Transcript Shaping the Land - Colts Neck Township Schools

Earth’s Changing Surface

Erosion – the process of moving
weathered rock and soil from one place
to another.

Sediment – the material MOVED by
erosion.

Deposition – the dropping (depositing) of
sediments as energy of motion
decreases.

What is a CYCLE?
› A process that repeats itself.
3 processes are constantly working on earth.
 As one area on earth is WEATHERED (broken
down), ERODED (carried away), sediments are
DEPOSITED in another area (built up!)
 Constantly changing the shape of the Earth.


Agents (the thing) that erodes the surface of
the earth:
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
Gravity
Running Water
Wind
Ice
Waves
Which “agent” is the most effective at erosion?
› RUNNING WATER – is the major agent shaping the
surface of the Earth. Found everywhere.

Gravity – the force that moves rock and
other materials DOWNHILL

Causes MASS MOVEMENTS – processes
that move sediments downhill. Some
types are fast, others are slow.

4 types
› Rockslides/Landslides
› Mudslides
› Slump
› Creep

Most destructive
› Rock and soil slide
QUICKLY down a slope

Common in
mountainous areas,
usually occur after
heavy rains or
earthquakes.

Forms TALUS SLOPES at
bottom (pile of rocks)
Notice the scale – the size of the men to the size of the rocks
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Water with
sediments, gravity
causes the mixture to
slide downhill.
Occurs in DRY AREAS
AFTER heavy rains.
Enough energy and
mass to destroy
things in path
(houses, etc.)
Deposits at bottom of
hill are usually coneshaped.

Rock and soil suddenly
slips down a slope.
Does not travel far.

Moves in ONE LARGE
MASS! (different than
landslide/rockslide)

Looks as if someone
pulled the bottom out!

Sediments slowly move
downhill

Often caused by freezethaw action.

Happens over several
years.

Evidence of creep by
leaning utility poles,
fences, tree trunks.

The most influential force in erosion is
water.

Water’s ability to move materials from
one location to another, along with the
fact that it is found everywhere along
the surface of the earth, makes it a
superb tool for erosion.

Water erosion begins with a
splash of rain

As water from rain moves
over land it carries pieces
of sediment with it – this
water is called RUNOFF!

Water ALWAYS flows from
higher to lower elevations,
i.e., it flows downhill!

Rivers create:
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Valleys and Canyons
Waterfalls
Floodplains
Meanders
Oxbow Lakes
Rivers often START on steep mountain
slopes, pick up sediments from mass
movements or from runoff.

Valleys (V-Shaped Valleys)
› Near the source of a river, fast-flowing and
has a narrow
straight course.
› Sediments along the side get carried away
quickly
› Creates a deep, V-shaped valley

CANYONS
› A narrow, deep, rocky, and steep-walled
valley carved by a swift-moving river.
› Its depth may be considerably greater than
its width.
The Colorado River has eroded away the layers of sedimentary rock and formed
the Grand Canyon.

http://www.youtube.com/watch?v=ktf7
3HNZZGY&feature=related
Grand Canyon Flyover
 http://www.youtube.com/watch?v=h3jY
4wzQPGs&feature=bf_prev&list=PL280EE
176A94E121D&lf=results_video

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Waterfalls
› When water meets hard rock that is not
easily worn away, it continues to flow
downstream to softer rock and wears the
soft rock away!
DRAW THIS!
The “falls” are located near the center of town in Tinton Falls, near the mills and
MJ’s pizza.

