Relative dating practice
*Life Science: Fossils indicate that many organisms that lived long ago are extinct.
Extinction of species is common; most of the species that have lived on the earth no longer exist.
INTRODUCTION Scientists have good evidence that the earth is very old, approximately four and one-half billion years old.
Scientific measurements such as radiometric dating use the natural radioactivity of certain elements found in rocks to help determine their age.
The study of fossils and the exploration of what they tell scientists about past climates and environments on Earth can be an interesting study for students of all ages.
This also means that fossils found in the lowest levels in a sequence of layered rocks represent the oldest record of life there.
By matching partial sequences, the truly oldest layers with fossils can be worked out.
By correlating fossils from various parts of the world, scientists are able to give relative ages to particular strata. Relative dating tells scientists if a rock layer is "older" or "younger" than another.
Sequencing the rock layers will show students how paleontologists use fossils to give relative dates to rock strata.
Once students begin to grasp "relative" dating, they can extend their knowledge of geologic time by exploring radiometric dating and developing a timeline of Earth's history.