Dating Techniques
1) Explain how reversals in the earths magnetic field help us date ocean sdeiments?
a. Earth resembles a giant bar magnet. Where the poles can change orientation. These poles have changed in the past where North has become South and vice versa. As these changes happen, iron particles in the sediments will align accordingly. From this change in orientation we can trace back the origins of the sediment.
2) What are the limitation of radio carbon dating? What is the half life? And significance to dat material?
a. HL = 5730 yrs.
b. Incorporated with plants via photosynthesis which is then introduced into the food chain when an animal consumes it.
c. Can only date organic substances or objects which were once organic (ie silk). The C-14 has to be introduced into the food chain via animal eating a plant or an animal eating another animal etc etc.
d. The concentration of C-14 in the atmosphere has to be known to use this method.
e. The current time limitations are about 40k-50k years. (Holocene and latter portions of the Pleistocene)
3) What is the age limit of this technique?
a. 40k-50k years
4) What are the relative percentages of the carbon isotopes
a. C-12 = 98.89%, C-13 = 1.11%, C-14 = 10^-14%
5) How is C-14 formed?
a. When cosmic rays bombard nitrogen in the upper atmosphere. If a ray hits an atomic nucleaus which then hits a nitrogen nucleus a proton will be released and the nitrogen formed into C-14
6) Has C-14 concentration been consistent
a. C-14 in the