Unit C, Chapter 1, Lesson 1 Changes to Earth

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Unit C, Chapter 1, Lesson 1Changes to Earths
Surface

• WB 117
• Lesson 1- Surface Processes that change landforms
• Weathering
• Erosion
• Deposition

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Vocabulary WordsC6

• Landforms
• Weathering
• Erosion
• Deposition
• Mass movement

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Changing Landforms

• Landforms-physical features on its surface
• Might seem like they never change,
• But they do!

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Landforms from Mrs. Carness Trip to Utah
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More landforms from Utah!
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Rock climbersHow many can you find?
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More landforms!
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Constantly changing!

• Forces such as flowing water, waves, wind, ice,
  and even movements inside the Earth are
  constantly changing landforms.

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Changes

• Sometimes changes happen fast enough for people
  to see.
• Example a volcano might erupt suddenly and blow
  away a mountaintop,
• or a powerful hurricane might sweep away a sandy
  beach.

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What are some of the forces that change landforms?

• Wind
• Moving water
• in the form of rivers and waves
• Glaciers
• Forces inside the Earth
• (such as volcanic eruptions)

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Water

• The shaping of landforms starts when weathering
  wears away rock.
• Weathering-the process of breaking rock into
  soil, sand, and other tiny pieces, or particles,
  called sediment.
• WATER is an important agent, or cause, of
  weathering.

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WeatheringVideo Clip
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Water weathers rocks in several ways.

1. Fast-flowing waters can carve deep canyons in
   rock.
2. Ocean waves can weather cliffs and cause them to
   fall into the sea.
3. When it rains, water seeps into tiny holes, or
   pores, cracks in rock. If the water freezes,
   it expands, breaking the rock.
4. Rain that is acidic can dissolve the rock.
5. Flowing water tumbles rocks into one another,
   breaking them into pieces and smoothing their
   edges.

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What is erosion?

• Erosion is the process of moving sediment from
  one place to another.

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Erosionvideo clip
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What is Deposition?
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Water

• Water is not only an important agent of
  weathering but also the chief agent of erosion.
• Water can erode great amount of sediment.
• Rainfall erodes sediment and carries it into
  rivers streams.
• Rivers pick up the sediment move it downstream.
  
• Flood plains can become rich agricultural areas.
• Areas of new land are called deltas.

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What is the difference between weathering
erosion?
Weathering breaks rock into sediment
Erosion moves sediment from one place to another.
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C8- Wind Ice

• Wind is another agent of weathering and erosion.
  
• Wind can carry bits of rock and sand that weather
  rock surfaces moves sediment from 1 place to
  another.
• If the wind blows hard, it can erode a lot of
  sediment.

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Wind erosion

• Wind erosion can blow sand into large mounds
  called dunes.
• Huge dunes as much as 325 ft high form in some
  deserts.

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Ice-Glaciers

• Ice in the form glaciers can also change
  landforms.
• Glaciers are thick sheets of ice, formed in areas
  where more snow falls during the winter than
  melts during the summer.
• Because of a glaciers great size and weight, it
  erodes everything under it.
• Glaciers erode sediment from one place and
  deposit it in another.

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Ice Berg
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2 kinds of Glaciers

• Valley Glaciers- are found in high mountain
  valleys.
• They flow slowly down mountainsides, eroding the
  mountain under them and forming U-shaped valleys.
  
• Only a few valley glaciers remain in North
  America, and they are melting rapidly!

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Valley Glacier

• A glacier in the Sierra Nevada. Glaciers are
  formed when snow accumulates faster than it
  melts. As the snowpack thickens, its weight
  compresses or squeezes it into ice. The ice can
  flow very slowly, as one mass, down a valley or
  canyon. Rocks caught in the glacier act like
  grinding stones, helping to carve a U-shaped
  valley. Yosemite is a classic example of this
  type of glacier action.

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Continental Glacier

• Continental glacier are ice sheets that cover
  large areas of Earth.
• They cover almost all of Greenland and Antarctica
  today.
• 1000s of years ago, when the climate was cooler,
  continental glaciers covered Europe, Canada, and
  the northern United States.

