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Mechanical Weathering

Mechanical Weathering. Weathering . The process by which larger rocks are broken down into smaller and smaller rocks Destructive force. Mechanical Weathering. The breaking down of larger rocks into smaller rocks WITHOUT changing the rocks’ minerals. Physical Change.

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Mechanical Weathering

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  1. Mechanical Weathering

  2. Weathering • The process by which larger rocks are broken down into smaller and smaller rocks • Destructive force

  3. Mechanical Weathering • The breaking down of larger rocks into smaller rocks WITHOUT changing the rocks’ minerals

  4. Physical Change • Mechanical weathering is a physical change • Change in size, shape, or state of matter (water boiling and going from a liquid to a gas) • Example: Tearing a piece of paper

  5. Rate of Weathering • Climate- the average weather conditions of an area over a long period of time • Pollution- the dirtying of the environment with water materials or other unwanted substances • Type of Rock- Compare sandstone to granite

  6. Type of Mechanical Weathering Temperature (exfoliation)- rock breaking off or peeling off of a rock. • Example: heat outside causes peeling of rock layers (like a sunburn would peel) Frost (ice wedging)- water that has worked its way into cracks and voids in rock, expanding and wedging the rock apart upon freezing. • Example: potholes

  7. Temperature (Exfoliation) • This is a picture of the Half Dome. The rock is peeling away from the mountain in layers just like an onion. This is exfoliation.

  8. Frost (Ice Wedging) • Frost Action or ice wedging slowly breaks up this sedimentary rock into unusual shapes.

  9. Types of Mechanical Weathering • Organic Activity (root pry)- plant roots in search of minerals and nutrients can work their way into cracks and crevices. • Example: A trees roots breaking the sidewalk apart • Animal Activity- When animals burrow and remove the surface cover and exposing new rock surfaces to the forces of weathering. • Example: Prairie Dog burrowing and bringing up soil to surface

  10. Organic Activity (Root Pry) • The tree is growing in the rock and soon the rock will break apart because of the tree roots.

  11. Animal Activity

  12. Type of Mechanical Weathering • Abrasion- Surface rock that is being broken down by gravity, running water, wind, and ice. • Example: A glacier rubbing against the rock as it moves and grows.

  13. WIND ABRASION • These rocks have been blasted by wind and sand causing them to become rounded. WATER ABRASION ICE ABRASION

  14. Our Land • The land beneath us can be divided into three layers. • The bottom layer is called bedrock. It is made of layers of rocks. As these layers are exposed to air and weather, they begin to change from larger into smaller rock. They turn into smaller pieces and can change physically. These smaller pieces of bedrock make up the second layer which is called the subsoil. The top layer is called topsoil. The rock pieces have become very weathered and may not even resemble the original bedrock. Topsoil also contains organic material like plants. Between the solid particles is either air or water. Our topsoil is affected by the nitrogen cycle.

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