Download Unit 17 STRUCTURE OF THE EARTH

Unit 17
STRUCTURE OF THE EARTH
What are the different types of
rocks?
IGNEOUS ROCKS
• formed from molten rocks (magma) that
flow to the Earth’s surface (lava) when a
volcano erupts
• comes from the word “ignite” meaning fire
2 Types of Igneous Rocks
INTRUSIVE IGNEOUS
• formed underground or beneath the Earth’s
surface
• formed when magma cools and solidifies
slowly
• have large crystals and are coarse-grained
because the crystals have enough time to
grow to a large size
• ex. - granite
EXTRUSIVE IGNEOUS
• formed on the Earth’s surface
• formed when lava cools and solidifies quickly
• have smaller crystals and are fine-grained
because they do not have enough time to
grow in size
• ex. - basalt
EXAMPLES OF IGNEOUS ROCKS
GRANITE
BASALT
SEDIMENTARY ROCKS
• formed when grains or “sediments” of
weathered rocks (rocks broken into
smaller pieces by different physical and
chemical means) are pressed and
cemented together by dissolved minerals
• may contain fossils
• ex. – sandstone, limestone, shale,
conglomerate, breccias
LIMESTONE
SHALE
SANDSTONE
FORMATION OF FOSSILS
• fossils are remains
of animals and
plants that lived
long ago
• preserved in
sedimentary rocks
METAMORPHIC ROCKS
• formed when igneous and sedimentary rocks
change their structures under intense heat
and pressure
• comes from the word “metamorphosis” which
means change
• ex. – slate, from sedimentary shale rock
- marble, from sedimentary limestone
rock
- schist, from igneous basalt rock
EXAMPLES OF METAMORPHIC
ROCKS
GNEISS
SCHIST
ROCK CYCLE
STRUCTURE OF THE EARTH
CRUST
• thinnest, top layer between 0-50 km thick
• made up of many separate pieces called
plates
• forms the Earth’s surface or the ground
MANTLE
• beneath the crust made up of molten rocks
called magma (formed due to high
temperatures beneath the mantle)
• makes up the greatest volume of the
Earth’s structure (about 2900 km thick)
CORE
• innermost layer which is very hot
• made up of solid iron and nickel
• the core’s heat causes the rocks in the
mantle to be in the liquid state
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http://www.ontariogeoscience.net/keyconceptitems/rockcyle.jpg
http://mulch.cropsoil.uga.edu/soilsandhydrology/images/Granite.jpg
http://www.imageafter.com/dbase/images/nature_extinct/b20nature_extinct0
05.jpg