4.5 Weathering and Erosion Lesson

Weathering and Erosion

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Multiple Choice

What are two types of weathering?

• weathering and erosion

• chemical and physical

Multiple Choice

The process that breaks rocks apart without changing them chemically

• erosion

• chemical weathering

• physical (mechanical) weathering

• acid rain

Water Erosion

Wind Erosion

Plant Growth

Carbon dioxide and Water

Carbon Dioxide and water

​Erosion is the moving of rocks and soil, wind, ice or gravity.

When a glacier moves soil and rocks, this is a kind of erosion.

A landslide is another kind of erosion.

​weathering - the breaking down or wearing away of rocks by wind or water.

​How is weathering happenning here?

​Here we can see erosion happenning. What is causing it?

Gravity - a force that pulls all objects with mass towards each other - things are pulled towards the center of the earth.

Multiple Choice

Is this weathering or erosion?

• weathering

• erosion

Multiple Choice

Is this weathering or erosion?

• weathering

• erosion

​deposit - to put or set something down in a specific place.

Sediment - very small pieces of sand and minerals set down by water, wind or ice.

​The land around The Grand Canyon was laid down over millions of years by sediment being deposited in the area.

How was the Grand Canyon formed?

​The river in the bottom has dug a channel through the layers of rock.

This took 5 or 6 million years to do.

When rain falls the water takes the soil with it, erosion.

Gravity also causes land slides also a form of erosion which expands the sides.

Going down through The Grand Canyon is like going into a time machine.

Multiple Choice

The breaking down of rocks into smaller pieces

• weathering

• vegetation

• erosion

• deposition

Multiple Choice

The weathering and removal of rock and soil

• weathering

• vegetation

• erosion

• deposition

Multiple Choice

A surface feature of the earth's land

• landform

• glacier

• sediment

• delta

​Landforms - a natural feature on the Earth's surface.

Earth's surface is made up of many landforms.

Lake

A lake is a piece of water completely surrounded by land

Hills

Hills are land formations that are similar to mountains. Unlike mountains, however, hills are not peaked on top. Instead, hills have soft, rounded tops. They are made of grass, dirt, and rocks. 

Mountains

Mountains are large rock structures that are steep (rise quickly) and have pointed tops. 

River

A river is a large natural stream of water that flows over land.

Delta

a piece of land in the shape of a triangle or fan made by deposits of mud and sand at the mouth of a river.

Multiple Choice

What landform is this?

• Valley
• Mountain
• volcano

• Island

Multiple Choice

What landform is this?

• canyon

• Mountain
• volcano

• Island

Multiple Choice

What landform is this?

• valley

• Mountain
• volcano

• Island

How does Moving Water Cause Erosion?

• Erosion begins with just a small amount of water

  • Some Water sinks into the ground and some Evaporates

  • The rest flows over the lands surface and moves soil particles

• Moving Water is the major agent of erosion that shapes the lands surface​

Lesson 3.2 | Grade 8 Ohio

Runoff

• Runoff: Flowing water that carries off land particles

  • The more runoff in an area, the more the erosion occurs

  • Five Main Factors can affect the amount of runoff an area sees

    • Amount of rain in the area

    • Vegetation in the area

    • Type of soil

    • The shape of the land

    • How people affect the land

Lesson 3.2 | Grade 8 Ohio

Multiple Choice

What type of glacier covers huge areas of land?

• alpine

• continental

• till

• moraine

Factor 1: The Amount of Rain

• ​Extreme levels of rain or drought alter the soil and land formation

  • High amounts of rain mean more standing/flowing water in an area to move particles

  • Extremely low amounts of rain make soil particles dry and easier to break apart

Lesson 3.2 | Grade 8 Ohio

Factor 2: Vegetation

• Vegetation: Plant life in a given area

  • Plants absorb water from the soil, so the soil can absorb more water before being flooded

  • Plants cover the soil particles, protecting them from water

Lesson 3.2 | Grade 8 Ohio

Factor 3: Type of soil

• Some soil absorbs more than other

  • Rocky soil lets water pass through without absorbing much

  • Soil with small particles like clay collect a lot of water ​

Lesson 3.2 | Grade 8 Ohio

Factor 4: The Shape of the Land

• The direction the land moves changes how water flows

  • Water moves downhill, carrying particles with it

  • Flat basins of land collect water without it moving much

Lesson 3.2 | Grade 8 Ohio

Factor 5: How People Affect the Land

• People deliberately change land in a variety of ways, and change how it produces runoff

  • Removing Vegetation

  • changing the soil type

  • Reshaping land

Lesson 3.2 | Grade 8 Ohio

Stream Formation

• As water flows and erodes the land, it forms different structures

  • Rills: tiny grooves in the soil caused by runoff

    • Dry up very quickly

Lesson 3.2 | Grade 8 Ohio

Stream Formation

• As water flows and erodes the land, it forms different structures

  • Gully: A large groove or channel ​in the soil caused by runoff

    • As water flows through a gully, soil and rocks move with the water and make it larger

    • Gullies tend to dry up a short time after a rainstorm​

Lesson 3.2 | Grade 8 Ohio

Stream Formation

• As water flows and erodes the land, it forms different structures

  • Stream: a large channel of water made up of multiple gullies

    • Rarely Dry up

    • Also called: creeks, brooks

    • Once it grows large enough, it is considered a River

Lesson 3.2 | Grade 8 Ohio

Stream Formation

• As water flows and erodes the land, it forms different structures

  • Tributary: A stream or river that flows into a larger river

    • Watershed: The area that rivers and tributaries collect their water from

Lesson 3.2 | Grade 8 Ohio

Valley

Valleys are low areas between two mountains or hills. A valley can be large or small. It depends on the distance between the two mountains or hills.

Multiple Choice

Which of the pictures is a a hill? Can you explain the difference between that and a mountain?

Multiple Choice

What is a piece of land in the shape of a triangle or fan made by deposits of mud and sand at the mouth of a river?

• Delta

• Ocean

• Hill

• Lake