CH 1 Changes to Earth’s Surface

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CH 1Changes to Earths Surface

• Science
• 4th Grade
• Bailey

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Lesson 1

• What processes change landforms?
• Three main surface process are weathering,
  erosion, and deposition
• The process of weathering breaks down rock into
  soil and sediment through wind, water, ice, and
  mass movement
• Erosion moves the sediment from one place to
  another
• Deposition deposits the sediment in a new location

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landform

• Physical features on the Earths surface such as
  canyons, rocks, cliffs, beaches, mountains

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weathering

• Process of breaking down rock into soil, sand,
  and other tiny pieces called sediment through
  wind, water, glaciers, volcanic eruptions,
  earthquakes.
• Weathering can be caused by water, wind, ice, or
  mass movement

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water

• Water rivers carve canyons, ocean waves weather
  cliffs, rain seeps into cracks in rocks, freezes
  then expands breaking the rocks

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wind

• Wind carries bits of sand and rock which
  sandblast rocks, move sediment from one place to
  another, and create sand dunes

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ice

• Ice can chance landforms through glaciers which
  are thick sheets of ice that move slowly.
  Glaciers erode sediment from one place and move
  it to another

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Mass movement

• Mass movement is the downhill movement of rock
  and soil because of gravity
• Mudslides are wet while landslides are dry
• Sinkholes are holes that open up suddenly due to
  rocks under the surface that have be dissolved

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erosion

• Process of moving sediment from one place to
  another

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deposition

• Process of dropping or depositing sediment in a
  new location

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Lesson 2 What are the process that change
Earths surface that begin inside the Earth?

• There are three main process beginning inside the
  Earth that change Earths surfaces mountains,
  volcanoes, and earthquakes

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Earths interior

• There are three distinct layers
• Outer layer is crust made of rock
• Mantle is under the crust and made of solid (top)
  and liquid (bottom) also called magma
• Core is center of Earth and is the hottest layer
  outer core is liquid iron while inner layer is
  solid iron

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Earths Crust Movements

• Earths surface is made up of tectonic plates
  which are rigid blocks of crust and upper mantle.
• There are 12 major plates
• California is on the North American plate and the
  Pacific plate

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Tectonic plates

• Plates float on the soft rock of the mantle
• Pressure and heat create currents which cause the
  plates to move very slowly
• Plates can pull together, push apart, or slide
  next to each other
• When plates collide-mountains form and volcanoes
  erupt while in the ocean trenches form
• When plates pull apart, valleys with volcanoes
  form while in the ocean ridges and volcanoes form
  and new sea floor forms
• When plates slide past each other earthquakes
  occur

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mountains

• Most mountains form from the collision of two
  continental plates such as the Cascade mountains
  and Himalayas

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volcanoes

• Most form at plate boundaries
• Volcanoes are mountains formed by lava and ash
• Ring of fire is at edge of Pacific Ocean at the
  plate boundaries between the continental and
  oceanic crusts meet
• Hawaii is a hot spot, where a hole in the crust
  allows magma to escape
• Magma is called lava once it erupts from a
  volcano
• There are no volcanoes on the East coast because
  there are no plate boundaries there

Hawaii
Cascade Range of volcanoes
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Three Types of Volcanoes

• Shield-broad volcanoes with gently slopes, mostly
  lava
• Cinder cone volcanoes-tall and narrow with steep
  slopes, mostly ash
• Composite volcanoes-wide with steep slopes made
  of 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 is released as plates crush together,
  scrape past each other, or bend along boundaries
• 1 million earthquakes occur each year, with 81
  occurring within the ring of fire
• Faults are places where pieces of crust move
• The largest fault in California is the San
  Andreas Fault
• The energy sent out by an earthquake is called
  seismic energy which is measured by a seismograph

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Continental Drift

• The movement of the plates has occurred for
  millions of years
• 200 million years ago most of the continents were
  in one supercontinent called Pangaea
• Looking at the continents one can see puzzle
  pieces that once were together
• Eventually, millions of years from now, Los
  Angeles will be where San Francisco is today and
  the edge of California will break off.

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Rock Record

• Fossils, remains or traces of past life, found in
  sedimentary rock show how life has changed
• The Grand Canyon is one mile deep and 2 billion
  years old
• The rocks at the top of the Grand Canyon are 250
  million years old
• Similar fossils have been found on several
  continents suggesting that at one time the
  continents were connected