Igneous Rocks
By Brandi Waters
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Caption: granite, an igneous rock
All rocks can be put into one of three groups. The
groups are based on how the rock was formed. Some
rocks are formed slowly near the surface of the Earth.
Other rocks are formed deep underground by extreme
heat and pressure. One kind of rock is formed when
particles of rock, minerals, or crystals get so hot that
they melt. The rock that is formed when this melted
rock cools is called igneous rock. The Earth's core is
very hot. It is so hot that it can melt rock. Melted rock under the ground is called
magma. There are pools of magma deep under the surface of the Earth. Magma
always rises up. It moves towards the Earth's surface. Sometimes it cools before it
reaches the surface. It forms igneous rock. The rock stays underground. Sometimes
magma will erupt onto the Earth's surface through a volcano, then it is called lava.
Lava cools very quickly when it reaches the Earth's surface. Igneous rock is
formed.
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Igneous Rocks
1. Which of these is not one of the
2. Igneous rock is formed ______.
three groups of rocks?
Rock that is formed slowly near
the surface of the Earth
Rock that is formed quickly
when salts, crystals, and water mix
Rock that is formed when
melted rock, minerals, and crystals
cool
Rock that is formed deep
underground by extreme heat and
pressure
3. Melted rock under the ground is
called ______.
Lava
4. Melted rock is formed deep
underground and always ______.
Erupts through a volcano
Granite
Magma
A volcano
5. Magma forms ______ when it cools.
Cools before it reaches the
Earth's surface
Rises up toward the Earth's
surface
Forms crystals
Igneous Rocks
Explain how rocks deep underground end up as magma erupting from a
volcano.