Metamorphic Rocks

and how they form.

Metamorphic RocksMeta = Change

Morph = Form

Igneous or sedimentary rocks that have been changed into other rocks by heat (100 to 800°C) and/or pressure (10,000 to 20,000 times normal atmospheric).

Examples:Gneiss, Hornfels, Marble, Schist, Slate, Soapstone, & Quartzite,

Metamorphic Rocks

How do sedimentary and igneous rocks change?

Metamorphic rock can be made by two different processes:

– Regional Metamorphism– Contact Metamorphism

Due to the action of the heat and pressure of these two processes, metamorphic rocks are:

1. the densest rocks,2. rarely have holes, pores, or

fossils,3. have a blend of fewer minerals.

Metamorphic Rocks

Regional Metamorphism: •When huge areas of rock change due

to intense pressure (heat is often involved, also).

•Regional metamorphism only happens during mountain building movements when pressure on rocks in the ground is highest.

•OCCURS OVER VERY WIDE AREAS!

•The metamorphic rock in our crust is made this way (ex: marble, quartzite)

Models of Regional Metamorphism

Models of Regional Metamorphism

Metamorphic Rocks

Contact Metamorphism:•This process occurs when hot magma forces its way into overlying rock.

•The heat of the magma bakes the overlying rocks and the rocks surrounding the magma.

•The width of the affected area is dependant on the temperature of magma (hotter = wider).

•The changes ARE NOT as drastic as regional metamorphism.

Models of Contact Metamorphism

Models of Contact Metamorphism

Metamorphic Rock Formation in Action

Metamorphic Rocks

Shale Slate

Metamorphic Rocks

Sandstone Quartzite

Metamorphic Rocks

Limestone Marble

The Rock CycleThe Rock Cycle:•The changing of rocks from one

form to another through volcanism, weathering, erosion, burial, lithification, and/or metamorphism.

•Any and all rocks can get melted into magma, or broken into sediments, or metamorphosed into a different rock.

Ticket to Leave

Copy the following image on a separate piece of paper and turn in the finished sketch before you leave the class.