Askham Limestone Member
Limestone, dark grey, well-bedded, wackestone and packstone, porcellanous in parts. Prominent layers with algal oncoliths and coral colonies. The member is split into 2 leaves by a thin layer of red-brown mudstone.
The type section is an abandoned roadside (east side of minor road) quarry (NY 583 171) beside Wintertarn Farm, by Shap, Cumbria (Rowley, 1969) where the limestone, a mid grey biomicrite, is divided into two parts by an algal horizon, most likely the equivalent of the Girvanella Bed of Garwood (1913). A reference section is the Flusco Lodge disused quarry (NY 474 282), 3.8 km west of the M6 Penrith interchange, where a full section of the limestone is preserved, along with the top part of the underlying Wintertarn Sandstone Member, Tyne Limestone Formation (McCormac, 2001).
Lower and upper boundaries
The base of the member is sharp, occurring at the base of a limestone bed overlying the mainly sandstone of the Wintertarn Sandstone Member, Tyne Limestone Formation (Figure 14, Column 3).
The upper boundary of the member is taken at the base of the overlying shelly marine mudstone within the Alston Formation Yoredale facies depositional cycle.
Between 12 and 14.7 m.
Distribution and regional correlation
North Cumbria and Edenside, west of Pennine–Dent Fault zone.
Asbian to Brigantian.
- Rowley, C R.1969.The stratigraphy of the Carboniferous Middle Limestone Group of West Edenside, Westmorland.Proceedings of the Yorkshire Geological Society, Vol. 37, 329–350.
- Burgess, I C, and Holliday, D W.1979.Geology of the country around Brough-under-Stainmore.Memoir of the Geological Survey of Great Britain, Sheet 31, parts 25 and 30 (England and Wales).
- Dunham, K C.1990.Geology of The Northern Pennine Orefield: Volume 1, Tyne to Stainmore (2nd edition).Economic Memoir of the British Geological Survey, Sheets 19 and 25, parts 13, 24, 26, 31 and 32 (England and Wales)
- Arthurton, R S, and Wadge, A J.1981.Geology of the country around Penrith.Memoir of the Geological Survey of Great Britain, Sheet 24 (England and Wales)
- McCormac, M.2001.The Upper Palaeozoic rocks of the Shap and Penrith district, Edenside, Cumbria.British Geological Survey Research Report, RR/01/10.
- Garwood, E J.1913.The Lower Carboniferous succession in the north-west of England.Quarterly Journal of the Geological Society, Vol. 68, 449–596.