metamorphic rocks

metamorphism

Metamorphic rocks start off as some kind of rock. The starting rock can be igneous, sedimentary or even another metamorphic rock. Heat and/or pressure then change the rocks physical or chemical makeup. During metamorphism a rock may change chemically. Ions move and new minerals form. The new minerals are more stable in the new environment. Extreme pressure may lead to physical changes like foliation. Foliation forms as the rocks are squeezed. If pressure is exerted from one direction, the rock forms layers. This is foliation. If pressure is exerted from all directions, the rock usually does not show foliation. There are two main types of metamorphism: 1. Contact metamorphism results when magma contacts a rock, changing it by extreme heat (Figure 4.14). 2. Regional metamorphism occurs over a wide area. Great masses of rock are exposed to pressure from rock and sediment layers on top of it. The rock may also be compressed by other geological processes. Metamorphism does not cause a rock to melt completely. It only causes the minerals to change by heat or pressure. Hornfels is a rock with alternating bands of dark and light crystals. Hornfels is a good example of how minerals rearrange themselves during metamorphism (Figure 4.14). The minerals in hornfels separate by density. The result is that the rock becomes banded. Gneiss forms by regional metamorphism from extremely high temperature and pressure.

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uses of metamorphic rocks

Quartzite and marble are the most commonly used metamorphic rocks. They are frequently chosen for building materials and artwork. Marble is used for statues and decorative items like vases (Figure 4.16). Quartzite is very hard and is often crushed and used in building railroad tracks. Schist and slate are sometimes used as building and landscape materials.

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instructional diagrams

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questions

type of metamorphism in which magma contacts a rock and changes it by extreme heat

a. regional metamorphism

b. metamorphic rock

-->  c. contact metamorphism

d. hornfels

e. foliation

f. marble

g. quartzite

Metamorphism occurs when there is

a. heat only

b. pressure only

c. heat and pressure together

-->  d. all of the above

Any rock formed by extreme heat and pressure

a. regional metamorphism

-->  b. metamorphic rock

c. contact metamorphism

d. hornfels

e. foliation

f. marble

g. quartzite

Metamorphic rocks change

a. physically only

b. chemically only

c. physically and chemically together

-->  d. any of the above

metamorphic rock with alternating bands of light and dark crystals

a. regional metamorphism

b. metamorphic rock

c. contact metamorphism

-->  d. hornfels

e. foliation

f. marble

g. quartzite

Contact metamorphism is caused by

-->  a. heat from magma

b. water pressure

c. the weight of overlying rock

d. atmospheric pressure

Metamorphism changes rocks because

-->  a. the minerals need to be stable under new conditions

b. the rocks melt

c. atoms break apart to form new atoms

d. the pressure causes foliation in each mineral

type of metamorphism in which great masses of rock are exposed to extreme pressure

-->  a. regional metamorphism

b. metamorphic rock

c. contact metamorphism

d. hornfels

e. foliation

f. marble

g. quartzite

formation of layers in some metamorphic rock

a. regional metamorphism

b. metamorphic rock

c. contact metamorphism

d. hornfels

-->  e. foliation

f. marble

g. quartzite

Regional metamorphism can be the result of

a. extreme heat

b. fluid infiltration

-->  c. intense pressure from all directions

d. melting

metamorphic rock that is crushed and used to build railroad tracks

a. regional metamorphism

b. metamorphic rock

c. contact metamorphism

d. hornfels

e. foliation

f. marble

-->  g. quartzite

metamorphic rock that is used to make statues

a. regional metamorphism

b. metamorphic rock

c. contact metamorphism

d. hornfels

e. foliation

-->  f. marble

g. quartzite

Foliation occurs when pressure is exerted from all directions equally.

a. true

-->  b. false

Regional metamorphism may expose rocks to high pressure and low temperature.

-->  a. true

b. false

A metamorphic rock can be metamorphosed.

-->  a. true

b. false

A metamorphic rock nearly always resembles its original parent rock.

a. true

-->  b. false

Metamorphic rocks can always be distinguished from igneous and sedimentary rocks because they are

a. true

-->  b. false

When a rock undergoes metamorphism, it becomes an entirely new type of rock.

-->  a. true

b. false

During metamorphism, ions may move and new minerals may form.

-->  a. true

b. false

There are two types of metamorphism.

-->  a. true

b. false

Contact metamorphism causes rock to melt and form magma.

a. true

-->  b. false

The most commonly used metamorphic rocks are slate and gneiss.

a. true

-->  b. false

Quartzite is a relatively soft metamorphic rock.

a. true

-->  b. false

Gneiss forms by contact metamorphism.

a. true

-->  b. false

Schist is sometimes used as a landscaping material.

-->  a. true

b. false

In the 1500s, Michelangelo carved statues from marble.

-->  a. true

b. false

Metamorphic rocks cannot undergo further metamorphism and change to different types of rocks.

a. true

-->  b. false

During metamorphism, rocks may change

a. chemically.

b. physically.

c. permanently.

-->  d. two of the above

Metamorphism begins with

a. magm

b. sediments.

c. lava.

-->  d. rock.

What type of change in rock is foliation?

-->  a. physical change

b. chemical change

c. mineral change

d. two of the above

A metamorphic rock may undergo foliation when pressure is

-->  a. exerted from just one direction.

b. exerted from all directions.

c. relatively weak.

d. absent.

Slate is a metamorphic rock that is used for

a. building.

b. landscaping.

c. statues.

-->  d. two of the above

Which of the following types of rocks can undergo metamorphism?

a. sedimentary rock

b. igneous rock

c. metamorphic rock

-->  d. all of the above

All of the following are metamorphic rocks except

a. schist.

b. quartzite.

c. gneiss.

-->  d. granite.

diagram questions

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