Weathering

And

Erosion

Weathering

Types

And

Erosion

&

Deposition

Breaking it Down the Real Earth surface!How does Erosion and Deposition Change the Surface of the Earth?

S6E5 d. Tell steps that change rocks and the surface of the Earth.Learning Target: I can explain the Forces that Change the Face of Earth.

Essential Question(s): How does water and wind change the surface of the earth?

Directions: Read EACH slide then decide what information to record… (Some slides may be in red bold letters others underlined)

Weathering• Weathering is simply the chemical and/or

physical breakdown of a rock material--

weathering involves specific processes acting on

rock materials at or near the surface of the Earth

The Different Types of WeatheringThere are many different types of Physical /

mechanical weathering.

Here are a few AGENTS:

•Root Pry

• Exfoliation

• Frost Action

• Wind Abrasion

• Frost action

Root plant action Pry

The tree is growing in the rock and soon the rock will break apart because of the

tree roots.

This is a picture of the Half Dome. The

rock is peeling away from the

mountain in layers just like an onion. This is exfoliation.

Frost Action or ice wedging slowly breaks up this sedimentary rock into unusual shapes.

These rocks have been blasted by wind and sand causing them to become rounded.

WIND ABRASION

Chemical weathering

and AGENTS:

• Acids in Groundwater

• Karst Topography

Living Organisms

This rock is red because of the oxidation of iron in the sediment when the rock was being

formed.

Acid Rain

1908 to 1969

Acid rain has eaten away this limestone statue.

Karst Topography

• A type of landscape in rainy regions where

there is limestone near the surface,

characterized by caves, sinkholes, and

disappearing streams.

• Created by chemical weathering of

limestone

Features of Karst: Sinkholes

Features of Karst: Caves

Living Organisms

• Lichens that grow on rocks produce weak

acids that chemically weather rock

Chemical

Weathering

17

2. Particle Size – Larger particles weather slower and smaller

particles weather at a faster rate.

There are 4 factors that affect the rate of weathering:

1. Surface Area (exposure) - Exposing more surface area will

increase the rate of weathering.

3. Chemical Composition (what a rock is made of) – Certain rocks

and minerals are naturally weaker than others, while others are more

resistant (stronger).

4. Climate – Warmer, moister climates have the most weathering.

Heat & Water speed up all chemical reactions. This is the most

important factor in weathering.

Erosion is the process by which soil and rock are moved from one location to another on the surface by natural processes such as wind or water flow, and then transported and deposited in other locations.

Erosion

There are many kinds of Erosion.

Here are a few AGENTS:

• Wave Action

• Running Water

• Landslides

• Avalanche

•Glaciers

• Slump

•Creep

• Rock Fall

• Mud Flow

What is Erosion? Erosion is defined as removal of rocks

and soil by wind, water, ice and gravity.

Wind, water, ice and gravity are also

known as the agents of erosion and

through erosion, a river creates valleys,

waterfalls, flood plains, meanders, and

oxbow lakes

Water Erosion

Water running downhill is the major agent of

erosion that has shaped Earth's land surface.

The force of a falling raindrop can loosen and

pick up soil particles. As water moves over

land, it carries these particles with it. This

moving water is called runoff, which is water

that moves over Earth's surface.

Wave action is when waves hit the rocks and pieces of rock break off.

In this picture the running water eroded the sides of this canyon and created the V-shaped valleys.

Gravity Erosion-Rock Fall

Gravity Erosion is better known as Mass Movement and

is defined as the transfer of rock and soil down slope by

direct action of gravity without a flowing medium (such

as water or ice). Some of the best examples of Mass

Movement are:

Creep

Rock fall Slump

Landslides Avalanches

Mass Movements

• Landslides, mudslides, slump and creep

landslide clip.mpeg

Slower Faster

This is a picture of a landslide. A type of mass wasting.

In this picture the land has slumped

into the road below.

This is a diagram of creep. The hillside slowly slips over many years from

temperature or water.

This is a picture of an avalanche. It is similar to a landslide with ice and

snow instead of rock.

What type of mass movement is each picture?http://classes.colgate.edu/dkeller/geol101/massw/mass.htm

LANDSLIDE MUDFLOW

SLUMP CREEP

1 2

3 4

Ice Erosion

Glaciers wear down the landscape; by picking up and

carrying debris that moves across the land along with

the ice.

Glaciers can pick up and carry sediment that ranges

in size from sand grains to boulders bigger than houses.

Moving like a conveyor belt or a bulldozer, a single

glacier can move millions of tons of material!

