, material
collected in the
tunnel is left to
form a ridge

55. Kettle lake
A big chunk of ice trapped then melted to form
kettle lake and sediments deposited around it

56. Erratics
Large rocks transported
from a distant source by
a glacier

57. Erratics

58. Erratics

59. Deposition: drumlins
Oval shaped hills
Formed of till left by glaciation
Blunt end facing opposite ice flow
Often found in “shoals”

60. Drumlins
Ice flow

61. Eskers – economic benefits
Mined for materials – sand,
gravel and stones for
construction
Used for natural water
filtration

62. Glaciers are not only large masses of ice; they
can also be viewed as an important freshwater
reserve. Approximately 75% of the fresh
water on earth is stored as ice in glaciers
Important source for deposits
Climate and environment indicator
General Benefits

63. Glacial Geology, Ice Sheets and Landforms [Matthew M.
Bennett, Neil F. Glasser]
Sedimentologyandstratigraphy 2nd edition by Gary
Nichols
Environmental geology , carla c montgomry
Further reading

64. Regards,
AmrElgabry