What is Geology?
The study of the forces
that change the earth’s
surface.
These forces can either
build up (constructive) or
wear down (destructive)
the earth’s crust.
Constructive forces
Forces that build up the earth.
Example: Volcanic eruptions
add new landmass
http://english.peopledaily.com.cn/200607/21/eng20060721_285295.html Mayon volcano, Philip
http://top-10-list.org/2009/04/20/top-10-worst-volcanic-eruptions/ Mt. Krakatoa, Indionesia
Destructive forces
Forces that wear away the
earth’s surface.
Example: Weathering and erosion
caused by wind or water.
Grand Canyon, USA
Main layers that make
up Earth
1. Crust
2. Mantle
3. Outer Core
4. Inner Core
Earth’s Crust
•The layer of the earth that
forms the outer “skin”
•Includes both continental
land and the ocean floor
Oceanic crust forms
beneath the ocean
and is made from…
BASALT
http://www.pitt.edu/~cejones/GeoImages/2IgneousRocks/IgneousCompositions/3Basalt/BasaltSmallVesicOlPheno.jpg
http://www.explorevolcanoes.com/volcanoimages/spreading%20ridge%20Press%20and%20Siever.jpg
Continental crust
forms above the
ocean and is made
mostly from …
GRANITE
http://www.earth.ox.ac.uk/~oesis/field/medium/granite1.jpg
http://images.google.com/imgres?imgurl=http://www.beg.utexas.edu/mainweb/publications/graphics/granite400.jpg&imgrefurl=http://www.beg.utexas.edu/mainweb/publications/graphics/granite.htm&usg=__0de5K-fYX3ZSELLMQs78BEQCxqI=&h=300&w=400&sz=78&hl=en&start=1&um=1&itbs=1&tbnid=KHAn81OWrYHiM:&tbnh=93&tbnw=124&prev=/images%3Fq%3Dgranite%26hl%3Den%26sa%3DN%26um%3D1
Density and Thickness of
Earth’s Crust
• Continental crust is thicker but
less dense than oceanic crust
• Oceanic crust is thinner but
more dense than continental
crust
Earth’s Mantle
• A layer of hot rock material located
beneath the crust.
• More than 82% of Earth’s volume at about
2,900 km thick.
• Divided into two main layers.
–Upper mantle is made up of the lithosphere and
asthenosphere
–Lower mantle
The Lithosphere
•A layer of rigid rock that
includes all of the Crust and
the upper portion of the Mantle.
•It’s about 100 km thick
The Asthenosphere
•A layer of solid rock that
behaves like “plastic” (a flowing
solid; gooey).
• Found in the Mantle beneath
the lithosphere.
•The lithosphere floats on top
of the asthenosphere.
Earth’s Core
• The inner core and the outer core
together make up the structure of the
Earth’s core
• Both the outer and inner cores are
composed of iron and nickel
• The outer core is liquid metal, and the
inner core is solid metal
How do geologists know the
structure inside the Earth?
Because the actual interior of
Earth cannot be seen,
geologists use indirect
observations.
What is indirect evidence?
Indirect evidence is evidence
that you get without actually
seeing or touching the object
you are studying.
What are seismic waves?
Waves of energy generated
by earthquakes.
Composition…
State of Matter…
rock
metal
solid, rigid
solid, plastic
solid, rigid
liquid
solid, rigid
(gooey)
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