What is "corniferous"

Corniferous \Cor*nif"er*ous\ (k?r-n?f"?r-?s), a. [L. cornu horn + -ferous.] (Geol.) Of or pertaining to the lowest period of the Devonian age. (See the Diagram, under Geology.) The Corniferous period has been so called from the numerous seams of hornstone which characterize the later part of the period, as developed in the State of New York.