Keyah Math > Activities > Ages of Rocks and the Earth

# Ages of Rocks and the Earth

#### Summary

This activity introduces students to the mathematics of radiometric dating. Students first apply the rubidium-strontium isotopic system to date rock samples from the San Juan Mountains of southwest Colorado, and then to date a meteorite and estimate the absolute age of the Earth.

Click here to view the full activity on the Kéyah Math Project website.

## Learning Goals

Objectives
• Review the use of radioactive decay as a "natural clock" for dating rocks.
• Apply the decay equation for the rubidium-strontium isotope system to obtain ages for rock samples from the San Juan Mountains in southwest Colorado.
• Apply this equation to data from a meteorite to estimate the age of the Earth.

Mathematical Skills
• Use basic algebra.
• Solve exponential equations.
• Use logarithms.
• ## Context for Use

This activity consists of a set of quantitative problem-solving exercises that can be used as an in-class activity or an assignment in any introductory geology, geography, Earth science, or Earth materials course.

## Teaching Notes and Tips

An Instructor's Guide to all Kéyah Math activities is available online from the Instructor Resources page on the Kéyah Math website.

## Assessment

Students record their work and answers in a word-processor document or a notebook, which can be submitted to the instructor for assessment. Solutions to these problems are available online from the Instructor Resources page on the Kéyah Math website.

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