The major lithostratigraphic unit next higher in rank than a formation; a group consists of two or more associated and adjoining formations having significant lithologic features in common.

A grouping of formations used in stratigraphy.

An association of people united by a common interest. Each group can have any number of Parent Groups and any number of Child Groups

rock] The formal lithostratigraphic unit next in rank above formation. A group includes two or more contiguous or associated formations with significant lithogic features in common. The type or reference sections of a group re those of its component formations.

In geologic mapping, a unit that consists of two or more formations.