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

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! Lithosphere- crust and upper most part of mantle- tectonic plates move Asthensophere- below 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 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

Pull Apart Divergent Boundary- two plates pull apart Forms Mid-Ocean Ridges Mid-Atlantic Ridge- Iceland 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