Presentation on theme: "WEATHERING AND EROSION Rock Cycle WEATHERING I. Weathering - The breakdown of rock due to exposure to the atmosphere, weather, plants, and animals."— Presentation transcript:
WEATHERING AND EROSION
WEATHERING I. Weathering - The breakdown of rock due to exposure to the atmosphere, weather, plants, and animals. A. Mechanical Weathering (Physical Weathering) - Rock is split or broken into smaller material without changing its composition. B. Chemical Weathering – Process by which rocks break down as a result of chemical reactions.
Mechanical (Physical)Weathering §1. Ice wedging (Porus, rocks with cracks (ice heaving/Frost Action) §2. Wetting and drying (for clay containing rocks) §3. Plants (lichens, mosses, shrubs, trees) §4. Exfoliation (the peeling away of surface layers) due to the relief of pressure from rocks above it. §5, Expansion / Contraction (Temperature) §6. Abrasion- process of breaking down by means of friction
ABRASION BY WATER
Abrasion – wears down or rounds
ABRASION BY WIND
MECHANICAL WEATHERING Was once solid rock
Exfoliation – causes rock to sheet or flake off
Barrel cactus – breaking through rock to grow
WEATHERING B. Chemical Weathering - Break down of rocks when the rock minerals are changed to different substances.
Chemical Weathering §1. Hydrolysis - chemical reaction with water and other substances (feldspar, hornblende, augite) these combine to form clay. §2. Oxidation - chemical reaction with oxygen and other substances. (Iron bearing substances), (red soil in Carolina & Virgina) §3. Carbonic acid/Carbonation - Carbon dioxide dissolves in H2O to form carbonic acid. (found in soda), P,Na,Mg and Ca (forms caves) §4. Acid Rain - sulfur from cars and coal/oil plants §5. Plants/Animals (Lichens) - produce rock dissolving acids
Details worn away by chemical weathering
Hydrolysis -Reaction of any substance with water
Chemical Weathering- Water molecules "pull" apart a mineral (dissolve it)
Plants can grow on rocks and produce weak acids that can break down rock.
Organic Weathering Lichen breaking down rock
Bird dropping weathering §
RATES OF WEATHERING II. Rates of Weathering 1. The rocks themselves - Igneous and metamorphic most resistant, sedimentary least resistant because of pores. 2. Surface Area – More surface area = faster weathering 3. Climate - Warm and wet = chemical weathering Cold and Dry = mechanical weathering 4. Topography
Weathering §Get on the online book and go to chapter 14. §Select the visual concepts and watch the clips on physical and chemical weathering.
EROSION IV. EROSION- The breakup and removal of rock by moving natural agents (gravity, glaciers, wind, water) A. Water Erosion 1. Rain a. Sheet wash - thin sheets of soil removed prevent by - grass, continued plowing, crop rotation, strip crop, terraces b.Gullying - valleys in sloped land - farms 2. Running water - most effective agent of erosion a. stream, river, creek b. Stream abrasion - grinding away of rock from bed or bank. c. The faster the river moves = more stuff it can carry
EROSION B. Wind Erosion - just as water; only less powerful 1. Abrasion - wearing down of particles 2.Deflation - removal of loose particles by wind - the most important effect by wind 3. Dunes - sand piled up, moved by wind C. Glaciers – most powerful agent of erosion
Arches National Park Wind abrasion
EROSION IV. EROSION- The breakup and removal of rock by moving natural agents (rivers, glaciers, wind, water) A. Mass movements - Earth material down a slope caused by gravity. 1. Creep - Very, Very slow down slope movement of soil. (water in soil adds to it) a. Talus - Loose rock fragments at base of cliffs 2. Landslides - sudden movement of bedrock or loose rocks down a cliff. 3. Slumps - small landslides on hills 4. Mudflow - fast movement of water saturated clay and silt. 5. Avalanche
Landslide – mass movement
Landslide – mass movement
The Colorado River weather and eroded way for 1,000s of years