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.)