Mechanical and Chemical Weathering

Temperature Change

Cold causes rock to contract (shrink). Heat causes rock to expand (grow slightly). Repeating over time causes rock to break apart.

Statue details disappearing over time

Chemical weathering - Acid Precipitation

Statue of Liberty turning greenish

Chemical Weathering - Air

Puddles on top of a mountain create pits

Chemical Weathering - Water

Wind

Blows sand and silt against exposed rock eventually wearing away the rock's surface (causes abrasion).

Mechanical Weathering

Breaking down of rocks into smaller pieces using physical forces (examples ice, wind, water, gravity, plants and animals)

Animals

Burrowing animals break up and loosen sediment exposing rock to other forces of weathering.

Water

Causes rock to be broken down by dissolving minerals from a rock over a long period of time.

Sinkhole in someone's yard

Chemical Weathering - Acids in Ground Water

Underground Cave

Chemical Weathering - Acids in Groundwater

Lichens growing on a rock

Chemical Weathering - Acids in Living Things

Rusty cans, nails, etc.

Chemical Weathering - Air

Abrasion

Happens when two different rocks or earth materials grind or scrape against each other

Acids in Living Things

Lichens produce acid that slowly break down rock; roots and decaying plants release acids dissolving minerals and weakening rock.

Burrows/Tunnels underground

Mechanical Weathering - Animals

Rock slide

Mechanical Weathering - Gravity

Broken Rock

Mechanical Weathering - Ice Wedging

Ice in a rock

Mechanical Weathering - Ice Wedging

Cracks in sidewalk by tree

Mechanical Weathering - Plants

Crack in the concrete

Mechanical Weathering - Plants/Ice Wedging

Potholes

Mechanical Weathering - Temperature, ice

Pebbles in the river

Mechanical Weathering - Water

Great Sphinx in desert in Egypt

Mechanical Weathering - Wind

Rock formation in desert

Mechanical Weathering - Wind

Air

Oxygen in the air reacts with iron causing it rust

Chemical Weathering

Process by which rocks break down as a result of chemical reactions (examples include water, acids, air)

Weathering

Process through which rock material is broken down by physical or chemical activity

Acid Precipitation

Rain, sleet or snow that contains a high concentration of acid.

Gravity

Rocks are pulled down and grind against each other during a rock slide, creating smaller and smaller rock fragments. Anytime one rock hits another, abrasion takes place.

Plants

Roots grow into cracks in the rocks, as the roots grow, they press on the sides of the crack, making it wider until it breaks apart (example - tree roots breaking up the sidewalk).

Frost wedging/ice wedging

Water seeps into cracks in rocks during warm weather, when it freezes, the water expands and the ice causes cracks to widen until the rocks break apart. (Potholes are an example.)