Metamorphic rock Coulter

Types of metamorphic rocks Heat and pressure deep beneath Earth’s surface can change any rock into metamorphic rock. Geologists classify metamorphic rocks according to the arrangement of the grains that make up the rocks.

Foliated rock Metamorphic rocks that have their grains arranged in parallel layers or bands. They split in layers. Foliated rocks include: slate, schist, gneiss Slate comes from heat and pressure changing the sedimentary rock shale. Slate is a denser more compact version of shale.

Nonfoliated rocks The mineral grains in these rocks are arranged randomly. These do not split in layers. Marble and quartzite are two metamorphic rocks that are non-foliated. Quartzite comes from sandstone. The quartz particles recrystallize to form quartzite.

Rock cycle Forces deep inside Earth and at the surface produce a slow cycle that builds, destroys, and changes the rocks in the crust. Is a series of processes on Earth’s surface and in the crust and mantle that slowly change rocks from one form to another.

Beginning In the case of stone mountain, the rock cycle began millions of years ago. First a huge piece of granite formed underground. Then the mountain building slowly pushed the granite upward. Over millions of years weathering and water began to wear away the granite, forming sediment.

Continuing Over millions of years, layers of sandy sediment pile up on the ocean floor. Slowly the sand will compact by its own weight. Dissolved calcite will cement the particles together. Eventually that granite will form into sandstone, a sedimentary rock.

Continuing More and more sediment will pile up on the sandstone. As it becomes buried pressure will increase. The rock will become hot. Silica will replace the calcite holding the rock together and the texture will change from gritty to smooth. After millions of years the sandstone will change into quartzite (metamorphic rock)

Rock cycle