The BGS Lexicon of Named Rock Units — Result Details

Rhuddnant Grits Formation

Computer Code: RDD Preferred Map Code: Rdd
Status Code: Pending Upgrade
Age range: Telychian Age (ST) — Telychian Age (ST)
Lithological Description: Thinly interbedded turbidite sandstones and mudstones with abundant thicker beds of argillaceous coarse sandstone.
Definition of Lower Boundary: Base of lowest thick argillaceous sandstone bed overlying Caeran Mudstones.
Definition of Upper Boundary: Top of highest thick argillaceous sandstone bed below lower tongue of Glenyrafon Formation.
Thickness: c.1000m
Geographical Limits: Central Wales.
Parent Unit: Cwmystwyth Grits Group (CWY)
Previous Name(s): Rhuddnant Grits (Formation), Cletwr Facies [Obsolete Name And Code: Use RDD] (CLFA)
Alternative Name(s): none recorded or not applicable
Type Section  Nant Rhuddnant between upper reaches of Rhuddnant Gorge and Rhuddnant Tarn. 
Jones, O T. 1909. The Hartfell-Valentian succession in the district around Plynlimon and Pont Erwyd (north Cardiganshire). Quarterly Journal of the Geological Society of London, Vol.65, 463-536. 
1:50K maps on which the lithostratigraphical unit is found, and map code used: