Beryllium dating method
For similar reasons the ratio of deuterium to hydrogen acts the same way. This process also depends on the relative temperatures of different years, which allows comparison with paleoclimatic data. Thus, each annual layer starts 18O rich, becomes 18O poor, and ends up 18O rich. This depletion is a temperature dependent process so in winter the precipitation is more enriched in H2(16O) than is the case in the summer.The Earth's magnetic field then traps them, with only a slight "leakage" of the isotopes to the lower atmosphere.The amount of "leakage" depends on the height of the ionosophere, which changes primarily in response to the Solar cycle, with periods of maximum solar activity corresponding to the highest extent of the ionosphere. The basis of this method lies with looking for items that vary with the seasons in a consistent manner. References Of the four distinct methods for determining the ages of ice cores, the first three are direct experimental tests and the fourth rests on somewhat uncertain theories.
Of the temperature dependent markers the most important is the ratio of 18O to 16O.
Radiocarbon dating, also known as carbon-14 dating, is a radioactive decay-based method for determining the age of organic remains that lived within the past 50,000 years.
Most carbon-14 is created from nitrogen-14 in the earth’s upper atmosphere as a consequence of cosmic ray bombardment.
Thus each annual layer starts 10Be and 36Cl poor, becomes 10Be and 36Cl rich, and then becomes poor again. Although what is said above is true, this is an exceedingly minor effect.
9Be and 35Cl) one can determine the season of the year the precipitation occurred.