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Page 1: Carbon Dating

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 rate- half life

• Half-life of carbon-14 is 5,730 years

Page 2: Carbon Dating

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?

Page 3: Carbon Dating

• 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?

Page 4: Carbon Dating

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

Page 5: Carbon Dating

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?

Page 6: Carbon Dating

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

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Page 8: Carbon Dating

But wait, There’s more!

• Lithosphere- crust and upper most part of mantle- tectonic plates move

• Asthensophere- below lithosphere, upper part of mantle

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Focus on the Mantle• Liquid rock• Heated by the core• Heat creates convection

currents• Convection currents make tectonic plates move

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Mantle moves, Plates move

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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 ***

Page 12: Carbon Dating

When Plates Collide

• Convergent Boundary- two continental plates collide forming mountains- Mt. Everest and Himalayan Mts

• Subduction Zone- oceanic vs. continental or oceanic vs. oceanic- Ring of Fire, Mt. St. Helens, Mt. Vesuvius

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Pull Apart

• Divergent Boundary- two plates pull apart

• Forms Mid-Ocean RidgesMid-Atlantic Ridge- Iceland Volcano

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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!

Page 15: Carbon Dating

Earthquake!

• Fault- plate boundary• Focus- point inside the

earth where earthquake begins

• Epicenter- Point on SURFACE where earthquake begins

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Earthquakes Release Energy

• P-Wave- Primary Wave• S-Wave- Secondary

Wave • Surface wave

• Waves are longitudinal or transverse

Page 17: Carbon Dating

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

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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


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