The document discusses exogenic processes that shape the Earth's surface. It describes weathering as the breakdown of rocks into smaller pieces through mechanical or chemical means. The main types of weathering are physical, chemical, and biological. Physical weathering breaks rocks through stresses like frost cracking or heat expansion. Chemical weathering alters rocks through reactions with acids, oxygen, or water. Biological weathering occurs when organisms like lichen or plant roots interact with rocks. Erosion is then able to transport weathered rock and sediment particles via agents like wind, water, glaciers or gravity. These erosional processes ultimately lead to deposition of sediments in new locations.

1. EARTH AND LIFE SCIENCE
Exogenic
Processes
https://www.youtube.com/watch?v=ysgZogSBMio

2. QUESTION:
What are the processes that
helped shape the Earth’s
surface?

3. OBJECTIVE:
After going through this module, you
are expected to:
1. describe how rocks undergo
weathering;
2. identify the agents of erosion; and
3. explain how the products of
weathering

4. WHAT IS EXOGENIC PROCESSES?
• Are processes that take place at or
near the earth’s surface that makes
the surface wear away.
• Are very destructive, they are
responsible for degradation and
sculpting the Earth’s surface.

5. HUGE SOIL EROSION WAS SEEN IN SAN ROQUE, MALILIPOT, ALBAY

6. TYPES OF EXOGENIC PROCESSES
1. Weathering
2. Erosion
3. Mass Wasting
4. Sedimentation

7. WEATHERING
The process that breaks down
rocks into smaller pieces

8. KINDS OF WEATHERING
1. Mechanical/Physical
Weathering –
the mechanical/physical
breakdown of rock into smaller
pieces (sediments), without a
change in the mineral’s chemical

9. KINDS OF WEATHERING
1. Mechanical/Physical
Weathering
• Exfoliation
• Frost Wedging
• Salt Wedging
• Temperature Changes
• Abrasion

10. KINDS OF PHYSICAL WEATHERING
• Exfoliation is a mechanical
weathering process in which
pressure in a rock is released
(unloading) along parallel
alignments (sheet joints) near the
surface of the bedrock and layers or
slabs of the rock along these
alignments break off from the

11. KINDS OF PHYSICAL WEATHERING
• Exfoliation primarily occurs on
intrusive igneous or
metamorphosed rocks that are
exposed at the Earth’s surface.

12. KINDS OF PHYSICAL WEATHERING
• Frost wedging is a
mechanical
weathering process
caused by the
freeze-thaw action
of water that is
trapped between
cracks in the rock.

13. KINDS OF PHYSICAL WEATHERING
• When water
freezes, it expands
and applies
pressure to the
surrounding rock
forcing the rock to
accommodate the
expansion of the
ice.

14. KINDS OF PHYSICAL WEATHERING
• Frost wedging
generally produces
angular blocks and
talus material. Talus
is a term used to
describe weathered
rock fragments
deposited at the
base of a hill slope

15. KINDS OF PHYSICAL WEATHERING
d. Temperature Changes -alternating hot and
cold temperatures weaken the rock as it
expands and contracts.
This gradual
expansion and
contraction of mineral
grains weakens
the rock causing it to
break apart into
smaller fragments or
to fracture

16. KINDS OF PHYSICAL WEATHERING
d. Salt wedging - occurs when salts crystallize
out of solution as water evaporates. As the salt
crystals grow, they apply pressure to the
surrounding rock weakening it, until it
eventually
cracks and breaks down, enabling the salt
crystal to continue growing.

17. KINDS OF PHYSICAL WEATHERING
e. Abrasion occurs when rocks
collide against each other while
they are transported by water,
glacial ice, wind, or gravitational
force.

18. KINDS OF PHYSICAL WEATHERING
e. Abrasion The constant collision
or gravitational falling of the rocks
causes them to slowly break apart
into progressively smaller particles

19. KINDS OF WEATHERING
1. Chemical Weathering –
decomposes, dissolves, alters, or
weakens the rock through
chemical processes to form
residual materials.

20. KINDS OF WEATHERING
1. Chemical Weathering –
• Carbonation
• Hydrolysis
• Hydration
• Oxidation
• Solution

21. KINDS OF CHEMICAL WEATHERING
a. Carbonation - is a process by
which carbon dioxide and water
chemically react to produce carbonic
acid, a weak acid, that reacts with
carbonate minerals in the rock.
• This process simultaneously
weakens the rock and removes the
chemically weathered materials.

22. KINDS OF CHEMICAL WEATHERING
a. Carbonation primarily occurs in
wet, moist climates and effects
rocks both on and beneath the
surface.
- Carbonation occurs with limestone
or dolomite rocks and usually
produces very fine, clayey particles.

23. KINDS OF CHEMICAL WEATHERING
b. Hydrolysis is a chemical reaction
between H+ and OH- ions in water and
the minerals in the rock. The H+ ions
in the water react with the minerals to
produce weak acids.

24. KINDS OF CHEMICAL WEATHERING
b. Hydrolysis
• The reaction creates new
compounds which tend to be softer
and weaker than the original parent
rock material.
• Hydrolysis can also cause certain
minerals to expand, which also
facilitates mechanical weathering
processes.

25. KINDS OF CHEMICAL WEATHERING
b. Hydrolysis
• when water reacts with a mineral to form
a new mineral with H20 as part of its
crystal structure

26. KINDS OF CHEMICAL WEATHERING
c. Hydration - is a process where
mineral structure in the rock forms a
weak bond with H20.
• Mineral grains expand, increased
stress promotes the of the rock.
disintegration
• Often color changes in the
weathered rock surface.

