Fremont Magnet Elementary

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Rapid Changes on the Earth


  1. Students know some changes in the earth are due to slow processes, such as erosion, and some changes are due to rapid processes, such as landslides, volcanic eruptions, and earthquakes.
  2. Students know natural processes, including freezing and thawing and the growth of roots, cause rocks to break down into smaller pieces.
  3. Students know moving water erodes landforms, reshaping the land by taking it away from some places and depositing it as pebbles, sand, silt, and mud in other places (weathering, transport, and deposition).

1. Slow Changes Review

Which of these would most affect the amount of sediment a river can carry?

  the color and shape of the sediments
  the temperature and amount of salt in the water
the size and speed of the river

Which type of rock would weather faster?

    oddly shaped rock
smooth rock
cracked rock




2. Fast changes in the Earth

You learned last week that new valleys, deltas, canyons and beaches are made over many years by the gradual changes caused by weathering and erosion.

Not all changes are slow, some are so fast they only take a few seconds.  Can you think of anything that quickly changes the Earth's surface?

How about landslides, volcanoes or earthquakes.  All of these things cause rapid changes to the Earth's landscape.



3. Where do mountains come from?


You know that the Earth is always changing. If weathering and erosion are always wearing away mountains, why isn't everything flat?  Where do mountains come from?

There are several ways to make mountains, two of the quickest ways to make mountains are earthquakes and volcanoes.

Click here to watch a brainpop movie about mountains.

4.  How do earthquakes and volcanoes make mountains?

 The Earth is divided into different sections called tectonic plates.
Major Tectonic Plates

These plates move about as fast as your fingernail grows.  As they move they cause earthquakes and volcanoes.  Click here to see an animation that shows tectonic plates on EarthClick here to discover where most earthquakes are located. What do you notice about the location of earthquakes and volcanoes?

Click here to watch a brainpop movie about plate tectonics

Look at this picture.  Can you see the line where two plates come together?


Click here to make a mountain.

The San Andreas fault is the border between two tectonic plates—the North American Plate and Pacific Plate. Los Angeles is located on the Pacific Plate, and San Francisco is on the North American Plate. In a few million years, the two geographic areas will be right next to each other because the western side of the fault (the Pacific Plate) is moving northward with respect to the rest of the state. The fault is moving at about 2 centimeters (just under an inch) per year.



5.  Old and new mountains

  Look at these different mountain ranges.  Which do you think is the youngest?  Why?



Click here to see an animation of the Himalaya Mountains being formed

How are rocks made?

Click here and follow the instructions



National Geographic Oct 2006

Ring of Fire

How are mountains made

Hot Spots island animation

Cutaway of plate

Fault pictures

plate diagram



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