Weathering is the process that breaks down rocks, soils, and minerals through interactions with the atmosphere, biota, and water. It includes mechanical, chemical, and biological types, influenced by factors like climate, rock type, and topography, and plays a key role in erosion, soil formation, and the rock cycle. Understanding weathering is essential for grasping how landscapes are formed and affected by natural and human activities.

1. Weathering: The
Shaping Force of
Earth
Weathering is the process that breaks down rocks, soils, and minerals
through direct contact with the Earth's atmosphere, biota, and waters.
by MICHAEL DENIEGA

2. Mechanical Weathering
1 Frost Wedging
Water freezes in cracks,
expands, and widens the
fissures, gradually breaking
down rocks.
2 Thermal Stress
Rapid temperature changes
cause rocks to expand and
contract, leading to
fracturing and eventual
disintegration.
3 Salt Wedging
Salt crystals grow in rock
pores, exerting pressure
that causes the rock to
break apart.
4 Abrasion
Rocks are ground down by
the friction of moving
particles like windblown
sand or waterborne
sediment.

3. Chemical Weathering
Dissolution
Rocks are dissolved by acidic water, such as rainwater that has
absorbed carbon dioxide from the atmosphere.
Oxidation
Iron in rocks reacts with oxygen, forming iron oxide (rust) and
weakening the rock structure.
Hydrolysis
Water reacts with minerals in rocks, breaking them down into
new compounds, such as clay.
Carbonation
Carbon dioxide dissolves in water to form carbonic acid, which
reacts with calcium carbonate in rocks, leading to dissolution.

4. Biological Weathering
1
Plants
Plant roots grow into cracks, expanding and breaking rocks apart.
2 Animals
Burrowing animals like earthworms and moles create tunnels that
expose rocks to weathering.
3
Lichens
Lichens produce acids that chemically weather rocks, creating a
substrate for their growth.
4 Bacteria
Bacteria break down organic matter and release acids that can
contribute to chemical weathering.
orientation=vertical twosided=false

5. Factors Affecting Weathering
Climate
Temperature, rainfall, and freeze-
thaw cycles influence weathering
rates.
Rock Type
Different rocks have varying
resistance to weathering based on
their mineral composition and
structure.
Topography
Slope, elevation, and exposure to
sunlight affect weathering rates.

6. Weathering and Erosion
Weathering
Breaks down rocks into smaller
fragments.
Erosion
Transports weathered material by wind,
water, or ice.
Deposition
Weathered material is deposited in new
locations, shaping landscapes.
orientation=horizontal

7. Weathering Processes in Different Climates
Climate Dominant Weathering Processes
Arid Physical weathering, such as abrasion by wind and salt wedging.
Tropical Chemical weathering, due to high temperatures and humidity.
Glacial Physical weathering, caused by the grinding action of ice.
Coastal Physical weathering, from wave action and salt spray.

8. Weathering and Soil
Formation
Parent Material
Weathered rock fragments
provide the foundation for soil.
Organic Matter
Decomposed plant and animal
remains enrich the soil.
Water
Rainfall and groundwater
influence soil development and
nutrient transport.
Climate
Temperature, rainfall, and other
climatic factors shape soil
properties.

9. Weathering and Rock Cycle
1
Weathering
Breaks down rocks into smaller fragments.
2 Erosion and Transportation
Weathered material is moved by wind, water, or ice.
3
Deposition
Weathered material is deposited in new locations.
4 Lithification
Sediments are compacted and cemented to form sedimentary
rocks.
5
Metamorphism
Heat and pressure transform sedimentary rocks into
metamorphic rocks.
6 Melting and Cooling
Metamorphic rocks melt and cool to form igneous rocks.
orientation=vertical twosided=false

10. Importance of Understanding Weathering
Weathering plays a critical role in shaping the Earth's surface, influencing soil formation, geological processes, and human
activities.