Students should be able to understand the principles and have that as a background so that age determinations by paleontologists and geologists don't seem like black magic. Geologists in the late 18th and early 19th century studied rock layers and the fossils in them to determine relative age.William Smith was one of the most important scientists from this time who helped to develop knowledge of the succession of different fossils by studying their distribution through the sequence of sedimentary rocks in southern England.For example, U-235 is an unstable isotope of uranium that has 92 protons and 143 neutrons in the nucl eus of each atom.
Return to top Each team of 3 to 5 students should discuss together how to determine the relative age of each of the rock units in the block diagram (Figure 1).
After students have decided how to establish the relative age of each rock unit, they should list them under the block, from most recent at the top of the list to oldest at the bottom.
It is estimated to require four hours of class time, including approximately one hour total of occasional instruction and explanation from the teacher and two hours of group (team) and individual activities by the students, plus one hour of discussion among students within the working groups.
Explore this link for additional information on the topics covered in this lesson: This activity will help students to have a better understanding of the basic principles used to determine the age of rocks and fossils. Objectives of this activity are: 1) To have students determine relative age of a geologically complex area.
The teacher should tell the students that there are two basic principles used by geologists to determine the sequence of ages of rocks.
They are: Principle of superposition: Younger sedimentary rocks are deposited on top of older sedimentary rocks.Where the amounts of parent and daughter isotopes can be accurately measured, the ratio can be used to determine how old the rock is, as shown in the following activities.Part 2a Activity At any moment there is a small chance that each of the nuclei of U-235 will suddenly decay.2) To familiarize students with the concept of half-life in radioactive decay.3) To have students see that individual runs of statistical processes are less predictable than the average of many runs (or that runs with relatively small numbers involved are less dependable than runs with many numbers). Students not only want to know how old a fossil is, but they want to know how that age was determined.