Weathering & Mass Wasting or Mass Movement of Earth

1. Weathering & its types
2. Mass Wasting & its types

2. Weathering: all the processes that physically
disrupt or chemically decompose a rock
at or near the Earth’s surface
Two types of weathering:
1.Physical or Mechanical weathering
2. Chemical weathering
Weathering produces regolith

3. Mechanical weathering breaks rocks into
smaller pieces
◦Frost action
◦Salt crystals
◦Roots
◦Exfoliation
Rock chemistry does not change
Regolith:
layer of mineral particles that lies above bedrock

4. •Frost Action: water
expands when
•it freezes, and fractures
rock
Joints: fractures in
bedrock
Granular disintegration:
rocks break up grain by
grain

5. Salt-crystal growth: Water
evaporates from sandstone
pores, leaving salt crystals
behind. Crystals grow and
disintegrate rock.
Occurs in arid and semiarid
regions

6. Unloading: rock is exposed
at the surface, releasing
pressure, so rock expands
slightly
Sheeting structure: rock
joints in layers parallel to
surface, forming exfoliation
domes
Other possible processes of
physical weathering:
Temperature change
Plant roots

12. The process that breaks down rock through
chemical changes.
Chemical weathering changes the chemistry
of rocks
◦Oxidation (exposure to oxygen)
◦Hydrolysis (exposure to water)
◦Carbonation (exposure to carbon dioxide)
◦Living organisms
◦Acid rain
Warmth and water encourage chemical reactions
Weathering loosens rock particles, creates soil

14. Water weathers rock by dissolving it

16. Iron combines with oxygen in the presence of
water in a processes called oxidation
The product of oxidation is rust

17. CO
2dissolves in rain water and creates
carbonic acid
Carbonic acid easily weathers limestone and
marble

18. Lichens that grow on rocks produce weak
acids that chemically weather rock

19. Compounds from burning coal, oil and gas
react chemically with water forming acids.
Acid rain causes very rapid chemical
weathering

20. A type of landscape in rainy regions where
there is limestone near the surface,
characterized by caves, sinkholes, and
disappearing streams.
Created by chemicalweathering of limestone

22. Landslides, mudslides, slump and creep

23. Mudflow and Debris Flood
Mudflow: flowing mixture of water and soil or
regolith that flows rapidly downhill
Lahar: volcanic mudflow
Debris floodor debris flow: very watery
mudflow
Alpine debris avalanche: debris flow on steep
slopes in mountainous regions

24. Hurricanes can bring huge volumes of
water on to the landscape, leading to debris
avalanches and mudslides