4th Grade-Ch. 9 Lesson 3 How Can Earths Surface Change Rapidly
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Transcript of 4th Grade-Ch. 9 Lesson 3 How Can Earths Surface Change Rapidly
Ch. 9Lesson 3
How can Earth’s surface change
rapidly?
• forms @ weak spot in Earth’s crust where magma is forced up & reaches surface
• causes rapid changes
volcano
ashcrater
Mount St Helens
Before After
will not erupt again
extinct
has frequent eruptions or shows signs of future eruptions
active
Has not erupted for a long time (sleeping)
dormant
4 layers of Earth
outer layer
of rock
plates•large pieces that Earth’s crust is divided into
•constantly moving
fault•break in Earth’s crust
earthquake•sudden movement that causes Earth’s crust to shake
•San Andreas fault in Calif.- many earthquakes
San Francisco earthquake of 1906
focus= place underground where plates start to move- where earthquake begins
epicenter= place on Earth’s surface above focus
huge ocean wave created by an earthquake or volcano