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Mass Movement

• Mass movement is the downhill movement of rock
  and soil because of gravity.
• A mudslide is one type of mass movement
• that moves wet soil.
• Landslide is another type that can change
  landforms quickly that move dry soil.
• Occur when gravity becomes stronger than the
  friction that holds soil in place on a hill. The
  soil falls suddenly to the bottom of the hill.

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Other Types of mass movements

• One type of mass movement that occurs slowly, is
  called creep.
• Creep occurs when soil moves slowly downhill
  because of gravity.
• Creep is so slow that changes in landforms are
  hard to observe directly.
• The land may move only a few centimeters each
  year.
• Overtime, creep can move fences, utility poles,
  roads, and railroad tracks.

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A sink hole

• A sink hole is a large hole in the ground that
  opens suddenly.
• Form after rock under the surface has dissolved
  or become weak.
• Often appear in areas of limestone rock, because
  limestone dissolves easily.
• Rain seeping into the ground combines with carbon
  dioxide from the air to form a weak acid called
  carbonic acid. This acid dissolves limestone,
  forming huge holes.

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Sink HoleVideo Clip
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New Landforms

• Erosion and deposition can change landforms or
  produce new ones.
• Rivers can deposit sediment that builds deltas.
• They can also change their path producing new
  lakes on wide flood plains.
• (Picture captions at the bottom of pg C10.)
• The river follows the shortest route, its flow
  cuts off the loop. The old loop forms a
  crescent-shaped body of water called an oxbow
  lake.

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Glaciers are major forces that help form new
landforms

• As the glaciers of the last Ice Age moved
  forward, they pushed mounds of rock and soil in
  front of them.
• When the glaciers melted, they left behind at
  their lower ends long ridges of soil rock,
  called terminal moraines.
• Long Island Cape Cod are examples of terminal
  moraines.

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New Islands forming

• New islands can be formed by volcanic eruptions.
• Underwater volcanoes increase their height by
  depositing melted rock and ash.
• In time, they break through the sea surface as
  islands. (Example Hawaiian Islands)
• Daily eruptions add size to an island.

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What new landforms are created by erosion
deposition?

• Deltas, oxbow lakes, terminal moraines, and
  volcanic islands

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Summary

• Weathering breaks down the rock of Earths
  surface into soil, sand, and other small
  particles.
• Agents of erosion (such as water, wind, and ice)
  change Earths landforms by moving rock soil.
• Water can carve canyons deposit sediment to
  form deltas.
• Wind can form sand dunes.
• Ice can carve U-shaped valleys and leave
  landforms like terminal moraines.
• Even volcanoes can produce new landforms.

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Lesson 1 Review Questions

• What is erosion?
• The process that picks up sediment moves it
  around.

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2- What is deposition?

• The process that leaves sediment in different
  places.

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What forces cause erosion deposition?

• Water, wind, glaciers, gravity, forces within the
  Earth (volcanoes)

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A type of mass movement is a ?

• A. Glacier
• B. Delta
• C. Mudslide
• D. Terminal moraine
• C. mudslide

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C14, Lesson 2Processes that Begin in Earths
Interior

• WB117
• Mountain building
• Volcanoes
• Earthquakes

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WHO AM I?CRUST

• I am Earths outer most layer
• I reach about 20 miles below the surface of the
  Earth
• it is made of rock mostly basalt and granite.
• Is rigid, Very thin compared to the other layers.
  
• This layer is broken into large pieces or plates
• The Earth is thinner under the oceans.
• We live on this layer

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Who am I?

• What is the layer of rock beneath Earths crust?
• Just under the crust,
• The rock is solid near the top (composed mostly
  of iron and magnesium)
• The rock that is deeper is soft because of
  intense heat
• No one has ever been here, but soft, hot rock
  from this layer sometimes reaches Earths surface
  through volcanoes.
• MANTLE

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Outer Core
Who am I?

• What is the inner most layer of Earth?
• This is the hottest layer
• It is a solid due to extreme pressure

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Who am I?
Who am I?

• What is made of liquid, or molten, iron-nickel
  layer that surrounds the inner core?

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Inner Core

• The Inner core is made of solid iron-nickel
• Even though the core is very hot, great pressure
  at the center of Earth keeps the inner core solid.

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The Earths Crust
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What parts of the Earth are solid rock?

