Geology. A set of successive deposits or formations having some common fossil or mineral features; an assemblage of successive, usually…

Geology. Originally: a major stratigraphic division. Now: spec. that corresponding to a geological period (period, n. 6) and further divided into…

Geology. (Usually spelt terrane.) A name for a connected series, group, or system of rocks or formations; a stratigraphical subdivision.

Geology. (Variously used: see quots. 1881 1910.) In modern use, a division of a stratigraphic series, composed of a number of zones and corresponding…

Geology. In the classification of rocks and fossils. A stratigraphic unit consisting of two or more formations.

A part separated or divided off from the remainder; one of the portions into which a thing is cut or divided. Geology. (See quot. 1882.)

Archaeology. A level at which a particular group of remains is found, or which is taken as representing a particular culture or cultural period.

see quot. 1932.

Geology. A group of strata whose order represents a single chronological sequence.

a stratigraphic zone consisting of all the strata that are characterized by the presence of a particular fossil species or other distinctive…