Isochron Diagrams
Page 14 of 17

Isotope

Slope

Age

0.00 HL

On the control part of the graph select the Rb/Sr option.

Rember that the Half-life of Rb-87 is 48.8 Billion Years. Note that the scale on the horizontal axis is now 10 times greater than the vertical axis.

Move the slider and watch the slope of the isochron change over time.

You can also type numbers directly into the text box displaying the slope. Press the return key to activate any typed-in change.

Go ahead and complete the table.

Isochron Slope Age in MILLION of years Geologic Event
0.002
1.
Dinosaurs roamed the earth
0.0077
2.
First evidence of abundant fossils
0.0362
3.
Proterozoic Era begins
0.0582
4.
Oldest radiometrically dated Earth rock
0.0668
5.
Earth's age, inferred from meteorites

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