Dating of fossils and rocks rules about dating a minor
This uses radioactive minerals that occur in rocks and fossils almost like a geological clock.
So, often layers of volcanic rocks above and below the layers containing fossils can be dated to provide a date range for the fossil containing rocks.
After the graphs are plotted, the teacher should guide the class into thinking about: Is it the single group's results, or is it the line based on the class average? Unless the rock is heated to a very high temperature, both the U and its daughter Pb remain in the rock.
A geologist can compare the proportion of U atoms to Pb produced from it and determine the age of the rock.
This can often be complicated by the fact that geological forces can cause faulting and tilting of rocks.
Studying the layers of rock or strata can also be useful. If a layer of rock containing the fossil is higher up in the sequence that another layer, you know that layer must be younger in age.
The task now for each team is to determine how many timed intervals that is, how many half-lives the set of pieces they are looking at has experienced. Both the team that turned over a set of pieces and the second team that examined the set should determine how many million years are represented by the proportion of U and Pb present, compare notes, and haggle about any differences that they got.
The methods are all based on radioactive decay: Fossils may be dated by calculating the rate of decay of certain elements.
Since then, geologists have made many tens of thousands of radiometric age determinations, and they have refined the earlier estimates.
Age estimates can be cross-tested by using different isotope pairs.