Igneouse, Metamorphic, Sedimentary Rocks

Topics: Sedimentary rock, Igneous rock, Rock Pages: 2 (355 words) Published: November 12, 2012
Three Types of Rocks:

There are three types of rocks and these three types of rocks are igneous, metamorphic, and sedimentary. These rocks all form differently. These rocks all can be made into another type of rock but they all are different and have probably been many different types of rocks.

Igneous rocks form from cooling lava or magma. Igneous rocks that cool from lava have a much shorter cooling time than rocks that cool from magma, this is because magma is underneath the earths surface and lava is above the surface. Lava is exposed to much cooler temperatures than it had in the middle of the volcano so it cools much quicker. Since igneous rocks made from lava cool much quicker they have a smaller crystal size. An igneous rock that formed from magma has time for the crystals to grow because the temperature difference is much less significant than if it had been formed from lava.

Metamorphic rocks form from heat and pressure being exerted onto a rock weather it is an igneous rock, a sedimentary rock or a metamorphic rock. The heat and pressure can leave bands on the rock. These bands are called foliation. If a rock is foliated that means that the rock has an appearance of bands but if the rock is non-foliated this means that it does not have an appearance of bands.

Sedimentary rocks form from WEDCC (weathering, erosion, deposition, compaction, and cementation). Three types of sedimentary rocks are clastic, organic, and chemical. Clastic rocks are rocks that have been formed from sediment or other rocks and have formed from WEDCC. Organic sedimentary rocks are rocks that are formed with plant and animal remains but also form from WEDCC. Clastic and organic sedimentary rocks can have fossils in them. Chemical sedimentary rocks form when water evaporated leaving the rock behind, this type of sedimentary rock however does not form from WEDCC.

All three types of rocks are very different. They form in very different ways. Have different...
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