## Radiometric & Relative Ages geog1 zsr

Provide accurate answers to all of the following questions.

1. A rock is going to be analyzed for its radioactive isotope contents, X and Y. X is the parent and Y is the daughter isotope. Assume that the half-life of the radioactive isotopes is 5,730 years. Based on this information, answer the following two questions.

A) How much of the parent (X) and how much of the daughter (Y) were present at the time the rock formed? Choose one of the following (3 points) and explain why (3 points). Total: 6 points.

A) X = 100 % ; Y = 100 %

B) X = 100 % ; Y = 0 %

C) X = 0 % ; Y = 100 %

D) X = 50 % ; Y = 50 %

B) How much of the parent (X) and how much of the daughter (Y) will be present after two half-lives? Choose one of the following (3 points) and explain why (4 points). Total: 7 points.

A) X = 25 % ; Y = 75 %

B) X = 50 % ; Y = 50 %

C) X = 75 % ; Y = 25 %

D) X = 12.5 % ; Y = 87.5%

2. The diagram below is a cross section of a hypothetical area. Place the lettered features (A through P) in the proper sequence, from oldest to youngest (left: oldest; right: youngest). (12 points)

Hint: “C” is the youngest rock because it cuts across all other rocks; “P” is the oldest because it is underneath all other rocks.

Note: You don’t need to write the reason as I did above, this was meant to explain to you the reason why “C” is the youngest and “P” is the oldest.