a. 白垩系的, 白垩纪的

n. 白垩纪, 白垩系

[医] 白垩的

Cretaceous \Cre*ta"ceous\ (kr[-e]*t[=a]"sh[u^]s), a. [L.
cretaceus, fr. creta chalk. See {Crayon}.]
1. Having the qualities of chalk; abounding with chalk;
chalky; as, cretaceous rocks and formations. See {Chalk}.

2. (Geol.) Of, pertaining to, or designating, the period of
time following the Jurassic and preceding the Tertiary,
generally given as from 144 million years b. p. to 65
million years b. p.. Also called