The Triassic is a geologic period and system that extends from about 250 to 200 Ma . It is the first period of the Mesozoic Era, and lies between the Permian and Jurassic periods. Both the start and end of the period are marked by major extinction events. The Triassic was named in 1834 by Friedrich von Alberti, after the three distinct rock layers that are found throughout Germany and northwestern Europe—red beds, capped by chalk, followed by black shales—called the "Trias."

The above text is a snippet from Wikipedia: Triassic
and as such is available under the Creative Commons Attribution/Share-Alike License.

Need help with a clue?
Try your search in the crossword dictionary!