Transcript Document
Weathering and Soil Chapter 4 4.1 Rocks and Weathering • Erosion into smaller pieces – Breaking down of rock ___________________ Carrying away/removal – _______________________ of rock particles by: • • • • Wind Water Ice Gravity 4.1 Rocks and Weathering • _____________ Weathering – Breaking down and wearing away of rocks and other substances – Forces involved: • ______________ water • ______________ ice gases • ______________ • ______________ heat • ______________ cold 4.1 Rocks and Weathering Mechanical rock physically broken up into smaller pieces Chemical break down rocks uses chemical changes to break down rock 4.1 Rocks and Weathering • Agents of mechanical weathering – Freezing and thawing • _____________________ frost wedging – Release of pressure – ________________ plant growth – Actions of animals abrasion – ________________ 4.1 Rocks and Weathering • Freezing and Thawing (Frost Wedging) 1. Water seeps into crack and air pockets expands making the crack 2. Water freezes and __________ __________ bigger – Frost wedging causes ____________ and cracks in potholes concrete or blacktop 4.1 Rocks and Weathering • Release of pressure 1. 2. 3. Material is removed from the rock’s surface pressure is reduced ________________________ The release of pressure makes the outside of the rock to _______________in layers like an onion peel and flake 4.1 Rocks and Weathering • Plant Growth 1. __________ of plants grow into spaces or cracks Roots 2. They make the cracks bigger and spreads them apart _____________ 3. As the roots get bigger they pry the spaces or wider open cracks ___________ 4.1 Rocks and Weathering • Actions of Animals 1. Animals _____________ in the ground burrow 2. This _____________________ loosens and breaks up up the soil – Moles, prairie dogs, gophers, some insects 4.1 Rocks and Weathering • Abrasion sand or rocks wear away at 1. Small particles of ______________ exposed rocks 2. Wind, water, or ice carry these particles sandpaper – Works like __________ 4.1 Rocks and Weathering • Agents of chemical weathering Water – ____________ – Oxygen Carbon dioxide – ____________ – Living organisms Acid rain – ____________ 4.1 Rocks and Weathering • Water Dissolving rocks – ______________ – Carry substances that dissolve rocks including: • Oxygen • Carbon dioxide • Other chemicals 4.1 Rocks and Weathering • Oxygen water – Combines with _________ • This is called oxidation rust • This forms ________ – Rust softens rock and makes it crumble and gives it a red-brown color 4.1 Rocks and Weathering • Carbon Dioxide – When dissolved in water it makes a weak acid called _________________ carbonic acid – Carbonic acid weathers rocks like ___________ marble and ____________ limestone 4.1 Rocks and Weathering • Living Organisms weak acids – Plants’ roots produce ___________ dissolve rocks around the – These acids slowly ______________ roots – _________ (plants-like organisms that grow on Lichens rocks) produce weak acids that wear away rocks 4.1 Rocks and Weathering • Acid Rain slightly acidic – Rainwater is ______________ pollution into the – Burning of fossil fuels adds ___________ air with sulfur, carbon, and nitrogen compounds – These make stronger acids in the rainwater – Acid rain falls and ____________ weathers rock rapidly 4.1 Rocks and Weathering • Factors that affect rate of weathering: Type of rock – ______________ • Minerals that make up the rock • Permeability of the rock 4.1 Rocks and Weathering • Factors that affect rate of weathering: Climate – ___________ (average weather conditions) • Chemical reactions occur ________ faster in warmer climates Warmer = faster • ____________________ 4.1 Rocks and Weathering • Factors that affect rate of weathering: – Climate (average weather conditions) • Chemical reactions occur faster in warmer climates • Warmer = faster