• The crust
• The upper part of the mantle
• The inner core

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Earths Interior Video Clip
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Earths InteriorVideo Clip
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Earths Crust Moves

• Earths surface is not a single piece of rock.
• It is made up of many plates.
• Plates are rigid blocks of crust and upper mantle
  rock.
• Most of North America, Greenland, and the western
  half of the North Atlantic Ocean are on the North
  American plate.
• There are 12 major plates in all.
• Earths plates fit together like pieces of a
  jigsaw puzzle.

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Plates

• The plates are enormous, and they float on the
  soft rock of the mantle.
• Pressure heat within the Earth produce currents
  in the soft rock of the mantle.
• As the mantle moves, the plates floating on it
  move, too.
• Plates movement is very slow-only a few
  centimeters each year.

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Plate Movement

• Plates are right next to each other, the movement
  of 1 plate affects other plates.
• Some plates push together.
• Some pull apart.
• Other plates slide past each other.
• As plates move around, they cause changes in
  Earths landforms.

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Plates Colliding

• Where plates collide, energy is released new
  landforms are produced.
• On land, mountains rise up and volcanoes erupt.
• On Ocean floor, deep trenches form.

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Plates Pulling apart!

• As plates pull apart on land, valleys dotted with
  volcanoes develop.
• The rift, or crack, will one day result in a
  complete separation from the rest of the
  continent.
• Where plates pull apart under the sea, ridges
  volcanoes form.
• This spreading forms new sea floor at the ridges.

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Scraping and sliding past each other

• When plates scrape and slide past each other,
  they shake Earths surface.
• The plates rub and shake as they grind past each
  other, causing earthquakes.

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What are Earths plates?

• Rigid blocks made up of crust and upper mantle
  rock.

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Mountain Foundations

• Mountains are Earths highest landforms.
• They form as the crust folds, cracks, and bends
  upward because of the movement of the Earths
  plates.
• Most of the highest mountains form where
  continental plates collide. As the plates push
  together, their edges crumple fold into
  mountains.
• (Example Himalayas, highest mountain range,
  formed this way.)

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Mountain Foundations

• At some places, continental oceanic plates
  collide.
• Because continental rock is lighter than seafloor
  rock, the continental plate moves up over the
  oceanic plate.
• (Example The Cascade Mountains, near the
  Pacific Ocean, formed this way.)

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Mountain Foundations

• Mountains do not form only at the edges, or
  boundaries, of plates.
• Some form where pressure from movement at the
  boundaries pushes a block of rock upward.
• (Example The Grand Tetons of Wyoming rise
  straight up from the flat land around them.)

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Mid-ocean Ridges

• Plates that pull apart leave gaps between them.
• Magma bubbles up between the plates.
• Magma is hot, soft rock from Earths mantle.
• Magma builds up along the cracks, forming long
  chains of mountains under the ocean.
• These mountains are called mid-ocean ridges.
• The Mid-Atlantic Ridge is Earths largest
  mountain range.

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How do most of the highest mountains form?

• From the collision of two continental plates.

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Volcanoes

• A volcano is a mountain formed by lava and ash.
• Lava is magma that reaches Earths surface.
• Ash is small pieces of hardened lava.

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Volcanoes

• Chains of volcanoes form where a continental
  plate and an oceanic plate collide.
• The edge of the oceanic plate pushes under the
  edge of the continental plate.
• The leading edge of the oceanic plate melts as it
  sinks deep into the mantle.
• The melted rock becomes magma that forces its way
  up between the plates.
• The volcanoes of the Cascades, such as Mt. St.
  Helens, formed this way.

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Volcanoes

• Sometimes volcanoes form in the middle of plates,
  over unusually hot columns of magma.
• The magma melts a hole in the plate rises
  through the hole, causing a volcanic eruption.
• Example The Hawaiian Islands are the tops of a
  chain of volcanoes that formed in the middle of
  the Pacific plate.

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Volcanoes

• Volcanoes take on their characteristic shapes as
  lava ash build up around their openings, or
  vents.

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Volcanoes

• Shield volcanoes are broad volcanoes with gentle
  slopes. They are mostly lava.
• Cinder cone volcanoes are tall and narrow, with
  steep slopes. They are mostly of ash.
• Composite volcanoes are wide and have fairly
  steep slopes. They are lava and ash.

