Weathering and ErosionWeathering and Erosion

55thth Grade Grade

What is weathering?What is weathering?

Physical break up of the rocks on Earth’s surface into Physical break up of the rocks on Earth’s surface into smaller pieces of sand or rock.smaller pieces of sand or rock.

It is a slow occurring process that takes place over It is a slow occurring process that takes place over time. Most weathering takes place at the Earth’s time. Most weathering takes place at the Earth’s surface.surface.

2 types of weathering: mechanical & chemical.2 types of weathering: mechanical & chemical. Mechanical weathering = breaking of larger rocks Mechanical weathering = breaking of larger rocks

into smaller pieces of rock, called sediment.into smaller pieces of rock, called sediment. Chemical weathering = rocks change into other Chemical weathering = rocks change into other

materials.materials.

Mechanical ChangesMechanical Changes Ice (glaciers) – when water freezes it expands. When Ice (glaciers) – when water freezes it expands. When

water trickles down the cracks of rocks, it can break water trickles down the cracks of rocks, it can break the rocks apart when it freezes.the rocks apart when it freezes.

Wind – smoothes and polishes rocks as it strikes the Wind – smoothes and polishes rocks as it strikes the surface.surface.

Water – can break rock into very small pieces. Rocks Water – can break rock into very small pieces. Rocks carried down a swiftly moving river are weathered as carried down a swiftly moving river are weathered as they bump into each other. (strongest weathering they bump into each other. (strongest weathering process)process)

Waves – crash against the shoreline, which causes the Waves – crash against the shoreline, which causes the land to weather away.land to weather away.

Gravity Gravity Plants and animals can help cause weathering as well.Plants and animals can help cause weathering as well.

Chemical changesChemical changes

Water is the main factor that causes chemical Water is the main factor that causes chemical weathering. weathering.

Water can dissolve certain minerals that make Water can dissolve certain minerals that make up rocks. up rocks.

Pictures of WeatheringPictures of Weathering

WeatheringWeathering

WeatheringWeathering

WeatheringWeathering

What causes erosion?What causes erosion? Process of moving weathered bits of rock or dirt from one Process of moving weathered bits of rock or dirt from one

place to another. place to another. 4 types: glaciers, wind, water, and gravity4 types: glaciers, wind, water, and gravity Deposition – dropping of sand and rock carried by wind or Deposition – dropping of sand and rock carried by wind or

water as it slows down or from ice that melts.water as it slows down or from ice that melts. Beaches, sandbars, deltas, and sand dunes form when Beaches, sandbars, deltas, and sand dunes form when

disposition occurs.disposition occurs. Erosion is carried away by moving water, wind, and ice.Erosion is carried away by moving water, wind, and ice. Plants, trees, and shrubs help reduce erosion; therefore, if you Plants, trees, and shrubs help reduce erosion; therefore, if you

live in the mountains it is important to plant some.live in the mountains it is important to plant some. Watch Bill Nye – Erosion in Earth changes folder.Watch Bill Nye – Erosion in Earth changes folder.

GlaciersGlaciers

Glaciers – thick layers of ice. When it slowly Glaciers – thick layers of ice. When it slowly slides down a hill it erodes away the surface slides down a hill it erodes away the surface beneath it. Boulders and rocks, carried in the beneath it. Boulders and rocks, carried in the ice, scrape the rock beneath the glacier carving ice, scrape the rock beneath the glacier carving valleys into mountainsides.valleys into mountainsides.

WaterWater

Moves the most rock on the Earth’s surface.Moves the most rock on the Earth’s surface. Rain carries the soil away as it washes over the land, Rain carries the soil away as it washes over the land,

leaving gullies, valleys, and canyons. leaving gullies, valleys, and canyons. Sometimes mud and dirt can run right into houses, Sometimes mud and dirt can run right into houses,

causing houses to be covered in dirt and mud.causing houses to be covered in dirt and mud. The paths of rivers have changed over the years due The paths of rivers have changed over the years due

to erosion. to erosion. Over time, the river channel becomes wider and Over time, the river channel becomes wider and

deeper.deeper. Carves out the canyon in a V-shaped.Carves out the canyon in a V-shaped.

WindWind

Wind erosion moves back the Earth’s surface. Wind erosion moves back the Earth’s surface. It is not strong enough to carry large rocks.It is not strong enough to carry large rocks.

GravityGravity

Affects all erosional processes.Affects all erosional processes. Pulls sand grains out of the air and rocks off Pulls sand grains out of the air and rocks off

cliffs.cliffs.

Grand CanyonGrand Canyon

Was created due to deposition, uplift, and Was created due to deposition, uplift, and erosion.erosion.

Mostly just uplift and erosion. Mostly just uplift and erosion.

Pictures of ErosionPictures of Erosion

ErosionErosion

ErosionErosion

ErosionErosion

Weathering and Erosion formationsWeathering and Erosion formations

Arches – formed by a combination of erosional Arches – formed by a combination of erosional forces. Ice, rain, and wind continue to weather the forces. Ice, rain, and wind continue to weather the arches in Utah’s Arches National Park.arches in Utah’s Arches National Park.

Butte – formed by running water. Isolated hill with Butte – formed by running water. Isolated hill with steep, even sides, and a flat top. (disposition and steep, even sides, and a flat top. (disposition and uplift cause the layering of buttes) uplift cause the layering of buttes)

Arches, valleys, canyons, and buttes are continually Arches, valleys, canyons, and buttes are continually changing due to the effects of weathering and changing due to the effects of weathering and erosion. erosion.

Watch weathering and erosion video.Watch weathering and erosion video.

EvidenceEvidence

In order to make conclusions about anything In order to make conclusions about anything you must have evidence.you must have evidence.

You can have the actual evidence like fossils You can have the actual evidence like fossils or you can use your observational skills.or you can use your observational skills.

Oldest rocks are found at the bottom of a Oldest rocks are found at the bottom of a mountain and newest rocks found at the top.mountain and newest rocks found at the top.

Extra Credit OpportunityExtra Credit Opportunity

Find examples of weathering and erosion in Find examples of weathering and erosion in UT.UT.

Take pictures or find pictures on the internet.Take pictures or find pictures on the internet. Print the pictures off and be prepared to tell us Print the pictures off and be prepared to tell us

which weathering and/or erosion process which weathering and/or erosion process caused the new land formation. caused the new land formation.

Due: October 8, 2008Due: October 8, 2008