• Rocks are formed through a series of processes that transforms Earth materials back and forth from the three types of rocks.
• This process is called the rock cycle.

ROCK CYCLE
• Shows the three types of rock and they are formed.
• Factors involved in rock formationweathering, erosion, heat, pressure
• Processes that form rock – compaction, cementation, melting, cooling
• Ever-changing processes moving from one type of rock to another.

IGNEOUS ROCKS
• Rocks that are formed either molten material from a volcano or from deep inside the Earth’s surface.

Two Types of molten material
• Lava
• Magma
Both can reach temps of
1400 o C.

What is Lava?
• Lava - the molten material that reaches the Earth’s surface after a volcanic eruption. It is pushed to the surface due to intense heat and pressure.
• The outside air or water cools the materials forming rocks
.

What is magma?
• Magma – molten material found beneath the Earth’s surface.
• Found about 60km to 200 km below the surface.
• Radioactive elements and intense pressure melts rocks forming magma.
• Less dense than the solid rock so it pushed to the surface.

Two types of igneous rock
• Intrusive – rocks that are formed from magma beneath the Earth’s surface.
• Extrusive – rocks that are formed when lava cools on or near the
Earth surface.

Intrusive Igneous Rocks
• Formed from large mineral grains
• Are found when rock and soil are removed or when it pushed to the surface or forces in Earth have pushed them to the surface.

Extrusive Igneous Rocks
• Lava flows to the surface of the
Earth and is cooled by air or moisture.
• Cools quickly so mineral grains are small.
• Typically fine-grained in texture.

Classification of Igneous Rocks
• Igneous rock is classified by the three magma that formed them.
• Three types of magma is basaltic, granitic, and andesitic.

Basic Igneous Rock Textures
• Fine – grained: Crystals too small to be seen without the unaided eye.
• Coarse- grained: Crystals large enough to be seen by the unaided eye
• Glassy: Brittle glossy crystals due to quick cooling.
• Porphyritic: Large crystals embedded in a cluster of small crystals.

Weathering
• Day-in and day-out influences of the atmosphere.
• Changing temperature, Wind, Humidity, and organic matter.
• Causes slow disintegration and rock decomposition.