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.
Students know natural
processes, including freezing and thawing
and the growth of roots, cause rocks to
break down into smaller pieces.
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,
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
Which type of rock would weather
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
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.