In this interactive tutorial you will explore how geologists use clues in rocks to determine the order in which rocks formed. Learn how principles of radioactivity are used to assign actual ages to rocks. Students will explore fossils...

[Free Registration/Login may be required to access all resource tools.] Covers the Mesozoic Era, the age of dinosaurs.

An overview of Walter and Luis Alverez's theory that a large meteorite crashed into earth causing huge tidal waves, showers of ash, and an enormous dust cloud.