Weathering And Erosion Weathering And Erosion

Weathering The breaking down of the Earth’s crust into smaller pieces Weathering The 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 Weathering The Different Types of Weathering Process by which rocks are broken down into smaller pieces by external conditions. Types of Physical Weathering Frost heaving and frost wedging Plant roots Friction and impact Burrowing of animals Temperature changes

Frost Wedging

Frost Heaving

Frost Action or ice wedging slowly breaks up this sedimentary rock into unusual shapes.

Root Pry The tree is growing in the rock and soon the rock will break apart because of the tree roots.

Plant Roots

Friction and Repeated Impact

Burrowing of Animals

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.

Temperature Changes

This is a picture of the Half Dome 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.

These rocks have been blasted by wind and sand causing them to become rounded. WIND ABRASION

Chemical Weathering The process that breaks down rock through chemical changes. The agents of chemical weathering Water Oxygen Carbon dioxide Living organisms Acid rain

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

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

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

Acid rain has eaten away this limestone statue.

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: Caves

Features of Karst: Disappearing Streams

Features of Karst: Sinkholes

Erosion The process by which water, ice, wind or gravity moves fragments of rock and soil. Erosion loosens & transports sediment formed by weathering.

There 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

Colorado River as it winds its way through the Grand Canyon.

Grand Falls, near Leup, Arizona

Water Erosion Rivers, streams, and runoff

Wave action is when waves hit the rocks and pieces of rock break off.

In this picture the running water eroded the sides of this canyon and created the V-shaped valleys.

Ice Erosion Glaciers

This is a picture of a glacier which carves out a U-shaped valley where it flows dragging rocks and boulders along the way.

Wind Erosion

Mass Movements Landslides, mudslides, slump and creep

This is a picture of a landslide. A type of mass wasting.

This is a picture of an avalanche This is a picture of an avalanche. It is similar to a landslide with ice and snow instead of rock.

Mudslide

This is a diagram of creep This is a diagram of creep. The hillside slowly slips over many years from temperature or water.

Creep

In this picture the land has slumped into the road below.