physical weathering gtag ppt gtu

1. Physical Geology
Geological Work of wind
The Movement of atmosphere in a direction parallel to the
earth surface, is wind
Vertical movements are termed as air currents

2. Physical Geology
Geological Work of wind
The Entire geological work performed by wind can be studied
1) Erosion
2) Transportation
3) Deposition

3. Physical Geology
Wind
The Entire geological work performed by wind can be studied
1) Erosion
2) Transportation
3) Deposition

4. Physical Geology
Wind Erosion
Wind performs work of erosion in three ways:
1) Deflation
2) Abrasion
3) Attrition

5. Physical Geology
Wind Erosion
1) Deflation
Wind doesn’t have much erosive power over rocks or over
ground cover with vegetation but moving with sufficient
velocity over dry and loose sand removes sand and dust by
strong wind is called deflation.

6. Physical Geology
Wind Erosion
1) Deflation – Blowout
Some Desert Deflation removes
sand from a particular location that
create a big depression are called
blowout

7. Physical Geology
Wind Erosion
2) Deflation – Oasis
Much deeper extensive
depression where water
table is intersected and
gets partially filled with
water is called oasis.

8. Physical Geology
Wind Erosion
3) Deflation – Hammada
Bare rock surface in a
desert from over which
thin cover of sand has
been blown away by
strong winds.

9. Physical Geology
Wind Erosion
2) Abrasion
Wind become a powerful agent for rubbing rock surface when
naturally loaded with sand and dust particles. Erosion
involving rubbing and grinding of rock surface by wind with
help of its load while passing over rock is termed as abrasion.

10. Physical Geology
Wind Erosion
1) Abrasion – Pedestal Rock
Pedestal rock are the undercut
vertical columns of rocks which
have wider tops and narrow
bases.
Also Called Mushroom Rock.

11. Physical Geology
Wind Erosion
2) Abrasion – Yardangs
Low lying, elongated ridges,
forming overhangs above local
depressions.

12. Physical Geology
Wind Erosion
3) Attrition
Sand particles lifted by wind from different places are carried
away to considerable distances, during journey particles move
in zig-zag fashion, colliding with one other again and again.
This phenomena termed as attrition.
Depends on 3 factors Nature of region, Velocity of wind and
Duration of Erosion.

13. Physical Geology
Wind Transportation
Wind performs work of Transportation in two ways:
1) Suspension
2) Saltation

14. Physical Geology
Wind Transportation
1) Suspension
The light density clay
particles may be lifted by
the wind from ground and
move along with winds is
called suspension.

15. Physical Geology
Wind Transportation
2) Saltation
The heavier and coarse sediments
are lifted up with high velocity and
short distance above ground up to
2 m. They picked up and drop again
during the transportation process
of bouncing and jumping is called
saltation.

16. Physical Geology
Wind Deposition
When velocity of a fast blowing sediment checked by some
obstruction like hills, mountains, change in climate or
presence of water bodies etc. the sediments get dropped and
deposited, forming what are known as Aeolian deposited.
Two types of Aeolian deposits are
1) Sand Dunes
2) Loess

17. Physical Geology
Wind Deposition
1) Sand Dunes
Wind generally deposits sand in a
mounds. This mounds are called
sand dunes.

18. Physical Geology
Wind Deposition
2) Loess
Loess are blanket deposits of silt &
clay formed by suspended loads of
winds.
Loess composed by minerals
including quartz, feldspar, calcite.

20. Physical Geology
Geological Work of River
Geological work of river can be subdivided into 3 stages
1) River Erosion
2) River Transportation
3) River Deposition

21. Physical Geology
River Erosion
Streams and rivers are the most powerful agents of erosion.
The Rivers carries out erosion work in five different ways
1. Hydraulic Action
2. Cavitation
3. Abrasion
4. Attrition
5. Corrosion

22. Physical Geology
River Erosion
I. Hydraulic Action
Mechanical Loosening &
Removal of materials from the
rocks due to pressure exerted by
running water.

23. Physical Geology
River Erosion
I. Hydraulic Action
 is more effective if
•Rocks already weathered
•They are porous
•They have easily soluble
material
•Crack or weak planes are
available

24. Physical Geology
River Erosion
II. Cavitation
If stream velocity exceeds 12m/sec, the water pressure is
equal to vapour pressure, hence spontaneous change from
liquid to vapour state and back to liquid state at that point will
result in sucking out of the material at that point which creates
holes in rock mass. This phenomenon is called cavitation.

25. Physical Geology
River Erosion
III. Abrasion
Physical break down of soil masses which exposed along the
sides and bottom of the river which are transported by the
river.

