Rocks Rock! Part 2     Back to Geology Online 1     You are familiar with the metamorphosis of butterflies, the cycle that begins with an egg and goes through caterpillar to chrysalis to butterfly. You know that butterflies are metamorphic, but did you know that rocks are metamorphic as well? It's true!   2     We covered igneous and sedimentary rocks in Part 1. They are related to the third type of rock. When certain processes are applied to igneous or sedimentary rocks, they become metamorphic rocks, the third type of rock found on Earth.   3     Metamorphism occurs within the Earth's crust rather than on the surface. Most metamorphism takes place from 6 to 19 miles below the Earth's surface. That means we don't see metamorphic rock nearly as often as the igneous (from lava or magma) or sedimentary (layers of pressed sediment) types of rocks.   4     There are three main causes of metamorphism. The first is heat, which breaks down the chemical bonds in a rock's minerals, causing them to form new minerals. This results in a new rock. The type of rock that is formed depends on the type of rock it was originally.   5     The second cause is pressure. The deeper inside the crust rock material is, the more it is being squeezed, resulting in a denser rock. Heat from deep within the crust -- near the mantle -- softens the dense rock, giving it folding ability. As the Earth's plates collide and move, the pressure forces the rock into new shapes.   6     The third cause is extremely hot, mineral-rich water. Found near magma, this water runs from 570 - 930F. The nearby rocks not only get heated, they either gain minerals or have minerals washed away. Voilá! Once again a rock changes its structure and becomes a new rock! Paragraphs 7 to 9: Name _____________________________ Date ___________________ Rocks Rock! Part 2 1.   Which of these is not a cause of metamorphism?   High heat   Mineral-rich water   Erosion   Pressure 2.   Most metamorphism takes place:   Deep within the Earth   Inside volcanoes   Outside the Earth's crust   In the water 3.   Regional metamorphism occurs under volcanoes.   True   False 4.   Two types of metamorphic rocks exist. They are:   Weathered and Eroded   Igneous and Sedimentary   Foliated and Nonfoliated   Gneiss and Marble 5.   The process through which rocks change is called:   Erosion   Foliating   Rock Life   Rock Cycle 6.   The three types of rock - igneous, sedimentary, and metamorphic - all have something in common. What is it?   They are all foliated.   They are all made from plate boundaries.   They all weather and erode.   They are all nonfoliated.