Transcript Chapter 4 rocks

Chapter 4
Rocks
What is a rock?
A rock is a mixture of
minerals, minerialoids,
glass or organic matter.
Types of Rocks
•Sedimentary
•Igneous
•Metamorphic
How are rocks formed?
• 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
1400oC.
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.