Weathering and Erosion

AmoleSpectra of Science

2013

Weathering vs. Erosion

• They work together, but are NOT the same thing

• Weathering is a process that breaks down rock

• Erosion is a process that moves rock

Weathering is like the hammer.

Erosion is like the truck.

Types of Weathering• Physical- breaks down rock without

changing its chemical composition– Frost wedging– Plant roots– Wind– Water

• Chemical-breaks down rock by changing its chemical composition– CO2

– Acid Precipitation– Rust

Frost Wedging• Physical Weathering• Water seeps into cracks• Freezes and expands• Pushes rock apart

Root Pry

• Physical Weathering• Plant roots grow into

rock• Pushes rock apart

Wind Abrasion• Physical Weathering• Wind carrying sand blasts against these rocks

causing them to become rounded

Animal Burrows

• Physical Weathering• Animals create tunnels in rock and sediments

breaking them up

Water Abrasion• Physical Weathering• Running water

repeatedly flows over river rocks making them smooth

Oxidation of Iron• Chemical

Weathering

• This rock is red because of the oxidation of iron in the sediment when the rock was being formed

Acid Precipitation

• Chemical Weathering• Released gases from

burning fossil fuels react with water in the air to create acids

• This acid reacts with limestone to decompose it

1908 1969

Living Organisms

• Lichens that grow on rocks produce weak acids that chemically weather rock

Water• Chemical Weathering

• Water can dissolve minerals found in rocks

Water• Chemical Weathering

• Water can dissolve minerals found in rocks

Carbon Dioxide• Chemical Weathering

• Reacts with water to form acid

Erosion• Process by which rock is moved or

transported• Deposition- process by which material

(sediments) are laid down

Water Erosion• Water transports and then eventually

deposits sediments• Can create deltas, meanders, canyons, and

flood plains

Meander

• S-shaped streams• Wander side to side seeking lowest elevation

Delta• Occur where rivers

meet the ocean• Soil, dirt, sediments

deposited at river mouth

• Creates new soil-rich land

Canyons

• Large valleys created by rivers or streams over time

• Grand Canyon “cut” by Colorado River

Wind Erosion

• Wind picks up and carries sediments to new locations

• Creates sand dunes

Erosion by Gravity

• Gravity causes large masses off rocks and sediments to move from higher locations to lower ones

• Ex: avalanches, land slides, and mudslides

Erosion by Ice

• Glaciers carve U-shaped valleys as they pick up and carry rock fragments along the way

Weathering and

Erosion QUIZ

Frost Wedging

Physical Weathering

Chemical weathering

Rust

Root Pry

Physical Weathering

Water Erosion

Erosion by Glacier

Erosion by Gravity

Erosion by Gravity

Physical Weathering- Frost WedgingErosion- Wind

Chemical Weathering- Acid Precipitation

The marble grave marker has been attacked by acidic rain because of the calcite composition. The grave marker on the right, while old, has not been dissolved because of its granite composition

Physical Weathering-

Tree Pry

Erosion by Gravity