Transcript Weathering and Erosion PP

Weathering and Erosion
Weathering
• The breakdown of the materials of Earth’s
crust into smaller pieces.
Physical (Mechanical) Weathering
• Process by which rocks are broken down
into smaller pieces by external conditions.
Frost Wedging
Frost Heaving
Plant Roots
Plate Tectonics
Burrowing of Animals
Temperature Changes
Chemical Weathering
• The process that breaks down rock
through chemical changes.
Water
• Water weathers rock by dissolving it
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
Water Erosion
• Water is the most
important erosion agent
and erodes most
commonly as running
water in streams.
• The faster water moves in
streams the larger objects
it can pick up and
transport. The movement
of these materials help to
further erode the rock.
Water erosion
• Water typically flows from
highlands to lowlands. The
source of that water can include
underwater springs, melting
snow or ice caps, or rain.
• Flowing water erodes rock and
creates canyons, valleys, and
stream networks.
Ice Erosion
• Ice erosion is caused by movement of ice,
typically as glaciers. Glaciers can scrape
and break up rock and then transport it.
Wind Erosion
Wind Erosion
occurs when gas molecules
bounce against rocks and other
surface features.
The thinner (less dense) the
atmosphere, the faster the wind
must blow to affect the surface
Planetary Winds
• Wind is gas in motion. Wind can only exist
on planets with atmosphere.
• The three terrestrial planets that have
atmospheres and WIND are Mars Venus
and Earth.
• Which planet requires less wind speed to
cause erosion?
• Mars or Venus (Why?)
Mass Movements
• Landslides, mudslides, Creep, slump
landslide clip.mpeg
• http://www.youtube.com/watch?v=09OvdY
CcEEw&feature=related
Creep
• Creep is the slow movement of sediment
down an incline -- so slow that it
sometimes takes place over several years.
Slump
• In slump, a large segment of sediment
breaks off in one piece rather than in lots
of segments