Transcript Earth`s Structure

Geology
Geology-Study of the Earth and it’s
processes; includes rocks and minerals,
earthquake study and vulconology, and
geologic time and fossils.
Earth’s Structure
Lithosphere: outermost rigid layer of the
Earth; made of crust and rigid upper part of
mantle
Asthenosphere: soft layer of the mantle on
which parts of lithosphere move.
Mesosphere: strong, lower part of mantle
Outer Core: liquid
Inner Core: solid; both parts iron with some
nickel
How do we know?
Scientists have used seismic evidence
(earthquake waves) to detect what is
inside the Earth. As the waves move
and change inside, we can measure
their changes to determine the
materials the waves are passing
through or bouncing off of.
Earth Has Faults (Doesn’t
Everybody?)
The Earth’s crust and the upper mantle
are broken into fragments called plates.
Plates interact and cause geologic
features and events.
When movement occurs due to this
activity, it occurs along joints in the
plates called faults.
Tennessee’s Faults
Tennessee sits in between three geologically
active faults: The New Madrid fault, which is
in 5 states including W. TN along the
Mississippi; and the Appalachians, which
experience minor quakes every year. The
New Madrid is a major fault line that caused
the formation of Reelfoot Lake during a series
of major earthquakes in 1811-1812.
Tennessee's History
Other Earthquakes of Note
Earthquake Information for California
1989- Quake in CA caused major damage in
Bay Area (San Fran. And Oakland); 63 deaths,
thousands of injuries, $6 billion in damage;
largest EQ on San Andreas fault since 1906
Prince William Sound, Alaska 1964 March 28
9.2 EQ, causing up to 67 m waves in Valdez,
large amount of property damage and a
tsunami that traveled all the way to Hawaii and
cause ripple effects as far as Puerto Rico
Alfred Wegener and Plate
Tectonics
Wegener proposed hypothesis of continental
drift in 1915; he was a meteorologist.
He named the large landmass Pangaea,
meaning “all earth”.
His evidence included: fossils of Glossopteris
and Mesosaurus, matching mountain chains
on different continents, and similar climate
changes on landmasses.
Sea-Floor Spreading
New ocean crust is formed at midocean ridges as melted material from
the mantle is deposited on the sea-floor.
As this occurs, alternating bands of
magnetism are found at either side of
the ridge. Older rocks are farther away,
newer rocks closer.
Theory of Plate Tectonics
This theory states the lithosphere is
broken into rigid blocks called plates.
Ocean plates are thinner than
continental plates.
Plate Boundaries
Where plates meet.
Divergent boundary- where plates are
pulled apart. This forms rifts such as
the Great Rift Valley in E. Africa.
Continued
Convergent- Where plates collide. If
two continental plates collide mountains
form (Himalayas).
If an ocean and land plate collide, the
ocean plate is subducted (slides under
the land) to form a trench. If two
ocean plates collide, you also get a
trench.
continued
Transform fault- plates move past one
another in the same direction at
different rates or opposite directions
(San Andreas).
Volcanoes
Strato-volcanoes: alternating flows of
lava and ash. Mt. St. Helens
Sheild volcanoes: sloping mountains
made from lava. Mauna Loa
Cinder-cone volcanoes: violent
eruptions that blow out lava as cinders.
Paricutin in Mexico
Historic Eruptions
1883: Krakatoa in Indonesia sent ash
all around the globe; sunsets were
strange colored for months.
1989: Wahaula Visitor Center in Hawaii
engulfed by lava
Advantages of Geologic Activity
Iceland: geothermal energy used to
heat homes and produce electricity
Basalt is a raw material used in cleaning
supplies
Volcanic glass is used for stone work
and has been used for arrowheads