Formation · Cambrian
Marjum Formation
Miaolingian unit, Utah
The Marjum Formation overlies the Wheeler Shale in Utah's House Range and yields a slightly younger trilobite fauna dominated by Modocia, Olenoides and agnostids, plus rare soft-bodied animals and the sponge-rich beds of Marjum Pass. It is less commercially exploited than the Wheeler, so specimens are scarcer and more expensive, and the same enhancement warnings apply.
| Country | United States |
|---|---|
| Region | Utah |
| Age | Drumian, Miaolingian |
| Age range | ~502–497 Ma |
| Macrostrat rank | Fm· Macrostrat |
| Macrostrat age | 502–502 Ma· Macrostrat |
| Lithology | limestone, shale· Macrostrat |
| Environment | inferred marine· Macrostrat |
| Macrostrat columns | 1 column(s) sampled from 1 unit(s)· Macrostrat |
| PBDB collections | 36 collections, 282 occurrences· Paleobiology Database |
Collecting and legality
House Range BLM land: casual collecting of invertebrates for personal use is allowed, sale is not; commercial material comes from private claims. The Marjum soft-bodied sites are the subject of active research, so treat rare arthropods with care.
Lithology and setting
Thin-bedded lime mudstones and shales above the Wheeler Shale, deposited in the deep House Range Embayment.
Commonly recorded taxa (PBDB)
Genera most often recorded from this unit in the Paleobiology Database (first 200 occurrences): Diagoniella (13), Modocia (11), Choia (10), Bolaspidella (7), Hamptonia (6), Olenoides (6), Hintzespongia (5), Ptychagnostus (5), Acidusus (4), Leptomitella (4), Narynella (4), Protospongia (4), Tuzoia (4), Valospongia (4), Branchiocaris (3).
Source: Paleobiology Database
Collecting rules
Elsewhere
- Macrostrat: 1224
- macrostratConcept: 9186
- PBDB: strata:Marjum
- Wikidata: Q6766370
- Macrostrat stratigraphic name
- PBDB occurrences for this unit
- Wikipedia: Marjum Formation
- Mindat: Marjum Formation
Cite this article
Stratum Study. "Marjum Formation" (Formation). Stratum Study pack 2026.09, as of 2026-09-19. https://stratum.black/study/formations/marjum-formation. Accessed 2026-09-20.
@misc{stratum-marjum-formation,
title = {Marjum Formation},
author = {{Stratum Study}},
howpublished = {\url{https://stratum.black/study/formations/marjum-formation}},
year = {2026},
note = {Formation article, Stratum Study pack 2026.09, as of 2026-09-19; sources: stratum, macrostrat, pbdb, wikidata, commons. 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.