# Absolute age dating activity group

### Earth Floor: Geologic Time

But these two methods only give the relative age of rocks--which are younger and which are older. Image showing the radioactive age dating of a rock. Please. In this activity, students gain a better understanding of radioactive dating and half -lives. Students Each group begins with M&Ms in a container. by reviewing the 2 broad ways scientists age rocks (relative dating and radioactive dating). dating to accurately determine the age of objects and how relative dating . Object Cards and Unknown Fossil copies for each group (Blackline.

The age of a rock in years is called its absolute age.

## Relative Age Dating Activity.

Geologists find absolute ages by measuring the amount of certain radioactive elements in the rock. When rocks are formed, small amounts of radioactive elements usually get included. As time passes, the "parent" radioactive elements change at a regular rate into non-radioactive "daughter" elements.

Thus, the older a rock is, the larger the number of daughter elements and the smaller the number of parent elements are found in the rock.

A common "parent-daughter" combination that geologists use is radioactive uranium and non-radioactive lead. As shown in the diagram above, uranium is trapped in a newly formed rock.

As the rock ages, more and more of the uranium changes into lead. The age of the rock in years can be found by measuring the rate at which a parent element decays and then measuring the ratio of parent element to daughter element in the rock. The ages in years of the different geological time periods are found by measuring the absolute ages of many rocks from all of the different periods.

The absolute ages of some of the different geologic time periods are shown along the right side of the Staircase of Time.

### Age Dating, Educational Resources for K

The steps of the Staircase of Time are drawn to be almost the same size, so you might think that the time periods are the same length, but they are not. Chris Stassen, Talk Origins Archive. Offers scientific explanations of isochron radiometric dating some technicalequations, graphs, descriptions of methods, discussions of potential problems and methods scientists take to ensure reproducible results and avoid sample contamination. Changing Views of the History of the Earth.

Richard Harter, Talk Origins Archive. Summary of the history of human perception of geologic time from Genesis in the Bible to modern scientific interpretations.

Includes a chronology of significant writings from to Age of the Earth. Offers scientific explanations and rebuttals to common criticisms of radiometric dating by non-scientists Foundational methods--Dating methods.

National Museum Smithsonian Institution. Provides brief overview of 1 relative dating and stratigraphic methods, 2 absolute dating and radiometric dating, including a table with parent to daughter isotopes and half lives of those isotopes commonly used in radiometric dating, 3 paleomagnetics and 4 geologic time.

Pamela Gore, Georgia Perimeter College.

Short discussion of radioactive dating and stratigraphic principles. Includes tables of common radioactive parent isotopes and their stable daughter products, and half lives of common radioactive isotopes.

- Radioactive Dating: Looking at Half-Lives Using M&Ms

Geologic timeU. This online version of their informative booklet contains short, content explanations about relative time, major geologic time divisions, index fossils for use in age dating, radiometric dating and the age of the earth.