Radioactive dating worksheet answer key


The idea behind radiocarbon dating is straightforward, but years of work were required to develop the technique to the point where accurate dates could be obtained. Research has been ongoing since the 1960s to determine what the proportion of 14
C in the atmosphere has been over the past fifty thousand years. The resulting data, in the form of a calibration curve, is now used to convert a given measurement of radiocarbon in a sample into an estimate of the sample's calendar age. Other corrections must be made to account for the proportion of 14
C in different types of organisms (fractionation), and the varying levels of 14
C throughout the biosphere (reservoir effects). Additional complications come from the burning of fossil fuels such as coal and oil, and from the above-ground nuclear tests done in the 1950s and 1960s. Because the time it takes to convert biological materials to fossil fuels is substantially longer than the time it takes for its 14
C to decay below detectable levels, fossil fuels contain almost no 14
C , and as a result there was a noticeable drop in the proportion of 14
C in the atmosphere beginning in the late 19th century. Conversely, nuclear testing increased the amount of 14
C in the atmosphere, which attained a maximum in 1963 of almost twice what it had been before the testing began.

Since sunlight causes the formation of C-14 in the atmosphere, and normal radioactive decay takes it out, there must be a point where the formation rate and the decay rate equalizes. This is called the point of equilibrium. To illustrate: If you were trying to fill a barrel with water but there were holes drilled up the side of the barrel, as you filled the barrel it would begin leaking out the holes. At some point you would be putting it in and it would be leaking out at the same rate. You will not be able to fill the barrel past this point of equilibrium. In the same way the C-14 is being formed and decaying simultaneously. A freshly created earth would require about 30,000 years for the amount of C-14 in the atmosphere to reach this point of equilibrium because it would leak out as it is being filled. Tests indicate that the earth has still not reached equilibrium. There is more C-14 in the atmosphere now than there was 40 years ago. This would prove the earth is not yet 30,000 years old! This also means that plants and animals that lived in the past had less C-14 in them than do plants and animals today. Just this one fact totally upsets data obtained by C-14 dating.


Radioactive dating worksheet answer key

Radioactive dating worksheet answer key



like-and-post.info