Erosion

Day 1

• Define the word Erosion in your own words.

Earth is Change!• The rock that you pass on

the way to school each day and the mountains you see in the distance may look like they've

been there forever, but the truth is that they are slowly disappearing.

• Each time it rains and

every time the wind blows, tiny pieces of sediment get taken

away.

Erosion is Change!• This process, known as

Erosion, is gradually wearing down the

surface of the earth.• Erosion is the process

by which weathered rock and soil are moved  from one place to

another. • Erosion carves the Earth's surface creating canyons, gorges, and

even beaches.

What do you think has caused this rock to look this way?

Rain causes Erosion• When rain falls to the Earth it

can evaporate, sink into the ground, or flow over the land as Runoff.

• When it flows over land, erosion occurs.

• Runoff picks up pieces of rock and "runs" downhill cutting tiny grooves (called rills) into the land. How much erosion takes place is determined by the:

• amount of rainfall • amount of plant growth

• shape of the land • type of rock

Can you list 3 things that effect runoff?

Can you explain what runoff is?

Wind causes Erosion• Wind erosion is a major problem on about 75

million acres of land in the United States.• About 5 million acres are moderately to severely

damaged each year. • Wind erosion physically removes from the field

the most fertile portion of the soil. • Dust obscures visibility and pollutes the air and

water, causes automobile accidents, fouls machinery, and imperils animal and human

health. How do you think farmers feel about wind erosion?

Sand Causes Erosion• The most active agent of

erosion with sand is wind.

• As the wind blows it picks up small particles of

sand/sediment and blasts large rocks with the abrasive particles, cutting and shaping

the rock.• The ability for wind to erode

larger rocks is controlled by:• Size of particles • Speed of wind

• Length of time wind blows • Resistance of rocks

Describe the circumstances in which sand can cause the most

erosion.

Waves Cause Erosion• Waves cause erosion by four different methods:

• Breaking – as the breaking waves hit the shoreline, their force knocks off pieces of

existing rocks. • Forcing water into the cracks of the rocks on the

shoreline • Abrasion- waves carry small rocks and sand

that scrape other rocks • Chemical weathering (salt water breaks down

the rocks) • .

Compare and contrast chemical weathering to abrasion in wave erosion.

Waves Cause Erosion

• Factors that affect the rate of erosion at the shoreline include:

• Size of the waves

• Force of the waves

• Type of the rock

Rain Causes Erosion

Wind Causes Erosion

Sand Causes Erosion

Waves Cause Erosion