How much erosion takes place is determined by the:

•**Sum (Glaciers are massive!)

•Slope

•Speed

•Surface

IceIce (glaciers) carry sediment.

This is a picture of a glacier which carves out a U-shaped valley where it flows dragging

rocks and boulders along the way.

Mrs. Degl 34

You can identify which agent of erosion transported each sediment by looking at

a few characteristics:

Running Water – sediments that have been transported through

running water appear rounded and smooth and are deposited in

sorted piles.

Glaciers – sediments that have been transported by glaciers appear

scratched, grooved, and are deposited in completely unsorted

piles, because they were dropped during melting. Also, boulders

can only be transported by glaciers.

Wind - sediments that have been transported by wind are appear

pitted (random holes) and frosted (glazed look) and are deposited

in sorted piles. Only very small particles can be transported by

wind.

Gravity – sediments that are transported by gravity are found in

piles at the bottom of cliffs or steep slopes. They appear angular and unsorted.

Mrs. Degl 35

Factors that influence erosional rates (speed) in running

water and glacial ice:

1. Slope (gradient) of the land – as slope increases, the water velocity increases, the particle size that the water can carry also increases, therefore the amount of erosion increases.2. Volume (size of the water or glacier) – as the volume of the water or glacier increases, their velocities increase, the particle size that they can carry also increases, therefore the amount of erosion increases.3. Position within the running water – Water is traveling faster around the outside of turns therefore that is where more erosion occurs. Water is traveling slower on the inside of turns; therefore deposition occurs on the inside.

Deposition

Rock particles that are picked up and transported during erosion will ultimately be deposited

somewhere else

Deposition is the process by which sediments (small

particles of rock) are laid down in new locations.

• Together, Erosion and Deposition build new landforms.

• Deltas

• Canyons

• Meanders

• Floodplains

Water Deposition Deltas – slow river current drops sediment in fan-shaped

pattern at end of river

Sand Bars – offshore deposit of sand, gravel, or shell material

Alluvial Fans

Beaches – deposited sand

Delta

• Where rivers meet the

ocean is called the

mouth of the river.

Soil and dirt carried

by these rivers is

deposited at the

mouth, and new land

is formed. The new,

soil-rich land is known

as a Delta

Mrs. Degl 39

Delta – a fan shaped deposit that forms at the mouth of a

river/stream when it enters a larger body of water. This is seen

under the water. The particles are horizontally sorted.

Mrs. Degl 40

Alluvial Fan - a fan shaped deposit of sediments that forms

when a stream/river flows out of a mountain on to flat, dry plains.

These are not under water and are very visible. This only

happens on the land. You can call it a “land delta”.

Canyons

Canyons are large valleyscreated by a river or stream.

Meander

Meandering streams wander side to side as they constantly

seek out the lowest elevation.

This constant motion creates a series of S-shaped “loops”.

Mrs. Degl 43

Meandering (Curving) River/Stream

Straight Flowing River/Stream

Sediments

are

traveling

the fastest

in the

center

directly

below the

surface.

Erosion

happens

on the

outside of

turns.

Deposition

happens

on the

inside of

turns.

Running

Water

Mrs. Degl 44

Floodplains

• These are low-

lying areas along

the sides of a river

channel that have

regular times of

heavy wate rflow

to cause the river

to spill over and

flood the land.

What did water create in each of these pictures?

DELTA SANDBAR

ALLUVIAL FAN

http://www.school-

portal.co.uk/GroupDownloadFile.asp?file=2160

4

1

2

44

6

1 2

4

53

BEACH

How does this affect us?Humans are constantly

influencing the nature

of our landscapes.

HOUSES, ROADS,

BUILDINGS,

DEVELOPMENTS,

CANALS, etc., all

change the shape and

appearance of the

land.

48

There are 5 ways that man can cause erosion:

1. Forestry – all vegetation of removed,

and without roots, the soil will erode

away.

2. Strip Mining –removing rock cover to

get to the resources below, this causes the

loose sediments to erode away.

3. Construction – the clearing of land to

build buildings/houses also causes all

loose soil to erode away.

4. Improper Farming – not plowing the

land at right angles to slopes causes soil

to erode away.

5. Salting Highways – the salt is washed

off the road to the sides, where it

prevents vegetative growth along the

sides.

Summary please pick ONE

• Use at least two facts from your notes

to explain the question below.

• How does Erosion and Deposition Change the Surface of the Earth?

OR

• How does water and wind change the surface of the earth?

49