[trahy-as-ik] 
Geology| 1. | noting or pertaining to a period of the Mesozoic Era, occurring from 230 to 190 million years ago and characterized by the advent of dinosaurs and coniferous forests. |
| 2. | Also, Tri⋅as [trahy-uh s] the Triassic Period or System. |
| Tri·as·sic (trī-ās'ĭk) adj. Of or belonging to the geologic time, system of rocks, or sedimentary deposits of the first period of the Mesozoic Era, characterized by the diversification of land life, the rise of dinosaurs, and the appearance of the earliest mammals. See Table at geologic time. n. The Triassic Period or its system of deposits. [Late Latin trias, triad (from the subdivision of this period into three parts); see triad + -ic.] |