WeatheringThe breaking down of the Earth’s crust into smaller
pieces. It is caused by physical, chemical, or biological means.
The Different Types of Weathering
Physical WeatheringProcess by which rocks are broken down into smaller pieces by external conditions.
Types of Physical Weathering Frost heaving and frost wedgingPlant rootsFriction and impactBurrowing of animalsTemperature changes
Root PryThe tree is
growing in the rock and soon the rock will break apart
because of the tree roots.
Temperature • Temperature can produce mechanical
weathering. During the day, the sun’s energy heats a rock’s surface. During the night, the rock’s surface cools. The repeated change from hot to cold may cause the rock to peel or flake layers that are parallel to the rock’s surface. This peeling or flaking is known as exfoliation.
This is a picture of the
Half Dome. The rock is
peeling away from the
mountain in layers just
like an onion. This is
exfoliation.
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
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
Erosion• The process by which water, ice, wind or gravity
moves fragments of rock and soil.• Erosion loosens & transports sediment formed by
weathering.
ErosionThere are many kinds of
Erosion.Here are a few:• Wave Action
• Running Water• Landslides
• Avalanche•Glaciers• Slump
•Creep • Rock Fall• Mud Flow
Erosion Moving water & wind cause changes to existing land forms & create new landforms such as valleys, plateaus, flood plains, canyons, caves or dunes
This is a picture of a glacier which carves out a U-shaped valley
where it flows dragging rocks and boulders along the way.