Eonothem

eonothem

[′ēn·ə‚them]
(geology)
A chronostratigraphic unit, above erathem, composed of rocks formed during an eon of geologic time.

Eonothem

 

(geology), the largest subdivision of the general stratigraphic scale, corresponding to a long stage in the development of the earth and its organic world. An example is the Phanerozoic eonothem, which includes three erathems (groups), consisting of 12 stratigraphic systems. (SeeSTRATIGRAPHY.)