rocks

Rocks

There are three categories of rocks

• Igneous rocks • Sedimentary rocks• Metamorphic rocks

Igneous Rock

Vocabulary

• _________- molten rock beneath the earth’s surface

• ________- small holes made from solified gas bubbles

• __________- the molten rock that reaches the earth’s surface

• ___________- rough • ____________- lava flows out and hardens • ______________- when magma harderns inside

the earth

Igneous Rocks Definition

• Igneous rocks are formed from the solidification (making hard) and crystallization of molten rock. – This makes the rocks

hard, solid and compact.

Two Types of Molten Rocks

• Magma – is the molten rock beneath the Earth’s surface

• Lava is the molten rock that reaches the Earth’s surface

• When magma or lava cools and solidifies it forms igneous rocks– As the liquid rocks

gets harder crystals may form

• This gives the igneous rocks it’s texture

Two types of Igneous Textures

• The texture of igneous rock is dependent (relies) the rate (speed) of cooling. – Slow cooling bigger

crystals • Coarser (rougher)

texture

– Rapid cooling smaller crystals

• Finer texture

Vesicular

• When bubbles of gas are in solidified lava there are gas holes called Vesicles – Igneous rocks that

have these holes are said to be vesicular.

Cooling , Temperature, & Pressure

• Cooling is related to both temperature and pressure – When the temperature

drops rapidly or pressure is lessened you are going to have less crystals and a finer texture.

– This is usually with molten rocks closer to the earth’s surface or lava on top of the surface.

What are extrusive and intrusive Igneous

rocks?

Extrusive Igneous rocks

• Extrusive – when the lava exits the earth’s

surface and hardens.

- since it is cooler and less pressure exists on the surface the rocks are finer and have less crystals.

Exit –leave outside

Intrusive Igneous Rocks

• Intrusive when the magma hardens inside the earth. – since there is more

pressure and heat the deeper you go into the Earth

• the larger the crystals and the courser (rougher) the texture of the rock is

IN

Let’s recap!How do Igneous

rocks form

Through the solidification and crystallization of

magma and lava!

How does magma form?

Minerals must be melted Some like mica melt under very low temp and other needs a

higher temp to melt

Igneous rock scheme ( ESRT)

• This chart is used to help us identify What type of Igneous rock it is.– It shows us

• Color• Texture• Density • Mineral composition

Where are igneous rocks found?

All overThey are in oceans, continental rocks

Ocean Continental

Mafic Low density rocks

Basalt Graphitic

High density Felsic