The BGS Lexicon of Named Rock Units — Result Details

Arch Farm Sandstone Formation

Computer Code: ARFS Preferred Map Code: ARFS
Status Code: Pending Upgrade
Age range: Visean Stage (CV) — Visean Stage (CV)
Lithological Description: Green to grey, fine- to medium-grained, laminated or cross laminated sandstone in beds up to 1.7m thick, with pebble-rich lenses and shelly lags with Lingula fragments and seams up to several centimetres thick, consisting of green mudstone and siltstone with Lingula. All lithologies are seen as rip-up clasts in the basal parts of the sandstone beds.The upper part of the formation comprises coarse-grained, calcareous sandstone, with pedogenic fabrics, and conglomerate.
Definition of Lower Boundary: A sharp, conformable base of green to grey, fine- to medium-grained sandstone with Lingula, of the Arch Farm Sandstone Formation, above the brown to green-grey medium to coarse-grained sandstone and conglomerate of the Calke Abbey Sandstone Formation; seen as a prominent step on gamma-ray logs.
Definition of Upper Boundary: The top of a medium- to coarse-grained pebbly sandstone, overlain by green, slickensided, smectite-rich mudstone with about 4 mm ferruginous concretions of the Arch Farm Sandstone Formation, sharply overlain by pale grey to white calcareous sandstone of the Cloud Hill Dolostone Formation.
Thickness: Measured as 9 m thick in the Ticknall Borehole, as detailed in the reference stratotype information.
Geographical Limits: Present in the subsurface in the area of Hathern Shelf, Loughborough District [SK32].
Parent Unit: Not Applicable (-)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Type Section  BGS Ticknall Borehole (SK32SE/103), at between 101.3 m and 92.3 m depth, displaying the entire thickness of the formation. 
Carney, J N, Ambrose, K and Brandon, A. 2001. Geology of the country between Burton, Loughborough and Derby. Description of 1:50k Sheet 141 (England and Wales). 
Ambrose, K and Carney, J N. 1997. Geology of the Calke Abbey area: 1:10 000 Sheet SK32SE. BGS Technical Report WA/97/17. 
1:50K maps on which the lithostratigraphical unit is found, and map code used: