WHAT ARE ROCKS? ROCKS are a naturally occurring

SOLID MIXTURE of one or

more minerals and organic

matter.

Rocks are ALWAYS changing.

How do we

classify Rocks?

Formation (where and how

the rock was formed)

Texture (grainy, glassy)

Composition (what

minerals make up the rock)

What are Igneous

Rocks?

From the Latin word igni (fire)

Form from the cooling of

molten rock (lava and magma).

The most abundant type of

rock.

Classified according to their

origin and composition.

Classification 1

ORIGIN— Where are Igneous Rocks are formed

How does Extrusive Igneous Rocks form?

(Think Exit)

Extrusive Rock is formed from lava erupted onto Earth’s surface.

Exits the Earth- thus it is lava that is cooling.

Cools quickly before large crystals can form.

Will have fine-Grained, small crystals.

Extrusive rocks are smooth

Ex. (Basalt)

How does

Intrusive

Igneous Rocks

form?

(Think inside)

Intrusive Rock is formed when magmahardens beneath Earth’s surface.

Magma cools slowly inside of the earth.

Slow cooling causes the formation of Coarse-Grained rocks with large crystals.

Intrusive rocks usually have a rough texture.

Ex. Granite

What is Lava?

What is Magma?

molten material found on the surface of the earth.

molten material found beneath the surface of the earth.

• Obsidian has a glassy texture

• Rhyolite has a fine-grained texture

What does Mafic

describe?

What does Felsic

describe?

Mafic describes dark colored igneous rocks.

Mafic rocks have a low amount of silica, but a higher amount of iron, magnesium, or calcium.

Felsic describes light colored igneous rocks.

Felsic rocks contain a high amount of silica.

What are

sedimentary

rocks?

Rocks made from sediments that are pressed or cemented together or when sediments precipitate out of a solution.

Sedimentary rocks represent 7% of the Earth’s crust, but they cover 70% of the Earth’s surface.

There are 3 types of sedimentary rock.

Sedimentary rocks are fossil-carrying rocks.

What are

sediments ?

Rock fragments, mineral grains, animal & plant remains-shells, bones, leaves, stems

Where do

Sedimentary rocks

form?

Visual Clues that it

is sedimentary rock.

Form at or near the surface of the earth = no internal heat

The rock will have layers (strata)

What are Strata?

Horizontal layers found in sedimentary rocks.

Layers at the top are the youngest (newest), layers at the bottom are older.

Newer layers

Older layers

How does

Sedimenta

ry rock

form?

W

Weathering

the breaking down of material by

wind, water, ice, sunlight, & gravity

E

Erosion Movement of sediment

D

DepositionWhere the sediment is deposited.

C

Compaction

As new layers of sediment occur,

the weight of the new layers can

squeeze the older sediment tightly

together. (mush)

C

Cementation

Dissolved minerals flow between

the particles and glue them

together

Classification 2

Formation— How are Sedimentary rocks formed.

There are 3 types of Sedimentary Rock

What are

the three

types of

sedimentary

rock?

Clastic: (Rock & mineral fragments compacted & cemented together)

Chemical: (solutions of dissolved minerals & water)

Organic: Form where the remains of plants and animals are deposited in thick layers (Contain remains, fossils of ocean animals)

What is

metamorphic

rock?

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.

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.

How are

metamorphic

rocks

classified?

Foliated—mineral grains are flattened and line up in parallel bands.

Non-Foliated—No bands are formed.

Foliated Non Foliated