Dating of fossils and rocks
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.
The atoms in some chemical elements have different forms, called isotopes.
Then, count the number of pieces of candy left with the M facing down.
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.
The same rock formation also contains a type of trilobite that was known to live to million years ago.Scientists can check their accuracy by using different isotopes.The first radiometric dates, generated aboutshowed that the Earth was hundreds of millions, or billions, of years old.These are the parent isotope that did not change during the first half life.The teacher should have each team report how many pieces of parent isotope remain, and the first row of the decay table Figure 2 should be filled in and the average number calculated.