27. KINDS OF CHEMICAL WEATHERING
c. Hydration - An example:
• Anhydrite (CaSO4) can absorb two
water molecules to become gypsum
(CaSO4 ·2H2O).

28. KINDS OF CHEMICAL WEATHERING
d. Oxidation occurs when an ion in a
mineral structure loses an electron to
an oxygen ion.
• Occurs when a mineral reacts with
O2.
• Example: Iron (Fe) + Oxygen gas
(O2) = FeO2 (rust)

29. KINDS OF CHEMICAL WEATHERING
e. Dissolution occurs when minerals in
rock dissolve directly into water.
• dissolution most commonly occurs on
rocks containing carbonates , also
affects rocks with large amount of halite,
or rock salt.
• Solution of large areas of bedrock may
cause sinkholes to form, where large
areas of the ground subside or collapse
forming a depression.

30. KINDS OF WEATHERING
3. Biological weathering is the
disintegration or decay of rocks
and minerals caused by chemical
or physical agents of organisms.

31. KINDS OF WEATHERING
3. Biological weathering
• Organic activity from lichen and
algae
• Rock disintegration by plant
growth

32. KINDS OF WEATHERING
3. Biological weathering
• Organic activity from lichen and
algae
• Rock disintegration by plant
growth

33. KINDS OFBIOLOGICAL WEATHERING
a. Lichen, Algae, and Decaying Plants
• Organisms such as lichen and algae
often live on bare rock and extract
minerals from the rock by ion-
exchange mechanisms.
• This bio-chemical weathering
process leaches minerals from the
• rock causing it to weaken and

34. KINDS OFBIOLOGICAL WEATHERING
a. Lichen, Algae, and Decaying Plants
• Organisms such as lichen and algae
often live on bare rock and extract
minerals from the rock by ion-
exchange mechanisms.
• This bio-chemical weathering
process leaches minerals from the
• rock causing it to weaken and

35. KINDS OFBIOLOGICAL WEATHERING
b. Plant Roots
• Plant roots penetrate into cracks and
crevices of rocks and cause the rock
to split or break into smaller
particles through mechanical
weathering.
• Process enhanced in rocks that may
already have a pre-existing
weaknesses such as fractures, faults,

36. KINDS OFBIOLOGICAL WEATHERING
c. Organism Activity
• Burrowing, tunneling, and acid-secreting
organisms chemically or mechanically
weather rocks.
• Burrowing organisms disintegrate rock.
Small animals, worms, termites, and other
insects.
• Snails, barnacles, or limpets, attach
themselves to rocks and secrete acid acids
that chemically dissolve the rock surface.

37. KINDS OF WEATHERING
4. Differential Weathering
• Rates are controlled by the type of
weathering processes and rock material.
• Harder rocks typically weather slower
than softer rocks in the same env.
• The differences in rates of weathering
due to types of rocks, textures, or other
characteristics is referred to as
differential weathering.

39. EROSION
• Erosion is defined as removal of
rocks and soil by wind, water, ice
and gravity.
• Wind, water, ice and gravity are
also known as the agents of
erosion.

40. EROSION
• Weathering has to happen
before erosion. The rocks have to
be broken into smaller sediments
before they can be eroded away.

41. AGENTS OF EROSION
• WIND
• FLOWING WATER
• WAVES
• GRAVITY
• MOVING ICE

42. WHAT IS WIND EROSION?
Wind Erosion – sediments that have
been transported by wind appear pitted
(holes) and frosted (glazed)
• – Effective in moving small, loose
material
• – Occurs in areas where there is
not enough rainfall to support
vegetation

43. WHAT IS WIND EROSION?
Main effects:
1. Wind causes small particles to be
lifted and moved away.
2. 2. Suspended particles may
impact on solid objects causing
erosion by abrasion (rubbing).

44. WHAT IS WATER EROSION?
Flowing Water – sediments
transported by water appear
rounded and smooth
– Most influential force in erosion
– Transports large objects with fast
moving streams
– Helps create landforms:
• rivers • lakes • oceans

45. WHAT IS WAVE EROSION?
Wave erosion – relentless pounding can
throw broken rocks against the shore and
wash away fine grains
• Erodes (transports):
1. softer/weaker rock first
2. harder/more resistant left behind
Can create landforms based on where waves
hit land and which rocks they transport

46. WHAT IS WAVE EROSION?
Wave erosion – relentless pounding can
throw broken rocks against the shore and
wash away fine grains
• Erodes (transports):
1. softer/weaker rock first
2. harder/more resistant left behind
Can create landforms based on where waves
hit land and which rocks they transport

47. WHAT IS WAVE EROSION?
Wave erosion – relentless pounding can
throw broken rocks against the shore and
wash away fine grains
• Erodes (transports):
1. softer/weaker rock first
2. harder/more resistant left behind
Can create landforms based on where waves
hit land and which rocks they transport

48. WHAT IS GRAVITATIONAL EROSION?
Gravitational Erosion – downward
movement of rock and sediments, mainly
due to the force of gravity
– Streams and glaciers
• move material from higher to lower
elevation
– Occurs continuously on all slopes

49. WHAT IS GLACIAL EROSION?
Glacial erosion – moving
ice that carries rocks;
appear scratched and
grooved

50. WHAT IS GLACIAL EROSION?
Glacial erosion – moving
ice that carries rocks;
appear scratched and
grooved

51. WHAT IS DEPOSITION?
Deposition– the process
where sediments are
released/dropped by their
agent of erosion

52. ASSIGNMENT:
Bring the following:
1. Short bond paper
2. Pencil
3. Coloring materials

53. ACTIVITY 1
Include the
following details:
a. Weathering
b. Type of
weathering
c. 2 sentences
that
explains
your
drawing