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