Weathering Erosion & Deposition

WeatheringErosion&Deposition

Essential Question? • How does weathering and erosion affect the Earths surface? Footer text here

EssentialQuestion PA? • How does the interaction of air, water and earth shape the surface? Footer text here

Student Objective: • Today I will develop an understanding of how weathering shapes the Earth’s surface. Footer text here

WeatheringThe break down of rocks and minerals due to wind, water, ice, chemical reaction, or biological matter such as plants and animals. Water – Waves crashing into the shore Wind – breaks off sediments leaving a plateau of land called a Mesa Water – When mixed with CO2 or other acids can dissolve rock and create sinkholes Ice or Plant Roots – When either get into a crack they expand or grow, breaking the rock and making the crack larger. Footer text here

Physical Weathering • Process by which rocks are broken down into smaller pieces by physical forces. • Types of Mechanical weathering • Ice wedging • Plant roots • Abrasion • Burrowing of animals (animal action) • Temperature changes (freezing and thawing) Footer text here

Plants and Animals • PLANT ROOTS CAN SPLIT ROCK • Also known as: “Root pry” or “Root action” • ANIMALS DIG HOLES AND BURROW, BREAK UP ROCK

Ice Wedging • PROCESS IN WHICH WATER FREEZES IN THE CRACKS OF ROCK AND WEDGES (PUSHES) IT APART BECAUSE WATER EXPANDS WHEN IT FREEZES. • OCCURS WHERE THERE ARE FREQUENT FREEZES AND THAWS Footer text here

Abrasion • The wearing awayof rock material by grindingaction • Usually caused by sediment in Wind and Water Notice the rounded river rocks Footer text here

How decomposers enrich soil and make it fertile: mechanical weathering . Chipmunks live in dens in the soil and search the litter for seeds and nuts. Plant roots break up the soil and hold it in place. Earthworms break up the soil, making it easier for plant roots to spread and for air and water to enter the soil. They create waste which makes soil more fertile by adding nitrogen. Bacteria are decomposers that break down animal and plant remains and wastes.

Chemical Weathering • The breakdown and decomposition of rock that occurs when minerals arechanged into different substances • (change in composition) • The agents of chemical weathering: • water- water dissolves rock over time • oxygen- combines with iron to form rust (oxidation) • carbon dioxide- dissolves in water to form carbonic acid • living organisms- plant roots secrete acids • acid rain- from the burning of fossil fuels Footer text here

Acid rain (carbonic acid) weathering the details of statues and tombstones Ex: Marble and Limestone

Rate of Weathering • Climate (long term pattern of moisture and temperature) • Weathering rates are faster in warm, wet climates Desert vs. Rainforest

Question????? • Compare and contrast the role of air, water, and plants in chemical versus physical weathering. Footer text here

Essential Question???? • Why does the Earth look the way it does? • How can maps and models be used to understand interactions on earth? Footer text here

Student Objective: • I will develop an understanding of how erosion and deposition shape the Earth’s surface. Footer text here

ErosionThe movement of sediments by wind, water, ice, or gravity. Glaciers – Push sediments down mountains carving through the land Rivers – Carry sediments away carving out canyons Footer text here

Erosion by Rivers • Through erosion a river creates valleys, waterfalls, flood plains, and meanders (loop like bend in a river) • Grand Canyon Formation

Streams and Rivers • Velocity - How fast the water moves • Gradient - The steepness, the slopethat a river or stream travels • Discharge - The amount of water that moves past a certain point in a river in a given amount of time • If there is a steep gradient, high velocity, and a large discharge, then Erosion will be severe! • Rivers have energy to move lots of sediment, and even large boulders.

Gravity’s Effect on Earth’s Surface • Gravity is the force that moves rock and other materials downhill. • Mass movement of rocks or sediments can be fast or slow. • The different type of mass movements caused by gravity include landslides, mudslides, slump, and creep. Footer text here

Erosion-Mass Movement:A large mass of sediment drops down!

Erosion by Gravity Creep is the gradual movement of soil down a slope in response to gravity. This eventually results in a mass downward movement of soil on the slope. Evidence of soil creep includes the formation of step-like ridges along the hillside, leaning walls and telegraph poles, and trees that grow in a curve to counteract progressive leaning.

Question??? • Streams that are located on a steep slope move faster due to gravity. What effect does this have on the amount of rock or soil that these streams can erode? Footer text here

Deposition Sediments carried by wind, water, or ice are dropped (deposited) in a new location. Water – Deposits sand along the shoreline to form barrier islands. Water – Rivers carry sediments downstream and deposit them at the mouth where new land forms. Wind – Blows sand and it builds up in hills called sand dunes Footer text here

Deposition • This can happen in a river when the water slows and creates a new bank, or delta. • The Mekong Delta ( “Nine Dragon river delta”) is the region in southwestern Vietnam where the Mekong River approaches and empties into the sea through a network of distributaries.

Question???? • What are some ways in which plants, small animals, or insects might be affected by moving ice or landslides? Footer text here

Geologic Time Scale • Scientists use the Law of Superposition to determine the relative ages of sedimentary rock layers. • According to the Law of Superposition, in horizontal sedimentary rock layers the oldest layer is at the bottom. Each higher layer is younger than the layers below.

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Question???? • Why is it important for scientist to study past geological process that have shaped the Earth’s surface? Footer text here

Weathering Erosion & Deposition