The Collaborative International Dictionary of English v.0.48:
[Webster 1913 Suppl. +PJC]
an old name for carbonic acid.
Cretaceous formation (Geol.), the series of strata of
various kinds, including beds of chalk, green sand, etc.,
formed in the Cretaceous period; -- called also the chalk
formation. See the Diagram under Geology.
Cretaceous period (Geol.), the time in the latter part of
the Mesozoic age during which the Cretaceous formation was
deposited, and at the end of which the dinosaurs died out.
[1913 Webster +PJC]