weathering, erosion & deposition

By Jeanie Lacob 2014

Landslides

Gravity causes Erosion

How much erosion takes place is determined by

the:

• **Slope

• Speed

• **Surface

Erosion

Erosion is the

of rock material(sediment) fromone to another.

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

Erosion carves the Earth's surface creating canyons, gorges, and even beaches.

__________

______

Erosion

Erosion is the

of rock material(sediment) fromone to another.

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

Erosion carves the Earth's surface creating canyons, gorges, and even beaches.

movement

place

The process by which water, ice, wind or gravity moves fragments of rock

and soil is called?

_____________

The process by which water, ice, wind or gravity moves fragments of rock

and soil is called?.

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

Landslide

landslide clip.mpeg

Landslide – the sudden movement of loose rock and soil down a steep

slope

Mudslide

mudslide – caused by:

Heavy rain or sudden melting of snow (for example as a result of a volcanic eruption)

Wet or dry conditions?

wet

Rockslide

rockslide – caused by:

Loosened rocks suddenly falling

from cliffs

Wet or dry conditions?

DRY

Landslide• Landslide time lapse

slower

faster

Weathering and Erosion

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!

WeatheringIs the process in which rocks areworn away into smaller pieces

Erosion

Erosion is the

of rock material(sediment) fromone to another.

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

Erosion carves the Earth's surface creating canyons, gorges, and even beaches.

movement

place

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• runoff, rivers and, streams

The power of water

. Water is the primary (#1) agent of weathering and erosion on Earth.

Water causes Erosion

How much erosion takes place is

determined by the: • Sum (amount of)

• Slope• Speed

• Surface

Freezing water causes weathering

•

Animation of ice wedging

Describe how ice causes weathering?

Water can break rocks apart when it freezes and _________. expands

Ice causes weathering

Over time, periods of freezing and melting cause the rocks to break.

The expanding ice makes the cracks bigger.

Wind causes weathering

What evidence of weathering do you see

in this picture?

Why wasn’t this mass of land weathered

away?

Plants CAN CAUSE weathering

Growing roots widen cracks and the rock breaks.

Main idea page 83 Section C “I. B”

Plants CAN PREVENT erosion

Other ways to PREVENT erosion

A windbreak (the row of trees) planted next to a field, acts as a shield against strong winds, reducing wind erosion.

Terracing of a hillside slows the rate of water erosion on cultivated slopes.

Heating and cooling can cause weathering

Outer layers of rock can peel off when a forest fire or the Sun heats up the outside of a rock.

When cool rainwater falls on heated rocks , it can cause them to break.

Main idea page 83 Section C “I. D” and “E”

Chemicals can weather rocks

Gases in the air react with iron in some rocks to form rust, which crumbles.

Acid rain weakens rock, causing it to break apart.

Main idea page 83 Section C “I. F”

Glaciers• A glacier is a large

• mass of _________-

• moving ________.

slowice

Glacier

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 ErosionGlaciers 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!

Glacier Bay, Alaska

http://www.geocaching.com

A single large boulder moved by a glacier from one place and deposited somewhere else when the glacier melts is called?

Daggett Rock – Maine's Largest Glacial Erratic

http://www.maine.gov

deposited by the Mendenhall Glacier, seen in the background. Juneau Icefield, Alaska

A long ridge formed by boulders, rocks, and soil carried and deposited by a glacier

http://www.isgs.uiuc.edu

What is the long ridge formed by boulders, rocks, and soil carried and deposited by a glacier called?

Ice Causes Erosion

Grand Canyon

Rivers produce what shaped valleys?

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 geologic time.

Canyons are large valleys created by a

river or stream.

Damage from Dust Storm in Oklahoma, 1936: In the 1930s, agricultural damage, coupled with drought and windstorms, resulted in the severe damage and destruction across the Plains states that became known as the Dust Bowl. (Photo Credit: CORBIS)

Dust storms crackled with powerful static electricity.So much static electricity built up between the ground and airborne dust that blue flames leapt from barbed wire fences and well-wishers shaking hands could generate a spark so powerful it could knock them to the ground. Since static electricity could short out engines and car radios, motorists driving through dust storms dragged chains from the back of their automobiles to ground their cars.

Chapter 7 Lesson 2: Deposition

• Erosion and Deposition can build new landforms such as : headlands and deltas

Deposition

Deposition is the process by which sediments (small particles of rock) are _____ down in new locations. put

Headland

Headland – a _______of land, usually high, that extends into the _______

pointwater

Delta

Deltas have a shallow slope, contain _____

grained sediment (sand and mud)

Flow into a body of __________

(generally).

Nile River Delta

fine

water

Deltas vs. alluvial fans:• Deltas have a • shallow slope, • contain fine-grained

sediment (sand and mud) • flow into a body of water

(generally).

• Alluvial fans have large• coarse-grained sediments

(including boulders), • dominated by debris flows and

large floods; these floods are often flash floods.

• Can flow onto a land surface, or into a body of water

Delta or alluvial fan?

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

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.

Meander formation

Fast-moving water erodes the outer edge of the curve, cutting the river bank.

Slow-moving water deposits the sediment on the inner edge of the curve, forming a sandbar.

Meanderformation

Because _____________ water deposits the sediment on the _________ edge of the curve, forming a sandbar.

Why is the sand being deposited here?

slow-moving

inner

Fast-movingSlow- moving

InnerOuter

• Animation of evolution of a meandering stream

• Lab Activity

Flood plains

• low-lying areas along the sides of a river that during regular times of heavy water flow can be flooded by spill over from the river.

How does water shape the land?

Moving water changes Earth’s surface through:

• ___________ - the process in which rocks are worn away into smaller pieces

• _________ - the movement of rock material (sediment) from one place to another.

• ____________ – the process by which sediments (small particles of rock) are put down in new locations

Deposition

Weathering

Erosion

River System

The Missouri/ Mississippi River System is the largest river system in the United States.

streams

small rivers

medium rivers

Larger rivers

River System

What are the 2 longest rivers in the United States?

Major US Rivers (in order by length):

River, Length in miles (flows into)

1. Missouri, 2,540 miles (flows into Mississippi River)2. Mississippi, 2,340 miles (flows into Gulf of Mexico)3. Yukon, 1,980 miles (flows into Bering Sea)4. Rio Grande, 1,900 miles (flows into Gulf of Mexico)4. St. Lawrence, 1,900 miles (flows into Gulf of St. Lawrence)6. Arkansas, 1,460 miles (flows into Mississippi River)7. Colorado, 1,450 miles (flows into Gulf of California)

Missouri Mississippi

How can people change a River System?

Building dams across the river

Effects of the dam:

1.Flood control

2. Water can be used to make electricity By pushing turbines as it flows through the dam

3. Provides recreation

Hoover Dam near Las Vegas, Nevada

Where do you think the sediment carried by this river is being deposited?

Behind the dam

What does the Mississippi River System form when it flows into the ocean?

An alluvial fan or a delta?

DELTA

bay

A body of water that is partly enclosed by land and has a wide opening.

How does wind action effect our beaches?

The wind can pile up sand into a sand dune

How does wave action effect our beaches?

Seasonal change is illustrated in two postcards that depict the same Santa Barbara beach during summer and winter conditions in 1909 and 1910.

summer

winter

During summer, the waves are milder and deposit sand on the beach

During winter, waves are stronger and erode sand off the beach, storing it in offshore sandbars

Wave action causes the sand to be moved along the beach

Click here for Animation of sand drift along beaches

This picture shows a hillside covered with gullies due to ________ caused by rainfall

A. Deposition B. erosion C. glacier action