Weathering & Erosion

Weathering and the Rate of Erosion

• Have you ever seen the effects of water, ice, wind, or plants on rock?

• What effects did the water, ice, wind, or plants have?

• Today, you will be learning that water, ice, wind, and plants can cause changes in rocks in several different ways.

Weathering

• Weathering is the breaking down of rocks into smaller pieces called sediment.

• Weathered rock can be reshaped into new landforms.

• When plants grow on rocks, their roots can push in and crack or break the rock.

Sediment

• Sediment is tiny pieces of rock or soil.

• The smallest pieces of sediment are called particles.

• Sediment can be grains of sand, mud, pebbles, minerals, fossils, or decaying plant material.

Sediment

• Rock and soil are broken down into smaller pieces.

• Water, ice, wind, living organisms, and gravity break rocks, soils, and sediments into smaller particles and move them around.

Erosion

• Erosion is movement of rock and sediment from one place to another.

• The landscape changes due to erosion by water, ice, and wind.

Deposition

• Deposition is the layering of sediment into a new place.

• This means that sediment is added to land or a landform.

• Deposition happens when sediment particles are heavy enough to drop from the ice, water, or wind carrying them.

Heating

• Heat is the movement of thermal energy.

• Thawing is changing something from solid to liquid by raising the temperature.

Cooling

• To cool is to lower the temperature.

• Freezing is changing something from liquid to solid by lowering the temperature.

Cooling

• Climate cooling can speed up the rate of erosion at Earth's surface.

• Mountain erosion rates have increased since about six million years ago.

• Cold climate helps create large glaciers. Alpine glaciers play a very big role in the

increase of erosion rates.

Flow

• To flow is to move in a steady way.

• The speed of erosion is related to the energy of flowing water or wind.

• The speed of wind, or places that are windier than others, cause more erosion than places with less wind.

Flow

• Flowing water is a big cause of erosion. It can erode both rock and soil.

• When water is moving very fast, it can pick up large rocks and take them far away.

• When water is moving slowly, it can take small rocks and clay from the ground and move them.

Weather

• Rainfall is the amount of rain that falls from the clouds to the ground.

• Rainfall helps to shape the land and affects the types of living things found in a place.

Weather

• Wind is the movement of air.

• Wind erosion can happen anywhere the soil or sand is not pressed together well.

Ice and Glaciers

• Huge masses of ice called glaciers can cause erosion.

• Glaciers scrape away parts of the rock and ground below them as they creep down mountain valleys.

• When glaciers melt, the scraped rock particles get deposited far from where they started.

Gravity

• Gravity is the force that pulls objects toward each other.

• Gravity pulls down on rock and ice. The falling rocks and ice can hit and break other rocks.

Weather and Gravity

• Water, ice, wind, plants, and gravity break rocks, soils, and sediments into smaller particles and move them around.

• Weathering and erosion shape Earth's landforms over long periods of time through the actions of water, wind, ice, and gravity.