Ed Golson Outdoor Education

Types of rocks

Rocks may seem like they are all the same, but there are different types of rocks. Each is a little different and can make a big difference in the environment. The types of plants, animals, and soil in an area partially depends on what types of rocks and minerals are in the ground. What types of rocks do you expect to find at the Ed Golson Nature Park?

Igneous:  These are the rocks that form from solidified magma.  Deep down in the Earth temperatures and pressures are very high.  When the molten rock comes to the surface or is erupted by a volcano the cooled rocks become igneous rocks.  If the magma cools slowly, crystals and coarse rocks form from the magma.  If the magma is cooled rapidly on the other hand, the crystals are much smaller and the rocks are less coarse.  Examples of the rocks formed from the cooled magma are: Obsidian (which is volcanic glass), granite, basalt, and andesite. 

Sedimentary:  These types of rocks are formed at the Earth's surface.  They can be formed in water or in land.  Typically these layered rocks, are composed of materials from minerals, animals, or plants.  Temperatures and pressures are low at the Earth's surface.  The layers that make up these rocks are loosely cemented together.  These layers appear parallel to Earth's surface as well.  Common examples of sedimentary rock are: shale, conglomerate, sand, and gravel.

Metamorphic:  These types of rocks are formed deep under the Earth's surface.  They do not melt like igneous rocks.  Instead they become denser under the extreme heat and pressure found inside the Earth.  New minerals can be created by this process.  A few of these rocks are:  marble, gneiss (pronounced "nice"), and schist. 

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