Aim: Weathering and Erosion. Weathering The breakdown of the materials of Earth’s crust into smaller pieces.

Aim: Weathering and Erosion

Weathering

• The breakdown of the materials of Earth’s crust into smaller pieces.

1. Physical 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– Upward Expansion of Rock– Temperature changes

Frost Wedging

Frost Heaving

Plant Roots

Friction and Repeated Impact(Stream ABRASION)

Burrowing of Animals

Upward Expansion of Rock due to the releasing of pressure of overlying rock unloading off the surface. (notice the

peeling of the rock) Ex. Granite (Exfoliation…peeling)

Temperature Changes

Part II Chemical Weathering

• The process that breaks down rock through chemical internal changes.

• The agents of chemical weathering– Water– Oxygen– Carbon dioxide– Living organisms– Acid rain

KEY IDEA: Water plus humid and warm environments

• Water weathers rock by dissolving it

Oxygen• Iron (Fe) combines

with oxygen (O2) in the presence of water in a process called oxidation

• The product of oxidation is rust

Carbon Dioxide• CO2 dissolves in rain water and makes

carbonic acid

• Carbonic acid easily weathers Limestone and marble …key mineral is CALCITE

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.

• Made 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.

A BIG KEY is Water Erosion

• Rivers, streams, and runoff

Ice Erosion• Glaciers-Ice moves

and picks up rock

Wind Erosion- mostly in dry climates

Mass Movements

• Landslides, mudslides, slump and creep

landslide clip.mpeg

SOME MOVIES (Brain Pop) PHOTOS

http://glencoe.mcgraw-hill.com/sites/dl/free/0

078600499/164213/00050754.html

http://science.nationalgeographic.com/science/photos/weathering-erosion-

gallery.html

ANIMATION: http://ees.as.uky.edu/sites/default/files/el

earning/module07swf.swf