Llangynog Inlier

Llangynog Inlier (Coomb Volcanic Formation)
Stratigraphic range: Ediacaran 566–563  Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓ [1]
Type	Formation
Unit of	Wrekin terrane
Sub-units	Castell Cogan Rhyolite and Coed Cochion Volcaniclastic Member
Thickness	1100 m (3,608 ft)
Lithology
Primary	Volcaniclastic Rocks [1]
Other	Rhyolite, Dolerite, Dacite, Rhyolitic Conglomerate [1]
Location
Country	Wales

The Llangynog Inlier (Coomb Volcanic Formation) is a geologic formation that crops out in Wales, which mainly consists of volcaniclastic rocks and rhyolite, as well as dolerite, dacite and a layer of rhyolitic conglomerates. A recent study also managed to date the Inlier to between 566 and 563 Ma, which means it temporally correlates directly with the Fermeuse Formation of Newfoundland, the Beacon Hill Formation in the Charnwood Forest, and the neighboring Stretton Shale Formation in Long Mynd. It also preserves fossils dating back to the Ediacaran period.

Paleobiota

The Llangynog Inlier is that of a tidally active shallow marine environment that saw much volcanic activity. It also preserves a small collection of Ediacaran forms, from the discoidal Aspidella to the elongated Palaeopascichnus. ^[1]

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

incertae sedis

Genus	Species	Notes	Images
Aspidella [1]	Aspidella sp.	Enigmatic discoidal fossil.
Ediacaria [2]	Ediacaria sp.	Enigmatic discoidal fossil, possibly a synonym of Aspidella.
Hiemalora [1]	Hiemalora sp.	Discoid organism, possibly holdfasts of petalonamids.
Palaeopascichnus [1]	Palaeopascichnus sp.	Palaeopascichnid organism.

Ichnogenera

Genus	Species	Notes	Images
Sinusoidal trace [1]	???	A sinusoidal trace fossil, possibly a feeding trace of an unknown organism.

See also

• Earth sciences portal
• United Kingdom portal
• Paleontology portal

• List of fossiliferous stratigraphic units in the United Kingdom

References

1. Clarke, Anthony J. I.; Kirkland, Christopher L.; Menon, Latha R.; Condon, Daniel J.; Cope, John C. W.; Bevins, Richard E.; Glorie, Stijn (January 2024). "U–Pb zircon–rutile dating of the Llangynog Inlier, Wales: constraints on an Ediacaran shallow-marine fossil assemblage from East Avalonia". Journal of the Geological Society. 181 (1). doi:10.1144/jgs2023-081.
2. Cope, J. C. W.; Bevins, R. E. (January 1993). "The stratigraphy and setting of the Precambrian rocks of the Llangynog Inlier, Dyfed, South Wales". Geological Magazine. 130 (1): 101–111. doi:10.1017/S0016756800023761.