- Created by: Bally
- Created on: 05-05-10 16:28
Types of rocks
there are 3 types of rocks: metamorphic rocks, sedimentery rocks and igneous rocks.
Metamorphic rocks are rocks that have "morphed" into another kind of rock. These rocks were once igneous or sedimentary rocks. The rocks are under tons and tons of pressure, which means heat builds up, and this causes them to change. If you look at metamorphic rock samples closely, you'll discover how flattened some of the grains in the rock are.
For thousands, even millions of years, little pieces of our earth have been eroded and worn away by wind and water. These little bits of our earth are washed downstream where they settle to the bottom of the rivers, lakes, and oceans. Layer after layer of eroded earth is deposited on top of each. These layers are pressed down more and more through time, until the bottom layers slowly turn into rock.
Igneous rocks are called fire rocks and are formed either underground or above ground. Underground, they are formed when the melted rock, called magma, deep within the earth becomes trapped in small pockets. As these pockets of magma cool slowly underground, the magma becomes igneous rocks. these are intrusive igneous rocks. these then form large crystals.
Igneous rocks are also formed when volcanoes erupt, causing the magma to rise above the earth's surface. When magma appears above the earth, it is called lava. Igneous rocks are formed as the lava cools above ground. these are extrusive igneous rocks. these then form small crystals