Geological Dating (323 – 333)
_____________ – The approximate age of a rock layer or fossil
determined by the age of the layers or fossils above or beneath.
______________ – A layer of sedimentary rock is older than the layer
above it
Exceptions:
1)
2)
3)
4)
________________ - This is the actual age of a substance.
This is measured by using the half life of radioactive elements.
Radioactive elements - These are _____________ (varieties of certain
elements containing different masses) of elements whose nucleus is
decaying (breaking down, releasing energy and particles at a
_____________rate).
EX. Uranium 238 Carbon 14
- The number stands for the mass of the isotope
- Uranium decays until it reaches lead 206. When an element stops
decaying it is considered stable.
Half Life - This is the time it takes half the mass of a radioactive isotope to
decay into its stable form.
Uranium 238:
Carbon 14: