The Collaborative International Dictionary
Cretacic
Cretacic \Cre*tac"ic\
Cretaceous acid, 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. See Cretaceous.