In geology, a group is a lithostratigraphic unit consisting of a series of related formations that have been classified together to form a group. Formations are the fundamental unit of stratigraphy. Groups may sometimes be combined into supergroups .
5-547: The Sumner Group is a sedimentary geologic group of Lower Permian age. It is defined in east-central Kansas and extends into Oklahoma and Nebraska as well as the Colorado subsurface where it is undivided. This article about a specific stratigraphic formation in Kansas is a stub . You can help Misplaced Pages by expanding it . This article related to the Permian period
10-421: Is a stub . You can help Misplaced Pages by expanding it . Group (geology) Groups are useful for showing relationships between formations, and they are also useful for small-scale mapping or for studying the stratigraphy of large regions. Geologists exploring a new area have sometimes defined groups when they believe the strata within the groups can be divided into formations during subsequent investigations of
15-695: The area. It is possible for only some of the strata making up a group to be divided into formations. An example of a group is the Glen Canyon Group , which includes (in ascending order) the Wingate Sandstone , the Moenave Formation , the Kayenta Formation , and the Navajo Sandstone . Each of the formations can be distinguished from its neighbor by its lithology , but all were deposited in
20-531: The past also been used as units for chronostratigraphy and geochronology . These are the Rotliegend and Zechstein (both of Permian age); Buntsandstein , Muschelkalk , and Keuper ( Triassic in age); Lias , Dogger , and Malm ( Jurassic in age) groups. Because of the confusion this causes, the official geologic timescale of the ICS does not contain any of these names. As with other lithostratigraphic ranks,
25-612: The same vast erg . Not all these formations are present in all areas where the Glen Canyon Group is present. Another example of a group is the Vadito Group of northern New Mexico . Although many of its strata have been divided into formations, such as the Glenwoody Formation , other strata (particularly in the lower part of the group) remain undivided into formations. Some well known groups of northwestern Europe have in
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