Metamorphic rocks-Hockersmith

Metamorphic rocks

MetamorphicFormation

Imagine that you left home with a cheese sandwich in your backpack. You threw your backpack into your hot locker at school. Would the sandwich look the same by lunchtime? The cheese would likely be soft because of changes in temperature. Also, your heavy backpack could squish the sandwich. Like the sandwich, metamorphic rocks are affected by changes in temperature and pressure. 

Where do they form?

Most metamorphic rocks form far below Earth’s surface. Deep within Earth’s crust and mantle, temperatures and pressures are high. Metamorphic rocks, like igneous rocks, form under high temperature and pressure conditions. Unlike igneous rocks, metamorphic rocks do not crystallize from magma/ They bend and form layers during their formation

Multiple Choice

Where do most metamorphic rocks form?

• mantle and core

• inner core and outer core

• crust and mantle

• surface

How are they different than Sedimentary?

Sedimentary rocks form ON earths surface

Metamorphic rocks form BENEATH earths surface

Erosion and deposition= sedimentary

heat and pressure= metamorphic

When rocks undergo heat and pressure, they behave like Plastic.

-The rocks can bend and fold, WITHOUT melting(remember if something melts its magma>igneous rock.

-A permanent change in shape by bending and folding is called plastic deformation.

-Bending and folding rocks is common during the formation of plate tectonics, when plates come together and form mountains

How are metamorphic rocks classified?

When classifying a metamorphic rock, we look at its texture and its mineral composition

Types of Metamorphic Rocks

There are two types

-Foliated

-Non Foliated

Foliated Metamorphic rocks

Foliated rocks contain parallel layers of flat and elongated minerals. Often, the layers are different colors. The layers develop from an uneven distribution of pressure during metamorphism. Foliation is a common feature of metamorphic rock. 

Multiple Choice

What is the main physical characteristic of a foliated metamorphic rock?

• big crystals

• layers

• nothing

• very small non existent crystals

Non Foliated Metamorphic Rocks

Nonfoliated rocks are metamorphic rocks that have mineral grains with a random, interlocking texture. In nonfoliated rocks, the minerals do not line up. Instead, the crystals are shaped like blocks and are all about the same size. The minerals are generally the same color, which helps distinguish them from igneous rocks such as granite. 

Multiple Choice

Non foliated rocks crystals are said to be

• apart

• in layers

• interlocking

• dark