Weathering Physical/ Mechanical Weathering The breakdown of the materials of Earth’s crust into smaller pieces. Process by which rocks are broken down into smaller pieces by external conditions (wind, water, ice…) Weathering & Erosion

5 Types of Physical weathering 1.Frost heaving/wedging: water in cracks, freezes, & expands 2.Plant roots: grow in cracks causing the rock to break 3.Friction & impact: rocks breaking rocks 4.Burrowing of animals 5.Unloading: overlying rock eroded away creates exfoliation domes.

Chemical Weathering The 5 agents of chemical weathering The process that breaks down rock through chemical changes. 1.Water weathers rock by dissolving it 2.Oxygen combines with iron and forms rust 3.Carbon dioxide dissolves in rain water and creates carbonic acid ◦ Carbonic acid easily weathers limestone and marble

4.Living organisms ◦ Lichens that grow on rocks produce weak acids that chemically weather rock 5.Acid rain ◦ Compounds from burning coal, oil and gasoline react chemically with water forming acids in the clouds and are released when it rains ◦ Acid rain causes very rapid chemical weathering

Factors that affect weathering  Climate: Warm and wet  Surface area  Chemical composition of rock

Erosion 4 Types of Erosion The process by which water, ice, wind or gravity moves fragments of rock and soil. 1.Water: Rivers, streams, and runoff move soils, rocks and sediments around 2.Glaciers moving across the landscape ◦ rocks & boulder moved from place to place ◦ the glaciers carve into the land

3.Wind removing the different surfaces from one place and depositing it in another 4.Mass Movement of Land ◦ Landslides ◦ Mudslides ◦ Slump: when part of a hill moves a short distance down a hill) ◦ Creep: slow movement of land down a slope

 Which rock layer appears to be the least resistant (weakest)?  Which rock layer appears to be the most resistant (strongest)?  Resistant rocks usually form steep cliffs and waterfalls, by sticking out further than the lower layers)?

Deposition  the process whereby these sediments are released by their transporting agents (dropped). 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.