erosion new

EROSION:•TRANSPORT OF SEDIMENTS

AND DEPOSITIN

G THEM

ELSEWHERE

EROSION IS DRIVEN BY THE FORCE OF

EROSION IS DRIVEN BY THE FORCE OF

GRAVITY

THE AGENTS OF EROSION ARE:

RUNNING WATERWINDMOVING ICE (GLACIERS)

Each Agent of Erosion Produces

it’s Own Characteristic

shape and Texture in the

Sediment :

ROUNDS ANDSMOOTHESTHE ROCK SURFACEALSO MAKES ITSMALLER

WIND BLOWN SEDIMENTSFROST AND PIT THE ROCKSURFACE

SMALL SEDIMENTS IN THE GLACIER POLISHES & SMOOTHES THE ROCK SURFACE

LARGE SEDIMENTS SCRATCH AND STRIATE THE ROCK SURFACE

FALLEN ROCKS ARESHARP &ANGULAR

RUNNING WATER

The primary agent of erosion is:

Colorado River

Grand Canyon

Niagra Falls

EROSION BY WATER:

PARTICLES ARE CARRIED IN SEVERAL WAYS DEPENDING ON THEIR

SIZE

THREE ways

streams transport sediment:

SEDIMENTS IN SOLUTION:

DISSOLVED IONS

examples :

•Salt•calcite

Dissolved ions in solution

SEDIMENTS IN SUSPENSION:

COLLOIDS

Can you think of examples :

•SILT•CLAY

SEDIMENTS ROLLED AND

BOUNCED: LARGE SEDIMENTS dragged along the bottom

VELOCITY OF A STREAM

DEPENDS ON:SLOPE (GRADIENT) AND

DISCHARGE•volume of water

Water movesfaster on the

outside ofa bendEROSION

Water movesslower on the

inside ofa bendDEPOSITION

LABEL YOUR DIAGRAM

(EROSION) & (DEPOSITION)

EROSION

DEPOSITION

Erosion occurs

at points

Depsosition occurs

at points

B & E

A & F

A B

C

D

FE

B

C D

E F

Maximum erosion

occurs where there

is maximum

_____________

On a straight path

the maximum velocity is in the ___________

below the ____________

centersurface

velocity

EROSION OCCURS AT THE OUTSIDE

DEPOSITION OCCURS AT THE INSIDE

THE MOVEMENTOF THE WATERCAN EVENTUALLYFORM ANOXBOW LAKE

SEDIMENTS LEFT BEHIND BY

STREAMS AND WIND ARE ________ SORTED

dropped off in size order

CALCULATE THE MINIMUM VELOCITY

OF A STREAM NEEDED TO CARRY

A PEBBLE:

(SEE REF. TABLE PAGE 6)

APPROXIMATELY 50 CM/SEC

WHAT IS THE MINIMUM VELOCITY NEEDED TO CARRY A BOULDER? 200 CM/SEC

SORTING

WIND:

EROSION BY WIND OCCURS PRIMARILY

IN:

•DRY CLIMATES

The particles transported (eroded) by

wind are_________Sorted

Severe draughts in the mid-west during the 1920’s and 30’s caused this area to be known as the “Dust bowl”

Glacial Erosion:•When more snow in winter accumulates than _______ in the summer the snow at the bottom turns to _________.

meltsice

gravity

advance

•If it becomes thick enough, it’s weight will cause it to move under the pull of___________.

•This is called a glacial _________

1.Glaciers create U- shaped valleys

Characteristics of Glacial Erosion:

escarpment

U-shaped valley

Advancing glacier

Retreating glacier

Long Island Sound

South Shore

North Shore

2. Sediments left behind by glaciers are

STRIATIONS SHOW THE DIRECTION OF MOVEMENT OF THE GLACIER

polished& striated (scratched)

3. SEDIMENTS LEFT BEHIND BY

GLACIERS ARE:

UNSORTED

Advancing glacier

MORE SNOW FALLS THAN MELTS

Retreating glacierICE BEGINS TOMELTDUE TO CLIMATE CHANGE

Terminal end of advancing glacier

Latest advance

Melt-water carrying sortedSediment toward the ocean

THE SOUTH SHORE OF LONG ISLAND

F

FOUND ON THE NORTH SHOREOF LONG ISLAND

FASTEST VELOCITYIS AT THE CENTEROF THE VALLEY

Some glacial features include:

escarpment

U-shaped valley

drumlins

outwash plain

• Some Glacial Features include:• U-shaped valleys

• Moraines: unsorted sediments

• Drumlins: elongated moraines

• kettle lakes: round glacial lake

• finger lakes: elongated glacial lake

• outwash plains: deposited by melt-water streams

• Erratic: large rock

deposited by a glacier

• Escarpment: steep cliff

• Horn: sharp peakDrumlins

outwash plain

Kettle lakes

River erosion: notice the V-shaped valleys and meanders (bending)

Valley glacier eroding a U-shape

Glacial features left behind

Glaciers / Rivers

A B

C

A B

C

Match the cross sectionsbelow with the lines onthe stream

A B C