ISOTOPIC DATING QUESTIONS

Answer these questions on a separate piece of paper. Restate the questions in your answers.

1. Astronomers think that the Earth probably formed at the same time as all the other rocky materials in or solar system, including the oldest meteorites. The oldest meteorites ever found on earth contain nearly equal amounts of both uranium-238 and lead-206. Based on your note son isotopic dating, what is the presumed age of the earth?

2. The carbon in a buried peat bed has only about 6% of the C-14 of modern shells. If you assume the global inventory of radiocarbon has remained constant, then what is the age of the peat bed?

3. Layers of sand on New Jersey and California beaches contain zircon crystals (which is a good source of U-238 and Pb-206).

a. Could the zircon crystals be used to date exactly when the layers of sand were deposited?

b. Suggest a rule that geologists should follow when they date rocks according to radiometric ages of crystals inside them.