Lias
1. The earliest of the Jurassic epochs, followed by the Dogger. The Lias is dated at 208–178 Ma ( Harland et al., 1989), and comprises the Hettangian, Sinemurian, Pliensbachian, and Toarcian Ages.

2. The corresponding European series, roughly contemporaneous with most of the Herangi (New Zealand). Blue-grey shales and muddy limestones are typical of the Lias, with Dactylioceras and Gryphaea among the more important fossils found in the extensive outcrops of England and France.

Lias A commonly used term for the lowest stage of the Jurassic. The Liassic is synonymous with the Hettangian/Sinemurian Stages of Europe. Blue-grey shales and muddy limestones are typical of the Lias, with extensive outcrops in England and France.

Lias A name commonly given to the lowest stage of the Jurassic, with extensive outcrops of blue-grey shales and muddy limestones in Britain and France in which many fossils have been found.

lias blue limestone rock XVII lyas (geol.) strata forming the lowest division of the Jurassic XIX. — F. liais, of unkn. orig.