Igneous rocks originate from magma, or liquid rock, from within the earth. Tremendous heat within the Earth's crust produces the liquid magma. When the magma cools and hardens either underneath or on the Earth's surface, it produces igneous rocks. The rate at which a rock cools from a liquid state to a solid influences its shape and texture, characteristics that help to classify the rock as igneous. In the Salt Lake Valley we find granite in the Big and Little Cottonwood Canyons.
Granite is an igneous rock that cools below the earth's surface.
Other igneous rocks cool above the surface of the earth and are known as volcanic rocks. Two examples of this, obsidian and pumice look very different from each other. Te most rapid cooling of lava results in obsidian. Metamorphic implies a change of form or composition. Metamorphic rocks are formed deep within the earth when previously existing rocks undergo changes due to intense pressure, chemical reactions and heat.