NSSS5.5

toc =5.5 Metamorphic Rocks=

Vocabulary

 * foliated**: The thin flat layer which can be found in a metamorphic rock. Foliated means //leaf// in Latin.

How Metamorphic Rocks Form

 * Deep beneath the Earth's surface, heat and pressure can change any rock into a metamorphic rocks
 * When a rock undergoes the changes to become a metamorphic rock, its appearance, texture, crystal structure and mineral content change as well
 * The rock goes down to the mantle when collisions between the Earth's crust force down rock
 * The deeper the rock goes, the greater the pressure on the rock
 * The rock which is under hundreds or thousands the times the pressure then on the surface can change the minerals in a rock

Classifying Metamorphic Rocks

 * When the metamorphic rocks are forming, the pressure also occurs on the rock's grains
 * Tremendous pressure can cause the grains to line up in straight parallel lines
 * This is how geologists classify metamorphic rocks
 * The grains which are in parallel layers are said to be foliated
 * Foliated rocks split easily along the bands
 * Ex. shale
 * When shale is under heat and pressure, it transforms into slate
 * In the process, hornblende and mica form
 * Some metamorphic rocks are not foliated
 * Non-foliated rocks do not split at the bands
 * Marble and