26. Physical Geology
River Erosion
III. Abrasion
This process mainly influenced by
•Nature of Sediments
•Velocity of River
•Presence of Joints in Rocks

27. Physical Geology
River Erosion
IV. Attrition
•During transportation, heavier and larger materials move
slowly, while light material moves fast. This movements result
in collision, repetitively outcomes attrition.
•When attrition takes place angular edges formed into spherical
stones.

28. Physical Geology
River Erosion
V. Corrosion
Slow but steady chemical action of he stream water on the
rocks is expressed by the term corrosion.

29. Physical Geology
River Erosion
River Meandering
When a stream flows along a curved, zigzag path acquiring a
loop shaped course, is said to meander.
This development of zigzag type of channel for itself is called
river meandering.

30. Physical Geology
River Meandering

31. Physical Geology
River Meandering

32. Physical Geology
River Meandering

33. Physical Geology
River Meandering

34. Physical Geology
River Meandering

35. Physical Geology
River Meandering

36. Physical Geology
River Meandering

37. Physical Geology
River Meandering

38. Physical Geology
River Meandering

39. Physical Geology
River Meandering

40. Physical Geology
River Meandering
Oxbow Lake
•During meandering process river beds increasing progressively
and neck becomes narrow and narrow. Finally a stage comes
where river cuts through neck and start flowing straight leaving
behind roundabout course.
•Such left old meanders filled with water are known as Oxbow
Lakes.

41. Physical Geology
River Meandering
Oxbow Lake

43. Physical Geology
River Transportation
River carries soil and rock materials, which it continued
erosion from itself as well as material disintegrated from side
slope by weathering process or rain wash etc. The river also
contribute a lot of sediment material to it.
The Sediment material flowing in a river is called load.

44. Physical Geology
River Transportation
Load may be considered in three parts.
1) Dissolved Load
2) Suspended Load
3) Bed Load

45. Physical Geology
River Transportation
1) Dissolved Load
This includes particles of material soluble in water, which river
gain due to solvent action on the rocks of the channel.
Rivers from land part carry calcium carbonate, sodium chloride
and other soluble salts from limestone, gypsum, rock salt etc.

46. Physical Geology
River Transportation
2) Suspended Load
The Suspended material consist of finer materials like fine
sand, silt clay etc. which kept in suspension by the turbulence
of water and therefore carried over long distance.

47. Physical Geology
River Transportation
3) Bed Load
The river load contains heavier particles of sand, gravels,
pebbles and cobbles which are moved along with bed of river is
called bed load.

48. Physical Geology
River Deposition
The entire sediment load of river will normally transport
unless there is a change in other factors responsible for
transport. As there is a decrease in load carrying capacity of a
stream dropped down, a dropped down load is called river
deposition.
Deposits laid down by running water are called fluvial
deposits.

49. Physical Geology
River Deposition
Delta
•When a river enters a body of standing
water like lake or sea, its flow velocity
considerably reduced, which results in
sediment material deposition near
shore line . Which forms plan to a
Greek latter delta.

51. Physical Geology
Geological Work of Glaciers
A Glacier is a thick mass of ice which moves over ground
under influence of gravity.
It originates on the land from the compaction and
crystallization of snow.

52. Physical Geology
Geological Work of Glaciers
Three Kinds of Glaciers
1) Valley Glaciers
2) Piedmont Glaciers
3) Ice Sheets

53. Physical Geology
Geological Work of
Glaciers
1) Valley Glaciers
•Glaciers Originates near crest
of high mountain and move
along like valley just like
rivers, are called glaciers.

54. Physical Geology
Geological Work of
Glaciers
2) Piedmont Glaciers
•@ end of hilly region, no. of
valley glaciers unite to form a
thick sheet of ice. Such
compound glaciers called
piedmont glaciers.

55. Physical Geology
Geological Work of Glaciers
3) Ice Sheets
•Also known as continental glaciers
because of extensive cover & mass.
•They are so thick that surface
features of ground buried under
them.

56. Physical Geology
Geological Work of Glaciers
Glacial Erosion
•Erosion by glaciers is caused in 3 ways
1) By Plucking
2) By Abrasion
3) By Frost Wedging

57. Physical Geology
Geological Work of Glaciers
Glacial Erosion
1) By Plucking
•Process of loosening a rock mass and
then pulling out blocks after loosened
bed rock.

58. Physical Geology
Geological Work of Glaciers
Glacial Erosion
2) By Abrasion
•Rubbing, Scratching and polishing
action of glaciers on the rock surface
along or over which ice mass happen to
move.

59. Physical Geology
Geological Work of Glaciers
Glacial Erosion
3) By Wedging action of ice
•Hawing and freezing of water in cracks
and joint of rocks, break them by
wedging action.