Metamorphic rocks form from intense heat and pressure that alter igneous, sedimentary, or existing metamorphic rocks. This process occurs deep underground where overlying rock layers exert pressure and heat is present but not enough to melt the rock. Minerals may rearrange or new minerals may form as the rock changes form. Metamorphic rocks are classified as either foliated, with flattened and aligned mineral grains, or non-foliated with no banded structure. They typically form near mountain ranges where tectonic plates collide or where thick piles of overlaying rock cause high pressure.

1. METAMORPHIC ROCK

2. • Rocks that have changed due to intense
temperature and pressure
• “Meta” means “change” and morphosis means “form”
in Greek
• Igneous, sedimentary and other metamorphic rocks
can change to become metamorphic rocks

3. What occurs in the Earth to change
these rocks?
• Pressure from overlying rock layers
• High heat, but not enough to melt the rock
• Rocks may be flattened or bent or atoms may be exchanged to
form new minerals.

4. • *You can think of metamorphic rocks as a squished
peanut butter & jelly sandwich in your lunch.

5. How are metamorphic rocks classified?
• Foliated—mineral grains are flattened and line up in
parallel bands
• Example: gneiss formed from rearrangement of
minerals in granite into bands

6. How are metamorphic rocks classified?
• Non-Foliated—No bands are formed
• Example: marble formed from limestone

7. Where do metamorphic rocks usually form?
• Where magma intrudes
relatively cool rock
• Near colliding plates (near
mountain ranges)
• Places that are covered miles
thick with other rock causing
pressure
• When hot water intrudes rock
• Where a meteorite strikes
Earth (rare)
• Where lightning bolts strike
rocks (rare)