How many of these words can you explain?

Students will…

• Define metamorphic rocks,

• Describe how they are classified,

and give several examples;

• Describe the factors that influence

the composition and texture

(appearance) of metamorphic rocks,

and how those factors vary within

the earth's crust;

3

Metamorphic Rock Metamorphic rock forms

with temperature and pressure, but remains a

solid .

• Pressure deep within

the earth melts and

changes existing rock.

This is different than

intrusive igneous rock,

because you are

starting with rock, not

magma. The rocks melt

only a little. There are

two different types:

Metamorphic RockMetamorphic rock forms

when pressure deep within the earth melts and changes existing rock. This is different than intrusive igneous rock, because you are starting with rock, not magma. The rocks melt only a little. There are two different types: foliated and non-foliated.

http://www.fi.edu/fellows/payton/rocks/create/metamorph.htm

Meta meaning to change shape Morph meaning form Changes with temperature

and pressure, but remains solid

Metamorphism affects texture and mineralogy

Usually takes place deep in the Earth

Metamorphic Rocks

• Metamorphic rocks are formed by the effect of heat

and pressure on existing rocks.

• This can greatly affect the hardness, texture or layer

patterns of the rocks.

Magma

metamorphic

rockforming

here

heat

Pressure from surface

rocks

Contact Metamorphism – heated by nearby magma Increased temperature changes the composition of

the rock, minerals are changed into new minerals

Hornfels is a fine-grained non-foliated metamorphic rock produced by contact metamorphism

http://www.windows.ucar.edu/tour/link=/earth/geology/meta_contact.html&edu=h igh&fr=t

8

This type of metamorphism occurs when rock is in contact with, or near, a mass of magma (Heat). The changes are caused primarily by the high temperatures of the molten rock, which in effect “bake” the surrounding rock.

Contact

Metamorphism is

indicated by the

“xxxx” in the diagram.

• igneous intrusion metamorphoses "country

rock"

Regional Metamorphism –pressure builds up in rocks that is deep within the Earth

Large pieces of the Earth’s crust collide and the rock is deformed and chemically changed by heat and pressure

http://www.windows.ucar.edu/tour/link=/earth/geology/meta_regional.html&edu=high&fr=t

11

Increase of temperature and pressure with depth (due to the weight of the overlying

rocks) causes rocks to deform and flow as if they were plastic. The minerals within the rock recrystallizeand reorganize to form metamorphic textures

folds or bends

o Index minerals form only at certain

temperatures and pressures

• Index minerals are used to estimate the

temperature, depth, and pressure at which a

rock undergoes metamorphism.

16

Texture of a Metamorphic Rock:

Foliated

Minerals

Gra

nite

Pressure

Gneis

Foliated - contain aligned grains of flat

minerals

Gneiss is foliated metamorphic rock that has a banded appearance and is made up of granular mineral grains.

It typically contains abundant quartz or feldspar minerals.

Non-Foliated – mineral grains are not arranged in plains or bands

Marble is a non-foliated metamorphic rock that is produced from the metamorphism of limestone.

It is composed primarily of calcium carbonate.

Determine if the following rock samples are foliated or non-foliated:

Amphibolite Quartzite Phyllite

All types of rock can changeMetamorphic rocks originally start out as

different types of rocks. Because of

pressure deep within the earth, they

melt and change. Below are a few

metamorphic changes.Granite

becomes

Gneiss

Sandstone

becomes

Quartzite

Shale

becomes

Slate (heat

and

pressure)Shale is a sedimentary rock

22

Granite to Gneiss

Igneous metamorphic

What was the cause?

Heat and Pressure

23

Slate to Phyllite

sedimentary metamorphic

What was the cause?

Heat and Pressure

24

Limestone to Marble

What was the cause?

Sedimentary Metamorphic

Heat and Pressure

5-3-1 Metamorphic Rock page

• Write/ List FIVE words or short phrases

that come to mind when you hear the word

metamorphic rock

3 things that best capture Metamorphic Rock

Next, Rank (number)

your list from most

important (1) to least

important (5)

Copy and finish this statement

using your number one

I understand

that

metamorphic

rock(s) is / are

Write the correct letter

1. What rock type comes from a word meaning to change?

a) Sedimentary Rocks

b) Igneous Rocks

c) Metamorphic Rocks

2. Foliation is:

a) an alignment of mineral grains in a metamorphic rock.

b) alignment of any kind observed in any kind of rocks.

c) layering observed in sedimentary rocks.

3. Metamorphic rocks are classified primarily according to:

a) hardness.

b) chemical composition.

c) texture - the presence/absence of foliation.

4. The principal agents of metamorphism are:

a) compaction and cementation.

b) heat and magma.

c) heat and pressure.