global updating - Scientific definition of relative dating

Locally, physical characteristics of rocks can be compared and correlated.

On a larger scale, even between continents, fossil evidence can help in correlating rock layers.

scientific definition of relative dating-56

This means that a quartz sandstone deposited 500 million years ago will look very similar to a quartz sandstone deposited 50 years ago.

Making this processes even more difficult is the fact that due to plate tectonics some rock layers have been uplifted into mountains and eroded while others have subsided to form basins and be buried by younger sediments.

*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.

These major concepts are part of the Denver Earth Science Project's "Paleontology and Dinosaurs" module written for students in grades 7-10.

The module is an integrated unit which addresses the following National Science Education Standards: *Science as Inquiry: Students develop the abilities necessary to do scientific inquiry — identify questions, design and conduct scientific investigations, use appropriate tools and technologies to gather, analyze and interpret data, think critically and logically to make the relationships between evidence and explanations, communicate results, and use mathematics in all aspects of scientific inquiry.

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.

*Earth and Space Science: Fossils provide important evidence of how life and environmental conditions have changed.

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