Rapid
changes to the earth's surface can occur during an earthquake,
volcano or flood.
Directions:Read the following paragraphs and choose the correct main idea
for each paragraph.
1.There are
several events that can change the Earth's surface very quickly.
Volcanoes can erupt and spread lava, rock and ash for several miles.
Earthquakes can leave large cracks in the Earth's surface.
What
is the main idea?
2.
Most of the
world's volcanoes are part of the "The Ring of Fire." This is a ring
of volcanoes that form a circle around the Pacific Ocean. Thousands
of volcanoes make up "The Ring of Fire." These volcanoes formed the
sea floor and many underwater mountains.
What
is the main idea?
3.
Earthquakes are caused when the plates of the Earth's crust move.
Earthquakes happen along "fault lines" in the earth’s crust. When
the plates in the Earth suddenly shift, the Earth will begin to
shift, shake or tremble.
What
is the main idea?
4.Scientists
can measure the intensity of an earthquake. They use an instrument
called the Richter scale. The Richter scale compares the strength of
different earthquakes. Earthquakes below 2.0 usually can’t be
felt. Earthquakes over 5.0 on the scale can cause damage. A
magnitude 7.0 is a major earthquake and can cause tremendous damage.
What
is the main idea?
5.
Floods can cause tremendous damage.
They can ruin houses, roads and buildings. Floods can take down
trees and cause mudslides. It often leaves mud, sand and debris
behind. It can take months to clean up after a flood.
What
is the main idea?
6.
The earth's surface is
constantly changing. All over the world everyday there are
earthquakes, floods and volcanoes that quickly change our world.
Some changes are too small to see. Others cause tremendous
damage and costs millions of dollars to clean up.
