Transcript Agents of erosion

AGENTS OF EROSION
APRIL 6, 2015
REVIEW OF EROSION
• Erosion is the process of
weathered rocks and soil
moving from one place
to another
• Erosion moves sedimentstiny pieces of broken
rock or soil
• After erosion, deposition
occurs when the pieces
of sediments and soil
settle on land or in water.
AGENTS OF EROSION
There are 5 agents (or causes) of erosion:
1. Gravity
2. Moving Water
3. Glaciers
4. Waves
5. Wind
(1) GRAVITY
• Definition: the force that pulls all things towards the
earth’s center
• Erosion begins with gravity pulling material towards
the center of the earth
• Mass Erosion is the downhill movement of
weathered materials caused by gravity
WHAT DOES GRAVITY CREATE?
• Mass movement, caused by
gravity, can create:
1. Mudflows- water, rock, and
soil mixed together that
moves downhill
2. Landslides- when rock and
soil slide quickly down a steep
slope
3. Slumps- a mass of rock and
soil suddenly slips down a
slope in one large piece
4. Creep- slow downhill
movement of rock and soil
(2) MOVING WATER
• Why it matters: Moving water has shaped more of
the earth’s surface than any other agent
• Moving water creates runoff- water from rain or
snow that flows into streams and rivers
• More runoff means more erosion!
• Moving water can form the following:
1. Streams
2. Valleys
3. Waterfalls
4. Deltas…. And more!
WATER EROSION
• Through erosion, a river can create
valleys, waterfalls, flood plains,
meanders, and oxbow lakes.
1. Waterfalls- formed when a river
meets hard rock that erodes slowly
2. Flood Plain- flat, wide area of land
along a river formed from water
over gently sloping land
WATER EROSION
3. Meanders- a loop-like bend in a
river that is formed from water
flowing through soft rock
3. Oxbow Lakes- a meander that has
been cut off from the river due to
sediments from a flood
WATER DEPOSITION
• Every time water moves, it carries sediments with it
that are dropped off in new places
• Through deposition, moving water can create
landforms, such as deltas and alluvial fans
1. Deltas- a triangular deposit of sediment located at
the mouth (end) of a river that empties into a still
body of water (like an ocean or lake)
2. Alluvial Fan- a wide, sloping deposit of sediment
formed where a stream leaves a mountain range
VIDEOS
Summary of water erosion
http://science.howstuffworks.com/environmental/318
83-howstuffworks-show-episode-4-power-of-watererosion-video.htm
What is the role of plate tectonics in water erosion?
https://www.youtube.com/watch?v=f62_MjB6-Ok
GROUNDWATER EROSION
• Sometimes rain or snow melts
and is soaked into the ground,
filling in cracks in rocks, creating
groundwater
• Groundwater can cause
erosion through chemical
weathering.
• Water combines with carbon
dioxide to create carbonic
acid. Carbonic acid can wear
down certain rocks and create
caves.
ACTIVITY
• You will randomly choose a feature of gravity or
water erosion.
• Using your workbook, create a poster that includes:
1. A detailed description of your type of erosion
2. How erosion or deposition creates this
3. A picture
This is due at the end of class. It will be graded as
classwork.
If you need me, raise a silent hand.
AGENTS OF EROSION
PART 2!
APRIL 20, 2015
AGENTS OF EROSION
There are 5 agents (or causes) of erosion:
1. Gravity
2. Moving Water
3. Glaciers
4. Waves
5. Wind
We are going to focus
on the last 3 today!
(3) GLACIAL EROSION
• Definition: a glacier is a large
mass of ice that move slowly over
land
• 2 types of glaciers
1. Continental: glacier that covers
most of a continent or large
island and they flow in all
directions
2. Valley: a long, narrow glacier
that forms when snow and ice
build up high in a mountain
valley
ICE AGE
• An ice age is when a continental glacier covers a
large part of the earth’s surface
• About 1 million years ago, 1/3 of earth’s land was
covered in glaciers!
What is the ice age?
https://www.youtube.com/watch?v=dJ5GYQrkvxI
Movie Preview:
1. What types of erosion do you see?
2. What about this preview is realistic? Unrealistic?
https://www.youtube.com/watch?v=cMfeWyVBidk
HOW GLACIERS CAUSE EROSION
2 processes by which glaciers erode the land
1. Plucking: when rocks are broken by moving glaciers
and then freeze to the bottom of the glacier. As the
glacier moves, the frozen rocks stuck to the bottom
move, too.
2. Abrasion: when these frozen rocks stay on the glacier
and are dragged across the land. This dragging of
rock can scratch the rock.
HOW GLACIERS CAUSE DEPOSITION
Once a glacier melts, it deposits the sediment it
eroded from the land, creating various landforms.
These sediments deposited by a glacier are called till
Glaciers can create the following landforms:
• Moraine- when a glacier deposits a mountain or
ridge
• Kettle- a small depression or ice is left in a glacial till
• Fiord- a valley that was created by a glacier that is
now filled with water
• Cirque- a bowl-shaped hollow eroded by a glacier
(4) WAVE EROSION
How do waves cause erosion and deposition?
• Energy in waves come from the wind
• When the wind hits the water, waves form
• As the wave hits the shore, it moves the sand
forward, then backwards into the water.
• The waves also shape the shoreline
https://www.youtube.com/watch?v=775FQ5_YLvE
WAVE EROSION
Waves shape the coast through
erosion by breaking down rock
and moving sand and other
sediment
Waves change direction based
on the land masses that they hit
A headland is a part of the shore
that sticks out into the ocean
WHAT WAVES CAN CREATE
Wave erosion can create…
• Sea Cave
• Wave-Cut Cliff
• Sea Arch
Wave deposition can create…
• Beaches
• Sandbars
• Barrier Beaches
• Splits
(5) WIND EROSION
Wind causes erosion by deflation.
• Deflation: the process by which wind
removes surface materials, like
sediments and sand, to new place
Wind deposition occurs once the
sediments picked up by wind fall to the
ground. This can create…
• Sand dunes- wind blown sediments
that has built up
• Loess deposits- pieces of sediment
smaller than sand that are carried by
the wind
CLASSWORK
1. Silently and independently complete your study
guide (front and back)
1. Use your notes and workbook ch. 3 to help you.
2. Use your foldable to help you
2. Finish your lab #28 if you have not already
finished.
3. When you are done, complete pages 95-97 in
your workbook
1. SKIP: #10, 13, 17, 21
4. Raise a silent hand when done with 1-3
If you need me, raise a silent hand.