The BGS Lexicon of Named Rock Units — Result Details

Pont-Yr-Hafod Group

Computer Code: PY Preferred Map Code: notEntered
Status Code: Full, pending ratification
Age range: Neoproterozoic Era (AZ) — Neoproterozoic Era (AZ)
Lithological Description: Highly feldspathic tuffs varying in texture from conglomeratic to fine-grained, and in colour from pink and green to maroon and purple.
Definition of Lower Boundary: Drawn at the base of the coarse purple and green Feldspathic Tuff Formation where underlying rocks are not seen.
Definition of Upper Boundary: Drawn at the conformable upward passage from the Rhyolitic Tuffs Formation of the Pont-Yr-Hafed Group to the rhyolitic and keratophyric tuffs and lavas of the Rhindaston and Gignog Group.
Thickness: Not known.
Geographical Limits: South west Wales between Haycastle and Tre-Rhos, Dyfed.
Parent Unit: Not Entered (?)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Type Area  Between Haycastle and Tre-Rhos. 
Thomas, H H and Jones, O T, 1912. On the Pre-Cambrian and Cambrian rocks of Brawdy, Haycastle and Brimaston, (Pembrokeshire). Quarterly Journal of the Geological Society of London, Vol.68, 374-401. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable