Weathering DEFINITIONS WEATHERING Brainstorm 1 What is it

Weathering

DEFINITIONS WEATHERING - Brainstorm: 1) What is it? 2) What can cause it? 3) How does weathering change the surface of the Earth? Possible Causes:

WEATHERING • Weathering= the breaking down of rock into smaller and smaller pieces. Is weathering constructive, destructive, or both? Why? -Weathering is destructive- it “tears down” rocks and landforms.

2 Types of Weathering Brainstorm 1) What can cause each type of weatheri ng? WEATHERING 1) Mechanical 2) Chemical Breaking down rocks by physical means Chemical breakdown of rock and minerals into new substances Possible causes:

MECHANICAL WEATHERING 1. ANIMALS Little animals also help weathering by burrowing and digging through the ground.

MECHANICAL WEATHERING 2. Ice Wedging – when water gets into cracks of a rock, freezes & thaws over & over again & splits the rock

MECHANICAL WEATHERING Ice

MECHANICAL WEATHERING 3. PLANT GROWTH • Roots of plants also push into the rocks and break them apart. They act like wedges and push the rocks apart.

MECHANICAL WEATHERING 4. RELEASE OF PRESSURE- as erosion moves sediment from the surface, pressure is reduced. The outside of the rock begins to flake off

MECHANICAL WEATHERING NONLIVING CAUSES 5. Abrasion- sediments carried by wind, water, or ice wear away rock by hitting & scraping against other rock

Abrasion Wind • sandstone shapes eroded by coastal winds Sandblasting

Abrasion WATER - rubs fragments against each other and wears away the surface of the rock by abrasion. – The faster the water, the greater the erosion

Abrasion • Ice- Glaciers –The glacier gouges out chunks of rock and leaves scratches on the rock called striations

CHEMICAL WEATHERING • CHEMICAL WEATHERING the chemical breakdown of rock and minerals into new substances

CHEMICAL WEATHERING Water is considered to be the universal solvent. It dissolves many things – including rock • Over time, water can break down even hard rock like granite

CHEMICAL WEATHERING 2) Oxygen Oxidation (rust) is a chemical reaction in which an iron combines with oxygen.

CHEMICAL WEATHERING 3) Carbon Dioxide (CO 2) -CO 2 mixing with water creates Carbonic Acid that slowly dissolves limestone. (Acid in groundwater) -Caves

CHEMICAL WEATHERING 4) Living Organisms Acids from decaying plants or fungi such as lichens breaks down rocks

CHEMICAL WEATHERING 5. ACID PRECIPITATION is rain or snow that contains more acids than normal due to air pollution. The acid “dissolves” and “eats away” the rock

WEATHERING How does weathering change the surface of the Earth?

Mechanical Weathering Living Plant Animal Nonliving Ice (glacie rs) Roots of plants also push into the rocks and break them apart burrowing and digging through the ground -water gets into cracks of a rock, freezes & thaws over & over again & splits the rock -scratches on the rock called striations Wind wears away the surface of the rock by abrasion Water rubs fragments against each other and wears away the surface of the rock by abrasion.

Chemical Weathering Living Plants Acids from decaying plants or fungi such as lichens breaks down rocks Nonliving Water universal solvent. It dissolves many things – including rock Acid rain or snow that contains more acids than normal due to air pollution. -acid “dissolves” or “eats away” the rock Groundwater CO 2 mixing with water creates Carbonic acid that slowly dissolves limestone Oxidation chemical reaction in which an element combines with oxygen to form an oxide

FORCES THAT CAUSE Weathering 1) Mechanical Living Plants Nonliving Ice - (Glaciers) 2) Chemical Living Plants Nonliving Water Wind Acid rain Groundwater Water Oxidation Animals

Interactive Weathering • How are materials from the earth broken down?