Name: 
Information you need to complete this is in the Introduction
Please check with your GSI about what sections to complete.
The graph below shows the relationship between the daughterparent ratio at the time of the test and the number of half lives elapsed for a limited number of halflives.
Using this graph, you can determine the age of a few samples.
P_{t} 
D_{t} 
D_{t}/P_{t} 
Halflives elapsed 
Age (Gyr) 
12,569 
60,332 



840 
8400 



56 
1178 



Below are three isocrons for 3 different rocks using the RbSr method described in the introduction. For each of the three graphs below: State whether or not this is a valid or invalid method. If it is not a valid method, explain why. If it is a valid method, draw a bestfit line and write the equation of the line in the space beside the graph. Calculate the age of the rock from the slope of the line. The halflife of rubidium87 is 48.8 billion years.
The graphs below show the graph of age or argon40:argon39 vs argon39 for three samples.
Last modified: 2/19/08 by SAM with material/suggestions from EP