Weathering and Erosion Weathering The breakdown of the

Weathering and Erosion

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

2 Types of Weathering • Physical Weathering • Chemical Weathering

Physical Weathering • Process by which rocks are broken down into smaller pieces by external natural conditions. • Types of Physical weathering – – – – Frost heaving and Frost wedging Plant roots Friction and impact Burrowing of animals Temperature changes Wind rain -humans!

Frost Wedging When water freezes in cracks and expands, causing the cracks to increase in size.

Frost Heaving

Plant Roots As plants grow, their roots also grow. This can cause rocks to break from the force.

Friction and Repeated Impact Water or wind can continuously impact rocks, causing them to breakdown. This is how streams become rivers.

Burrowing of Animals Some animals build homes in the ground. These holes weaken the land.

Temperature Changes

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

Carbon Dioxide • CO 2 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

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: 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.

• Erosion (transport) There are 5 main agents of erosion: 1. *Running Water* 2. Glaciers Weathering has to happen before erosion. The rocks 3. Wind have to be broken into smaller sediments before they 4. Gravity can be eroded away. 5. Man Wind Erosion Glacier

Water Erosion • Rivers, streams, and runoff

Ice Erosion • Glaciers

Wind Erosion

Gravity Mount Rushmore It will not be there forever!! There is a pile of weathered material at the bottom. It is slowly being eroded down hill by gravity.

Man • There are 5 ways that man cause erosion: 1. Forestry – all vegetation of removed, and without roots, the soil will erode away. 2. Strip Mining – removing rock cover to get to the resources below, which causes the loose sediments to erode away. 3. Construction – the clearing of land to buildings/houses also causes all loose soil to erode away. 4. Improper Farming – not plowing the land at right angles to slopes causes soil to erode away. 5. Salting Highways – the salt is washed off the road to the sides, where it prevents vegetative growth along the sides.

Mass Wasting • Landslides, mudslides, slump and creep landslide clip. mpeg

Landslide- Downslope movement of rock, soil, and mud. Mudslide- rapid downslope movement of a mixture of water, rock, and soil Slump- A type of landslide in which a mass of rock breaks away along a curved surface and rotates more or less intact downslope. Creep- a slow moving landslide

Deposition – the process where sediments are released/dropped by their agent of erosion. Most deposition happens in standing/still bodies of water (oceans/lakes). Deposition is caused by the slowing down (loss of kinetic energy) of the agent of erosion.