Chapel House Limestone Formation
Chapel House Limestone Formation is part of the Great Scar Limestone Group
The lower part of the succession is dominated by mid to mid–pale grey, medium- and coarse-grained calcarenite, oolitic grainstones interbedded with conglomerates, ‘mixed laminites’ (interbedded siltstone with sandstone and mudstone laminae), dolomicrites and fenestral or algal lime-mudstones. Argillaceous wackestones occur locally in the upper part of the formation.
Shallow marine (see Murray, 1983).
The type section is the Chapel House Borehole (BGS Registration Number SD96NE/1) (SD 9726 6647), near Kilnsey, Yorkshire, which records the entire thickness of the formation (33.8 m) from 56.3 to 90.1 m depth (see Arthurton et al., 1988).
Lower and upper boundaries
The base is drawn at the base of the conglomerate of the Chapel House Limestone Formation where it rests with significant non-sequence on the deeply fissured limestone top surface of the Stockdale Farm Formation (Figure 15, Column 6), which comprises limestone, siltstone and mudstone. It lies directly on Lower Palaeozoic rocks elsewhere.
The top of the formation is drawn at the sharp conformable upward passage from grainstone of the Chapel House Limestone Formation to darker limestones of the Scaleber Force Limestone Member (Kilnsey Formation).
Maximum of about 56 m adjacent to the Middle Craven Fault, and 33.8 m thick in the type section (see above).
Distribution and regional correlation
A series of inliers in the southern part of the Askrigg Block, North Yorkshire, including Gordale Beck (SD 91 65), Stainforth Force, River Ribble (SD 82 67), and Barrel Sykes, north of Settle (SD 82 64). The formation is proved elsewhere in the subsurface of the Settle area in boreholes.
Age and biostratigraphical characterisation
Arundian. Arthurton et al. (1988) record the presence of the corals Michelinea megastoma and Palaeosmilia murchisoni from the top and base of the formation respectively, and the foraminifers Ammarchaediscus bucullentus, Eoparastaffella simplex, Glomodiscus miloni, Latiendothyranopsis menneri solida and Rectodiscus sp., which confirm its Arundian age.
- Arthurton, R S, Johnson, E W, and Mundy, D J C.1988.Geology of the Country around Settle.Memoir of the British Geological Survey, Sheet 60 (England and Wales).
- Murray, D W.1983.The limestone and dolomite resources of the country around Settle and Malham, North Yorkshire (with notes on the hard-rock resources of the Horton-in-Ribblesdale area): description of parts of 1:50 000 geological sheets 50 and 60.Mineral Assessment Report Institute of Geological Sciences, No. 126.