Facts About Rock Formations

The beautiful rock formations of Bryce Canyon in Utah are formed from sedimentary rock.

There are three main types of rocks on the planet: sedimentary, igneous and metamorphic. All visible rock formations are made up of one of these three types of rock. Surface outcrop rocks can be spectacular to view; the Grand Canyon in Arizona is one example.

Rock Formations from Sedimentary Rocks

The sedimentary rocks sandstone, limestone and shale form the breathtaking Grand Canyon rock formation.

Sedimentary rocks are formed from deposits of sand, limestone, fossils and organic matter, or other sediment. One outstanding example of sedimentary rock formation is the Grand Canyon, which is made up largely of sandstone, limestone and shale. Gradual but steady erosion over millennia causes rocks to turn into rock formations.

Igneous Rock Formations

The Devil's Tower is an igneous rock formation, formed from an ancient volcano.

Igneous rock is created when lava that once flowed from volcanoes dries and hardens. One prominent example of an igneous rock formation is the Devil's Tower National Monument, which rises 1,267 feet above the Belle Fourche River in Wyoming. The structure itself is the result of ancient volcanic activity.

Metamorphic Rock Formations

Marble quarries in the Alps of Italy; Marble is a metamorphic rock.

Metamorphic rocks are created by natural forces from sedimentary or igneous rocks. Pressure and heat combine to change, or metamorphose, the rock from one type to another. Marble is an example of a rock that is formed from limestone to become a more valuable and refined type of rock.

References

• John Hopkins University for Technology in Education: How are Rocks Formed?
• Department of the Interior - National Park Service: Devil's Tower National Monument
• Tulane University: Types of Metamorphism
• BBC: Learning Zone Class: Metamorphic rock formation