Member

A named subdivision of a formation with its own lithological character — the Fossil Butte Member of the Green River Formation, the Fox Hills Member of the Pierre Shale. Not every formation is divided into members.

Sources

International Commission on Stratigraphy — International Stratigraphic Guide (abridged)
North American Commission on Stratigraphic Nomenclature — North American Stratigraphic Code (2005)

Cite this article

Stratum Study. "Member" (Glossary). Stratum Study pack 2026.09, as of 2026-09-16. https://stratum.black/study/glossary/member. Accessed 2026-09-20.

BibTeX · CSL-JSON

@misc{stratum-member,
  title        = {Member},
  author       = {{Stratum Study}},
  howpublished = {\url{https://stratum.black/study/glossary/member}},
  year         = {2026},
  note         = {Glossary article, Stratum Study pack 2026.09, as of 2026-09-16; sources: stratum. Accessed 2026-09-20.}
}

Citations carry the pack version and the article's as-of date so they resolve to the same text later. The facts themselves belong to the sources listed below; cite those for the science.