THREE CLASSIFICATIONS OF ROCKS

Rocks: a mixture of minerals and other materials. They are

classified by how they form. The three types of rocks are igneous, sedimentary, and metamorphic.

IGNEOUS ROCK- Formed after volcanoes erupt!!!

- Igneous comes from the Latin word “ignis” meaning “fire.”

The OLDEST TYPE of all rocks.

- Boiling magma comes to the Earth’s surface, cools, and turns to solid rock.

IGNEOUS ROCK

•Igneous rocks are formed from the cooling and hardening of molten material called magma (if below the surface) or lava (if above the surface).

IGNEOUS ROCK:•Two Types 1. Extrusive - Forms from lava on the surface - Cools quickly, so it has small crystals (texture

is fine-grained). 2. Intrusive - Forms from cooled magma below the surface (inside the volcano).• - Cools slowly, so it has large crystals. (texture

is coarse-grained).

IGNEOUS ROCK

•Examples: ▫Granite-intrusive (rough)

▫Obsidian-extrusive (smooth)

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CHARACTERISTICS OF IGNEOUS ROCK

•Usually has no layering.•Usually made up of two or more minerals.•Usually made of mineral crystals•May be fine grained or glassy

Summarize Igneous Rocks in

21 words1.How are Igneous rocks

formed?2.How do extrusive rocks

form?3.How do intrusive rocks

form?

SEDIMENTARY ROCK

APPROXIMATELY 70% OF ALL THE ROCKS ON EARTH’S SURFACE ARE SEDIMENTARY ROCKS.

SEDIMENTARY ROCK•Formed when pieces (sediments) of other rock or remains of plants and animals are pressed and cemented together.

SEDIMENTARY ROCK•Process that forms sedimentary rock—

1. Weathering – breaking down of rock material into smaller pieces - SEDIMENT2. Erosion-occurs when running water or wind carry away soil and rock particles.

▫MOVING (transportation)

SEDIMENTARY ROCK•Process that forms sedimentary rock—

3. Deposition-soil and rock drop out of wind and water as sediment (small pieces of rock or living things) and are laid down in a new place.▫LAYING DOWN & BUILDING UP

SEDIMENTARY ROCK•Process that forms sedimentary rock—

4. Compaction-new layers of sediment press down on the old layers over long periods causing them to squeeze together tightly.▫PRESSURE

SEDIMENTARY ROCK•Process that forms sedimentary rock—

5. Cementation-minerals dissolve in water between the layers, crystallize and glue particles of sediment together permanently.▫GLUE

When sediments are pressed (compaction) and glued

together (cementation) it is called lithification.

SEDIMENTARY ROCK•Most commonly found in layers.

•Example: Sandstone

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CHARACTERISTICS OF SEDIMENTARY ROCK•Often contains fossils•Layers, originally flat, but can become curved

over time because of the shifting forces acting on Earth’s crust.

•Has great color variety•Usually composed of pieces cemented or

pressed together.

What I thought you taught about

Sedimentary Rocks

METAMORPHIC ROCK

The oldest known rock lies in Canada. The Acasta Gneiss, a metamorphic rock, is 3.96 billion years old.

METAMORPHIC ROCKHeat AND Pressure can

change many things. They can even change rocks!!

1.Comes from the Greek root “meta” (change) and “morphosis” (form). Think about how caterpillars go through metamorphosis and CHANGE into a butterfly!

METAMORPHIC ROCK2. Metamorphic rock forms deep beneath Earth’s surface when extreme heat from high temperatures, great pressure, and chemical reactions cause one type of rock to change into another type of rock. The rocks change in appearance, texture, crystal structure and mineral content.3. The heat comes from magma.4. The pressure comes from the layers of rock piled on top of layers and layers of other rock. The layers on the bottom get squeezed.

CHARACTERISTICS OF METAMORPHIC ROCK

•Classified by texture and chemical composition (what minerals is it made up of). Metamorphic rocks are classified into two types:

1. Foliated: grains are arranged in parallel (layers) lines or bands ex: gneiss 2. Non-Foliated: grains are arranged randomly May have foliated layers that are created when

the mineral composition of the rock gets changed

due to heat and pressure

METAMORPHIC ROCK•Metamorphic rocks can form from igneous, sedimentary or other metamorphic rocks.

•Example: Granite Gneiss

METAMORPHIC ROCK

Sandstone Quartzite

METAMORPHIC ROCKShale Slate

METAMORPHIC ROCK

Limestone Marble

Admit what you know about Metamorphic

Rocks