白垩统
白垩系

Cretacic \Cre*tac"ic\
[Webster 1913 Suppl. +PJC]

{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}.
[1913 Webster +PJC]