Definition of Lias in English:

Lias

noun

Geology
  • 1The earliest epoch of the Jurassic period, lasting from about 208 to 178 million years ago.

    1. 1.1The system of rocks deposited during the Lias epoch, consisting of shales and limestones rich in fossils.

Origin

Late Middle English (denoting blue lias): from Old French liais hard limestone probably from lie (see lees).

Pronunciation:

Lias

/ˈlīəs/