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Volcanoes

• Many volcanoes are located at plate boundaries
  around the Pacific plate. Thats why this area
  is called the
• Ring of Fire.

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What is a volcano?

• A mountain formed by lava and ash.

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Earthquakes

• An earthquake is a shaking of the ground caused
  by the sudden release of energy in Earths crust.
• The energy released as plates crush together,
  scrape past each other, or bend along jagged
  boundaries can cause great damage.
• On March 27, 1964, thousands of people in
  Anchorage, Alaska, were in a possibly the most
  powerful earthquake ever recorded.
• It knocked down houses, broke up roads, cut
  water, gas, and power lines all over the area.

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Earthquakes

• Earthquakes are very common.
• More than 100 of them occur each year.
• However, most are too small to be felt or to
  cause damage.

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Earthquakes

• Faults, or places where pieces of crust move
  caused by breaks in the middle of a plate as
  forces press in on the plate.

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Earthquakes

• An earthquake sends out energy in the form of
  seismic waves.
• Seismic waves are like ripples that form on a
  pond when a stone is tossed in.
• Scientists measure and record seismic waves on an
  instrument called a seismograph.
• These measurements can be used to measure
  compare the strengths of earthquakes.

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Earthquakes

• The Richter scale is used to measure relative
  strengths, or magnitudes, of earthquakes.
• On this scale an earthquake with a magnitude of
  7.5 is more powerful than an earthquake with a
  magnitude of 6.5.

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Earthquakes

• What is an earthquake?
• The shaking of the ground caused by the sudden
  release of energy in Earths crust.

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Video ClipPlates, Volcanoes, Earthquakes
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Plates, Earthquake science
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Video Clip 20 min.Plate Movement Earthquake
Science
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Lesson 2 Summary

• Earth has 3 layers
• Crust,
• mantle,
• core
• Rock of the crust upper mantle makes up plates
  that fit together like puzzle pieces.
• Earths plates collide, pull apart, and slide
  past each other.
• Most mountains volcanoes form plate boundaries.
  
• Many earthquakes occur at plate boundaries.

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Review ?s

• Describe three ways in which Earths plates
  interact.
• They push together,
• pull apart, and
• slide past each other.

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2

• What is magma where does it come from?
• Magma is hot, soft rock that comes from the lower
  mantle.

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3

• How do volcanoes form where oceanic
  continental plates collide?
• The leading edge of the oceanic plate is pushed
  deep into the mantle where the rock melts and
  magma rises to the surface between the plates.

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4

• Many strong earthquakes are caused by
  ___________.
• A. plates sliding past each other
• B. lava flowing down the side of a volcano
• C. plates spreading apart
• D. hot magma
• A. plates sliding past each other

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Lesson 3,WB 117

• Pangea
• Gondwana-Laurasia
• Present Earth

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Lesson 3How Earths Surface Has Changed

• Continental Drift-is the theory of how Earths
  continents move over its surface.
• The surface is constantly changing because of
  continental drift.

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Pangea

• Pangea- about 225 million years ago, all of the
  land on Earth was joined together in one
  supercontinent

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Pangea Info from a website

• ALFRED WEGENER AND PANGAEA In 1915, the German
  geologist and meteorologist Alfred Wegener
  (1880-1930) first proposed the theory of
  continental drift, which states that parts of the
  Earth's crust slowly drift atop a liquid core.
  The fossil record supports and gives credence to
  the theories of continental drift and plate
  tectonics. Wegener hypothesized that there
  was an original, gigantic supercontinent 200
  million years ago, which he named Pangaea,
  meaning "All-earth". Pangaea was a supercontinent
  consisting of all of Earth's land masses. It
  existed from the Permian through Jurassic
  periods. It began breaking up during the late
  Triassic period.

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The Rock Record

• Sedimentary rock- is rock formed from sediments
  that have cemented together.
• Fossils- are the remains or traces of past life
  found in sedimentary rock.
• Scientists study fossils to find out how life on
  Earth has changed.

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Youngest and Oldest rocks

• The youngest rocks are found on top of the canyon
  walls. (Grand Canyon in Arizona)
• The oldest rocks are found at the bottom of the
  canyon walls.