Carbon Dating
• Used for determining the age of earth
materials
• Age of rocks, fossils
• Every living organism on Earth has carbon
• When organism dies, carbon remains but
begins to break down at a predictable ratehalf life
• Half-life of carbon-14 is 5,730 years
How old is it?
• Every 5,730 years the amount of carbon will
reduce by half.
• This means that no matter how old something
is, the amount of carbon can get smaller and
smaller but never go away.
• If a fossil of a fish is found and scientists know
it originally had 2g of carbon-14 and now only
has 0.0625g, how old is it?
• If carbon is in all living things, it is in rocks and
soil- decomposition.
• Carbon dating is used to help estimate the age
of the earth
• But the oldest rocks are usually located at the
bottom of a rock profile. Why?
Law of Superposition
• Sediments or lava are
deposited on top of the
existing rocks or soil.
• Those sediments are
compacted to form new
rock
• New rock on top, old
rock at bottom
Exceptions to the Law of Superposition
• Faulting
• Non-deposition
• Intrusion- injection of
lava from the mantle
• Which layer is the
oldest?
• Which is the youngest?
Layers of the Earth
• inner core - mass of solid
iron with a temperature
of 70000 F
• outer core – liquid iron,
responsible for our
magnetic fields
• mantle - slow moving
molten rock or magma,
20000 F
• crust - layer from 4-25
miles thick consisting of
sand and rock
But wait, There’s more!
• Lithospherecrust and upper
most part of
mantle- tectonic
plates move
• Asthensopherebelow
lithosphere,
upper part of
mantle
Focus on the Mantle
• Liquid rock
• Heated by the core
• Heat creates convection
currents
• Convection
currents make
tectonic plates
move
Mantle moves, Plates move
Continental vs. Oceanic Plates
• Continental crust is less dense than oceanic
crust
• When continental plate collides with oceanic
plate, oceanic will go under the continental
and oceanic plate is subducted or recycled
back into the mantle.
• ***See Plate Boundaries handout ***
When Plates Collide
• Convergent Boundarytwo continental plates
collide forming
mountains- Mt. Everest
and Himalayan Mts
• Subduction Zoneoceanic vs. continental
or oceanic vs. oceanicRing of Fire, Mt. St.
Helens, Mt. Vesuvius
Pull Apart
• Divergent Boundarytwo plates pull apart
• Forms Mid-Ocean
Ridges
Mid-Atlantic RidgeIceland Volcano
Sliding Past Each Other
• Transform Boundary
↑↓- Creates Faults
• Faults- cracks in the
Earth where plates
move past each other
• San Andreas Fault, New
Madrid Fault
• EARTHQUAKES!
Earthquake!
• Fault- plate boundary
• Focus- point inside the
earth where earthquake
begins
• Epicenter- Point on
SURFACE where
earthquake begins
Earthquakes Release Energy
• P-Wave- Primary Wave
• S-Wave- Secondary
Wave
• Surface wave
• Waves are longitudinal
or transverse
Long Term Effects of Plate Movement
• Continental drift
• Slow and gradual
movement of tectonic
plates in the same
direction
• Alfred Wegener
• Pangaea
• Caused by convection
currents in mantle
Day Night and More
• Rotation- spinning of
Earth on axis
• Revolution- orbit of
Earth around the Sun
• Earth’s axis is tilted 23.5
degrees
• Altitude, longitude and
latitude
• Day and Night
• Year
• Seasons
• Determines the temp
and climate of a region