Determine The Age Of Rocks & Fossils

Fossils are dated using knowledge of evolution and the ages of rocks around them

There is no easy way to date a rock or fossil. Scientists use different methods that allow them to make an educated guess as to the age of the rocks and fossils they find. The most common methods are radiometric dating and stratigraphic dating. Radiometric dating uses the known rate of decay of radioactive materials found in rocks and minerals to discover when they were created. Stratigraphic dating uses the Earth’s layers, laid down over time, and the known succession of plant and animal life to determine the age of rocks and fossils.

Instructions

Date Rocks And Fossils

1. Determine what kind of rock or mineral you have. Different rocks and minerals contain different radioactive elements. Rates of decay and methods of testing will vary depending on the rock’s radioactive elements, so it is important to be certain of the type of rock or mineral you want to date.

2. Find out if the rock or mineral you’ve found has already been dated. Since many rocks and minerals have already been dated and a geologic picture of the Earth has already been created, it is possible the one you have already has a place in the geologic chronology. Study books about the area where you found your rock or mineral or visit your local university’s geology department for help with identification and dating.

3. Determine what kind of fossil you have. Fossils are the imprints left behind by dead plants and animals. Scientists know that plants and animals evolve and change over time and that when one form of a plant or animal dies another one typically (but not always) takes its place. Using this knowledge, combined with the knowledge already gained through radiometric dating of the rocks and minerals in which fossils are found, you can get a good idea of when a fossilized animal lived.

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