Notes Metamorphic Rock

How can a rock change into another kind of rock? Think About… How can a rock change into another kind of rock?

Heat and Pressure When you cook popcorn, you use heat to increase the pressure in the kernels until they explode.

Heat and Pressure Popcorn is one example of how things can change because of heat and pressure.

Heat and Pressure Metamorphism is the process in which a rock is transformed by heat or pressure-or both.

The original rock is called the parent rock. Heat and Pressure The original rock is called the parent rock. The resulting rock is a metamorphic rock.

Heat and Pressure Example: Shale is a parent rock that can become the metamorphic rocks slate, phyllite, schist, and gneiss. Parent rock: Shale Metamorphic rocks: Slate Phyllite Schist Gneiss

Heat and Pressure Igneous, sedimentary, and even metamorphic rocks can all be parent rocks for metamorphic rocks. Marble Limestone

During metamorphism, rocks undergo many changes. Heat and Pressure During metamorphism, rocks undergo many changes. Pressure causes a rock’s minerals to flatten out.

Melting and cooling ALWAYS produces igneous rock! Heat and Pressure Rocks do NOT melt during metamorphism, even though they experience high temperatures. Melting and cooling ALWAYS produces igneous rock!

Heat and pressure break the bonds between the atoms. Recrystallization is when the atoms re-bond differently after they are broken.

Recrystallization can result in: Heat and Pressure Recrystallization can result in: Crystals growing larger New minerals forming

Metamorphic Changes The changes in a metamorphic rock depend on the type of parent rock and the amount of temperature and pressure.

The deeper in the crust, the greater the metamorphic changes. Example: Shale near the surface becomes slate, while shale deep in Earth becomes gneiss.

Foliation Foliation is an arrangement of minerals in flat or wavy parallel bands.

Foliation happens when rocks are under pressure. Rock that is made of only one mineral will not show foliation.

At low levels of metamorphism, the bands of minerals are thin. Foliation At low levels of metamorphism, the bands of minerals are thin.

Slate can be split into thin sheets. Foliation Slate can be split into thin sheets.

With higher pressure and temperature, the rock will look shiny. Foliation With higher pressure and temperature, the rock will look shiny.

Foliation At even higher temperature and pressure, the rock separates into light and dark bands.

Non-Foliated Rocks Metamorphic rocks that do not have foliation are called non-foliated rocks.

A rock might be non- foliated because it is only made of one mineral. Non-Foliated Rocks A rock might be non- foliated because it is only made of one mineral. Example: Marble is made of limestone, which is made of calcite.

Non-Foliated Rocks A rock might be non- foliated because it has not experienced high pressure. Example: Hornfels forms from rocks being heated by without melting.

Which kind of rock forms by recrystallization? Intrusive igneous Review Which kind of rock forms by recrystallization? Intrusive igneous Extrusive igneous Sedimentary Metamorphic

Review 2. An existing rock can change into another kind of rock when it is subjected to great Pressure Winds Flooding Foliation