WeatheringWeathering

And And

ErosionErosion

Weathering Types

And

Erosion

&

Deposition

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

S6E5. Students will investigate the scientific view of how the earth’s surface is formed. i. Explain the effects of human activity on the erosion of the earth’s surface. S6CS10. Students will enhance reading in all curriculum areas by: c. Building vocabulary knowledge Demonstrate an understanding of contextual vocabulary in various subjects. Use content vocabulary in writing and speaking. Explore understanding of new words found in subject area texts.

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

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 weatheringand 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 ErosionGlaciers 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 valleys created 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/StreamSediments 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=21604

1

2

4 4 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