Dinosaur Extinction: Geologic Time Scale

Geologic Time Scale

The numbers on the time scale refer to time in millions of years ago. At 65 million years ago, earth experienced the global mass extinction event that defines the boundary between the Cretaceous and Tertiary (abbreviated K and T) geological periods and, a broader scale, the boundary between the Mesozoic and Cenozoic eras.

The Deccan Traps volcanism, one of the greatest volcanic events in earth history, erupted 65 million years ago, at the time of the K-T extinctions. Flooding earth's surface with CO2, and causing climatic warming known as a greenhouse, and chemical changes in the ocean, the Deccan Traps volcanism triggered extinctions on the lands and in the oceans. The Deccan Traps volcanism is thus the primary physical event producing the boundary between the Mesozoic and Cenozoic eras.