Name: ______Period: _____ Date:______

Absolute & Relative Dating

Use your knowledge of relative dating to help you determine the sequence of events below.

1.)  ______2.) ______3.) ______4.) ______5.) ______6.) ______7.) ______

8.)  ______9.) ______10.) ______11.) ______12.) ______13.) ______

Assume R is an extrusion dated to be 90 million years old and T is dated to be 60 million years old.

1.) Estimate an age for rock layer J. ______

2.) Estimate an age for rock layer W. ______

3.) Estimate an age for rock layer B. ______

Assume M is an extrusion dated to be 130 million years old.

4.) Estimate an age for rock layer K. ______

5.) Estimate an age for rock layer L. ______

6.) Estimate an age for rock layer P. ______

7.) Estimate an age for fault A. ______

Use the table, graph, and geologic cross-section below to assist you in answering the following geologic dating practice questions.

Parent Isotope / Half-Life / Daughter
Uranium-235 / 704 million yrs / Lead-207
Potassium-40 / 1,250 million yrs / Argon-40

Determine the sequence of events in the

formation of the geologic cross-section above

and record it in the relative age listed below.

Use the radiometric dating to determine the ages Intrusion I

of the igneous intrusions and extrusions, then A radiometric dating lab finds 600 uranium-235 atoms

estimate the ages of the surrounding rock and 1800 lead-207 atoms in a rock sample. How old

based on these calculations. would they date intrusion I to be?

Relative Age Estimated Age

1.) ______

2.) ______

3.) ______Intrusion J

4.) ______Intrusion J is dated using potassium-argon dating.

5.) ______800 potasium-40 atoms are measured compared to

6.) ______800 argon-40 atoms. How old would Intrusion J

7.) ______be dated?

8.) ______

9.) ______

10.) ______