Download Weathering & Erosion

Soil - The product of weathering
 Soil-
rocks, minerals (mainly sand and
clay), and organic material (regolith and
organic matter)
 Soil forms layers of different
characteristics called horizons.
Weathering
Weathering is the process that produces
change in the surface of rocks exposed to the
atmosphere and/or hydrosphere.
The breakdown of the materials of the
Earth’s crust into smaller pieces
Two Types OF Weathering:

Physical weathering is
breaking rock by
force.
ex: hitting, scratching,
cracking

Chemical
weathering is where
the rock material is
changed into
another substance
by reacting with a
chemical.


Frost action
(ice wedging)-
1. Water seeps into small
cracks in rocks.
2. When the water freezes it
expands creating great
pressure.
3. The crack widens and
allows water to seep deeper
into the rock.
Frost Wedging

Plant action-
1.
Tiny root hairs seek out small
cracks and pits in rock.
2. Once the root hairs find a
place they grow and expand.
3. The expansion causes great
pressure and cracks the rock.
Plant Roots

Exfoliation
1.
2.
3.
Rocks formed deep in the
Earth are made under high
pressure.
When the pressure is
released the rocks expand
& crack.
May also be caused by
alternate heating and
cooling of rocks by
weather conditions.

Abrasion- rubbing by
other rocks.
Friction and Repeated Impact

OxidationOxygen in the
atmosphere
chemically
reacts with
minerals.
ex.: rusting of a
nail

Water
(hydrolysis)
Minerals are
dissolved in
water.
ex.: Halite,
calcite

Acid- Carbonic
acid:
C02 dissolves in
rain water
forming a weak
acid.
Acid Rain:
Sulfur Dioxide
in the
atmosphere
dissolves in
rain water
forming a
strong acid
(sulfuric acid).
 Wanna hear
how acid rain
was discovered?

Rates of weathering will be
influenced by:
Surface area exposed - weathering
occurs on the surface. More surface
exposed, the faster the weathering will
occur.
A full, solid block has
the least surface area.
The interior is safe
from exposure.
A smashed piece has
greatest
surface area exposed.
The interior can now be
attacked.
Rates of Weathering will depend on:
 Mineral composition- some
minerals
are more resistant than others.
– ex.:Quartz is resistant to chemical and physical
weathering.
Where is the rock more resistant to
weathering?
Where is the rock least resistant to
weathering?
You might also see it like this…
You might also see it like this…
Rates of Weathering will depend on:
 Climatic
Conditions:
Cold and/or dry climates favor physical
weathering.
Warm and wet climates favor chemical
weathering.
Frost action works best in areas where the
temperature fluctuates wildly.
Chemical Weathering
 The process that breaks down rock through
chemical changes.
 The agents of chemical weathering
Water
Oxygen
Carbon dioxide
Living organisms
Acid rain
Oxygen
 Iron combines with
oxygen in the presence
of water in a processes
called oxidation
 The product of oxidation
is rust
Carbon Dioxide
 CO2 dissolves in rain water and creates carbonic
acid
 Carbonic acid easily weathers limestone and
marble
Living Organisms
 Lichens that grow on rocks produce weak acids
that chemically weather rock
Acid Rain
 Compounds from burning coal, oil and gas react
chemically with water forming acids.
 Acid rain causes very rapid chemical weathering
Karst Topography
 A type of landscape in rainy regions where there is
limestone near the surface, characterized by caves,
sinkholes, and disappearing streams.
 Created by chemical weathering of limestone
Features of Karst: Sinkholes
Features of Karst: Caves
Features of Karst: Disappearing
Streams
Erosion
 The process by which water, ice, wind or gravity
moves fragments of rock and soil.
Water Erosion
 Rivers, streams, and runoff
Ice Erosion
 Glaciers
Wind Erosion
Mass Movements
 Landslides, mudslides, slump and creep
landslide clip.mpeg