The Changing Earth

13.3 How rocks change

• Rocks are formed when lava or magma

solidifies.

• These rocks can become other kinds of

rocks when they are broken down then

cemented together with other sediment, or

changed by heat and pressure.

13.3 How rocks change

• Sedimentary rocks

are formed from

pieces of broken

down rock.

• Sedimentary rocks

are the most

common rocks found

on Earth’s surface.

13.3 Sedimentary Rocks

• Sedimentary rocks are identified by

the size of the particles that form

them.

1. mudstone

2. sandstone

3. conglomerate

13.3 Sedimentary

Rocks

• Most fossils are found

in sedimentary rock

layers.

• Sedimentary rocks hold

clues to the past.

Where might organisms get

covered by sediments?

13.3 Metamorphic Rocks

• A metamorphic

rock is a rock formed

from another kind of

rock due to heat and

pressure.

• Metamorphism

means to change the

form of something.

13.3 Metamorphic rocks

• When magma comes in

contact with another type of

rock, the high heat may form

metamorphic rock near the

point of contact.

• This is called contact

metamorphism.

13.3 Metamorphic rocks

• Limestone is a rock

made of shells.

• During contact

metamorphism

limestone becomes

marble under heat

and pressure.

13.3 Metamorphic rocks

• High-grade metamorphisminvolves high pressure and either low or high temperatures.

• In this process, the minerals in a rock change to form new minerals.

13.3 Metamorphic rocks

• Heat and pressure result when colliding continents form mountains at a convergent boundary.

• Mountains are where we find metamorphic rocks.

13.3 Metamorphic rocks tell great

stories

• Geologists use rocks

as clues to understand

the history of Earth.

13.3 The rock cycle

• The rock cycle

allows rock to

keep changing

form and move

from place to

place on Earth.