True or False: The Earth’s surface

has stayed the same for

thousands of years

True or False: The Earth’s surface

has stayed the same for thousands of

years

The Earth’s surface is always

changing!

Weathering – Breaks down

Erosion -moves

Deposition –deposits / builds

Weathering, erosion, and deposition act together in a

cycle that wears down and builds up Earth’s surface

Earth’s Changing Surface

Weathering

The breakdown of Earth’s crust into smaller

pieces.

Must occur before erosion can happen

No movement usually occurs.

Sediments- naturally occurring material that is broken down by processes of

weathering; small/tiny pieces of rock

the process of breaking down Earth’s surface into smaller pieces – similar to a physical change

Physical/Mechanical

Weathering

Physical Weathering -- The steep walls here were carved out by moving water

Palo Duro Canyon in the High Plains Eco-Region

Causes of Physical

Weathering

Enchanted Rock in the Llano Uplift Eco-region

Exfoliation-warming and cooling of rocks over time causes rocks to peel into sheets

1.Water

2.Ice

3.Wind

4.Gravity

5.Organisms

Chemical Weathering

This cave was formed by slightly acidic water

dissolving the limestone

Chemical weathering occurs when chemical reactions dissolve the minerals in rocks or changes them into

different minerals (rusting, acid breakdown, etc)

Causes of Chemical

Weathering

Natural Bridge Caverns in Texas

1.Oxidation

2.Hydration

3.Carbonation

Let’s compare

Please draw a Venn diagram and compare chemical and physical weathering.

How are they similar/different?

Water causes weathering

What evidence of

weathering do you see

in this picture?

Wind causes weathering

What evidence of

weathering do you see

in this picture?

Why wasn’t this mass

of land weathered

away?

Ice causes weathering

Describe how ice

causes weathering?

Erosion

The process by which water, ice, wind or

gravity move sediments.

What evidence of

erosion do you see in

this picture?

Erosion is Movement of

Sediment!• Erosion is the

process by which weathered rock and soil (sediment) 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?

Erosion is Movement of

Sediment!

The intensity of erosion is determined

by the 4 S’s:

• Sum (amount)

• Speed

• Slope

• Surface

Wind Erosion

• 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.

Wind Erosion

Water 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.

Water Causes Erosion• runoff, rivers, and streams

Water causes Erosion

How much erosion

takes place is

determined by the:

• Sum (amount)

• Slope

• Speed

• Surface

Can you act increasing

and decreasing the

four S’s?

Ice Causes Erosion

Glaciers wear down the

landscape; by picking up and

carrying debris that moves

across the land along with

the ice.

Ice Causes Erosion

Glaciers can pick up and carry sediment that ranges in size from sand grains to boulders bigger than houses.

Moving like a conveyor belt and a bulldozer, a single

glacier can move millions of tons of material!

Ice Causes Erosion

How much erosion

takes place is

determined by

the:

• **Sum (Glaciers are

massive!)

• Slope

• Speed

• Surface

Gravity is the force that moves

rock and other materials

downhill.

Gravity causes Erosion

Gravity causes erosion

landslide clip.mpeg

Creep, Slump, Landslides, Mudslides, and Avalanches.

These are examples of mass movement

(or called mass wasting)

Slower Faster

Gravity causes Erosion

How much erosion takes

place is determined by

the:

• Sum

• **Slope

• Speed

• **Surface

Bare Slopes vs. Vegetation Stabilized

Slopes

How do weathering, erosion and depostion impact

each side of the “hill”?

Bare Slopes vs. Vegetation

Stabilized Slopes

• Mudslide danger• Loss of topsoil

• Clogged storm drains• Flooding problems• Expensive clean up

• Eroded or buried house foundations

Bare Slopes vs. Vegetation Stabilized Slopes

• Mudslide danger• Loss of topsoil

• Clogged storm drains• Flooding problems• Expensive clean up• Eroded or buried

house foundations

• Soil in place• Less clean up

• Minimum erosion• Protection

for housefoundations

Plants CAN CAUSE weathering

Plants CAN PREVENT erosion

ErosionGalveston Texas before/after Hurricane Ike

Deposition

Deposition is the process by which sediments are deposited in new locations.

• Together, Erosion and Deposition build new landforms.

Delta

Soil and dirt carried by these rivers is deposited at the

mouth (where rivers meet the ocean), and new land

is formed. The new, soil-rich land is known as a

Delta

Canyons

This simple animation provides

you with a visualization of how the

Colorado River has "downcut"

into the rock layers of the Grand

Canyon.

How long it took to carve the

Grand Canyon is debated by

geologists.

Some estimates are between 6

and 8 million years, which is very

recent by comparison.Canyons are large

valleys created by a

river or stream.

Meanders

Meandering streams wander side to side as they

constantly seek out the lowest elevation.

This constant motion creates a series of S-shaped

“loops”.

Meanders - Extra Info

Stream Velocity varies from one side to the other side

of the “S”, resulting in erosion in some places and

deposition of sediments in others.

Floodplains

• Floodplains are an area

of land that is prone to

flooding.

• These are low-lying

areas along the sides of

a river channel that have

regular times of heavy

waterflow to cause the

river to spill over and

flood the land.

Look at the picture of Galveston above, what do you think will happen to this land if another hurricane hits the Galveston coast? Explain each component and how will the island be effected.

WED