Weathering

W-E-D Cycle ESRT PAGE 6 The water cycle aides in the Weathering-Erosion-Deposition Cycle

Weathering Weathering: The breaking down of material at or near the Earth’s surface

Physical Weathering A. Physical (Mechanical) Weathering: Changes in the size and/or shape of a rock without changing the rock’s composition

1. Frost Wedging: Water in the cracks of rocks freezes -> volume of the water increases->makes cracks larger->water melts & evaporates ->more rock is exposed-> rock begins to break apart

Physical Weathering 2. Plant Action: Tiny root hairs seek out the breaks in rocks ->roots grow and expand causing greater pressure -> breaks the rock further

3. Exfoliation: Peeling away of large sheets of loosened materials at the surface of a rock due to changes in pressure or temperature

Abrasion 4. Abrasion: The physical wearing down of rocks as they rub or bounce against each other. Five Natural Agents of Abrasion Flowing water Moving ice Waves Winds Gravity

Physical Weathering in Action Visualization

In Your Own Words (10 mins) Write the definition of physical weathering in your own words Draw 4 boxes In each box, define each type of physical weathering in your own words, or draw an illustration of what happens during each type of weathering

Chemical Weathering B. Chemical Weathering- Changes in the mineral composition of a rock thereby forming new substances. Oxidation: Occurs when oxygen interacts chemically with minerals. The rusting of iron is an example of oxidation.

Hydrolysis/Water: Occurs when there are chemical reactions between water and minerals

A Famous Example

Dissolution/Acid 3. Dissolution/Acid: Occurs when minerals are “dissolved” over time- surface has a ‘sugary’ feel when touched. Acid rain and carbonic acid are examples of agents of dissolution.

Chemical Weathering in Action Chemical Weathering Visualization

In Your Own Words (10 mins) On the same paper as physical weathering, but in a separate area, write the definition of chemical weathering in your own words Draw 3 boxes In each box, define each type of chemical weathering in your own words, or draw an illustration of what happens during each type of weathering

Gravestone: Shale

Gravestone: Granite

Gravestone: Sandstone

Gravestone: Marble

Rates of Weathering Rates of weathering will be influenced by… 1. Exposed surface area- weathering occurs on the surface. The more surface exposed, the faster weathering will occur.

Rates of Weathering 2. Mineral composition- some minerals are more resistant than others. For example, quartz is resistant to chemical and physical weathering.

The more resistant a mineral is to weathering, the more time it takes to wear down the material.

Granite vs. Limestone

Rates of Weathering Climatic conditions- Cold and/or dry climates favor physical weathering. Warm and wet climates favor chemical weathering.

Frost wedging works best in areas where the temperature changes often- going from below freezing to above freezing regularly