Rocks
Transcript of Rocks
Rocks are everywhere.
The crust of the earth is made of rock.
When magma cools, it forms intrusive igneous rock
Intrusive igneous rock cools slowly and usually has large grains. .
gabbrogranite
When lava cools, extrusive
igneous rock is formed.
Extrusive igneous rock cools quickly and usually has small grains.
basalt pumice
Some extrusive igneous rocks cool so fast, they
have no grains at all!
obsidian (volcanic glass)
Rivers can carry sediment that piles up under water.
The layers pile up and eventually become hardened into rock
Sedimentary rocks often look like glued together rocks, pebbles, or sand.
sandstone conglomerate
Some sedimentary rock forms when water evaporates and minerals are left behind.
Halite (salt) and gypsum are formed
this way.
Fossils are often found in sedimentary rocks.
Plants & animals are caught in the layers of sediment and leave an imprint in the rock.
Fossils tell us a lot about things that lived long ago.
Metamorphic rock is rock that has been changed by heat
and pressure.
.
Heat & pressure can change sandstone into
quartzite.
Granite can become gneiss,
…and shale can become schist!
But rocks don’t always stay the same. Any kind of rock can change into
another kind of rock.
Any rock that weathers into sediment can be pressed and cemented. It becomes sedimentary rock.
Any rock that is melted, Any rock that is melted, can cool off and can cool off and
become igneousbecome igneous rock. rock.
With enough pressure and lots of heat, any rock can
change and become metamorphic rock.
This pattern of This pattern of changing rock is changing rock is
called the…called the…
This changing is called the rock cycle
REVIEWREVIEW
1. Rocks are made of minerals.1. Rocks are made of minerals.
2. There are 3 kinds of rocks.2. There are 3 kinds of rocks.
3. Rocks made from cooled lava 3. Rocks made from cooled lava or magma are igneous.or magma are igneous.
4. Sedimentary rocks are made of 4. Sedimentary rocks are made of layers of sediments that have layers of sediments that have been cemented together.been cemented together.
5. Metamorphic rocks have been 5. Metamorphic rocks have been changed with heat and changed with heat and pressure.pressure.
6. All rocks can change in the 6. All rocks can change in the rock cycle.rock cycle.