Rocks and Weathering What is Weathering Process of
- Slides: 16
Rocks and Weathering
What is Weathering? • Process of breaking down rock into smaller particles • Forces of weathering • Heat and Cold • Oxygen and Carbon dioxide • Water and ice
What is Erosion? • Process of removing rock particles • Forces of erosion • • Water Wind Ice Gravity
What is Uniformitarianism? • theory that changes in the earth's crust during geological history have resulted from the action of continuous and uniform processes. • Charles Lyell • Rain erodes mountains • Magma pushes them up • The Earth’s changes are slow processes that occur over time.
What is Mechanical Weathering? • Process that physically breaks rocks into smaller pieces • • • Freezing and thawing Plant growth Release of pressure Acts of animals Abrasion
Mechanical Weathering Ice wedging 1. 2. 3. 4. 5. 6. Water seeps into rock Temperature cools Water freezes and expands Deepens the crack Ice melts Process repeats
Mechanical Weathering Plant growth Vascular plant forces or wedges itself into cracks present on the rock and forces the crack to open
Mechanical Weathering Abrasion Scraping of a rock surface by friction between rocks and moving particles during their transport by wind, glacier, waves, gravity, running water or erosion.
Mechanical Weathering Acts of Animals • Many animals, such as these Piddock shells, bore into rocks for protection either by scraping away the grains or secreting acid to dissolve the rock.
Mechanical Weathering Release of Pressure • Surface material is removed by erosion • Pressure pushes up on the rock • Layers of rock break off to release the pressure
What is Chemical Weathering? • Process that breaks rocks through chemical changes • • Water Oxygen and carbon dioxide Living Organisms Acid Rain
Chemical Weathering Water • Dissolves salts and reacts with minerals
Chemical Weathering Living organisms • Plants that root and grow on rocks produce weak acids that break down the surface
Chemical Weathering Oxygen • Oxidation: the process when iron in a rock reacts with oxygen to form rust
Chemical Weathering Carbon dioxide • Carbon combines with water to form a weak acid (carbonic acid) Acid Rain • Burning of fossil fuels produces carbon monoxide, sulfur dioxide, and nitrogen oxide…. all of these combine with water to for weak acids
What determines how fast? 1. Type of Rock • Minerals that make up the rock determine rate of weathering • Permeable rock weather faster 2. Climate • Wet climates weather faster • Warmer climates weather faster