Flood plain
› Flat land next to a river or a stream
› As rivers flow along less steep land, they
spread out
› During a flood, this is where all of the excess
water goes!
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Meander
› A loop—like bend in the course of a river
› Sediments get pick up and dropped off
› The older a river is, the more
erosion has occurred and the
more and more curved it
becomes
Glen Canyon is in Utah and Arizona

Oxbow Lake
› A meander that has been cut off from the
river because of sediments
Draw this!
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Moving water carries sediments and when
the water slows down the sediments drop
out and get “deposited”
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Deposition BUILDS up new landforms

3 types:
› Alluvial fans
› Deltas
› Flood plains
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When a fast moving stream slows down
(i.e., when it comes out of a mountain
range)
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Deposits sediments in the shape of a
wide fan
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The end of a river; when it flows into an
ocean or a lake
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The water is no longer moving downhill,
slows down and sediment fall to the
bottom.
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The landform that is built up from these
deposits is a DELTA
A and C are islands formed by the river
B is the Mississippi River deposits and D is the Mississippi Sound

Heavy rains or melting snow can cause
rivers to rise over the edges of its bank
and spread out over its “flood plain”
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As the water recedes, sediments drop
out

Makes fertile soil; good for crops.

Any large mass of ice that moves over land.
› Valley glaciers – long, narrow snow and ice that
build up in valleys of mountains
› Continental glacier – a glacier that covers much
of a continent or large island. Larger than valley
glaciers

Form when snow build up year after year,
pressure of the snow compresses the snow
at the bottom into ice, and eventually
gravity begin to pull it down the mountain.
Near Banff, Canada
Couloir and Hanging Valleys
MINI LAB
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How do glaciers change the land?
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Hold the ice with paper towels. Rub the ice,
sand side down, over a bar of soap.
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What happens to the surface of the soap?
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Record your observations, wipe up your desks.
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Return the soap to the paper plates.
Move slowly (centimeters to meters daily)
 Creates U-shaped valleys!
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Valleys carved by glaciers – notice the U shape rather than an V shape!
U-shaped valleys found in Alaska
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Major force of erosion
› Plucking
 Picking up of rocks since they froze to the bottom
of the glaciers
› Abrasion
 Dragging the rocks frozen to the bottom of the
glacier causes:
 Striations – gauging and scratching of the
bedrock
Striations in Canada
Rock in Central Park, New York

As a glacier retreats (or melts), it drops the
sediments that it “plucked” up along the
way – called “till”

Till – the mixture of sediments that a glacier
drops on the surface

Moraine – the till deposited by the edges of
a glacier
› Terminal moraine – the till left behind at the
furthest location the glacier traveled.
› Long Island, New York is a terminal moraine.
Terminal Moraine, Lateral Moraines and Till
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Kettle Lakes
› Glaciers drop chunks of ice in the till
› Ice melts, fills the area with water – called a
kettle – if the water stays it forms a lake
› Northwest NJ, Stokes State Park – hundreds
of Kettle lakes and ponds
› The Great Lakes are kettle lakes
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Erratic
› Rocks dropped by glaciers – very different in
shape and type from “native” rocks
› Some are quite large!
Tripod Rock on Pyramid Mountain
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Wind, by itself is the weakest agent of
erosion
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In areas where few plants survive to hold
soil in place (i.e., deserts, beaches) wind
is powerful.
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The main way that wind causes erosion is
by DEFLATION and ABRASION!
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Deflation – the process by which wind
removes surface materials. Lifts dirt, blows
it around, and drops it off somewhere
else.
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The stronger the wind, the larger the
particle it can pick up and move.
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All particles picked up by wind will
eventually fall back down – may form
DUNES.
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Created on beaches and in deserts – when
sand is dropped by wind – usually when the
wind hits an obstacle.
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Can be long and parallel, can be Ushaped, can be small or large and move
over time.
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Sand dunes constantly shift location with
the wind, plants help to keep the dunes in
place.
Formed in a U Shapes from the wind due to little vegetation!
Also called TRANSVERSE sand dune! The wind blows perpendicular to the dune!
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Wearing away of rocks or beaches due
to wave action
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Creates:
› Sea Caves
› Sea Cliffs
› Sea Stacks
› Arches
› Coves
Beach erosion
Spits
Barrier Islands