The BGS Lexicon of Named Rock Units — Result Details

Holm Farm Limestones Bed

Computer Code: HMFL Preferred Map Code: HF
Status Code: Full
Age range: Hettangian Age (JH) — Hettangian Age (JH)
Lithological Description: Group of three limestone units separated by mudstone beds. Each unit may comprise up to four limestone beds, the lowest (Bed X of Brandon et al, 1990) is shelly and rubbly and includes bivalves and ammonites, the uppermost is bioclastic and pyritic packstone/grainstone, shelly, pale grey, weathering pale brown, with abundant coarse sand-grade shell debris, and a fauna including serpulids, gastropods, bivalves and echinoid spines, and also the trace fossil Kulindrichnus. The uppermost limestone forms a strong positive feature.
Definition of Lower Boundary: Change up from grey, calcareous mudstone with rare thin limestones of undifferentiated Barnby Member; at 87.35m depth in type section Fulbeck Airfield Borehole (SK95SW/17).
Definition of Upper Boundary: Change up into grey, calcareous mudstone of undifferentiated Granby Member; at 82.76m depth in type section Fulbeck Airfield Borehole (SK95SW/17).
Thickness: 4.5 to 5m; 4.59m in type section.
Geographical Limits: East Midlands: north Leicestershire to Linclonshire. Not recognised in north Lincolnshire, or south Leicestershire, where it passes south into part of the more argillaceous Rugby Limestone Member of the Blue Lias Formation (Ambrose, 2001).
Parent Unit: Granby Member (GRBL)
Previous Name(s): Holm Farm Limestone (-3472)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Fulbeck Airfield Borehole F/B5 (SK95SW/17). 
Reference(s):
Ambrose, K, 2001. The lithostratigraphy of the Blue Lias Formation (Late Rhaetian-Early Sinemurian) in the southern part of the English Midlands. Proceedings of the Geologists' Association, Vol.112, 97-110. 
Brandon, A, Sumbler, M G and Ivimey-Cook, H C, 1990. A revised lithostratigraphy for the Lower and Middle Lias (Lower Jurassic) east of Nottingham, England. Proceedings of the Yorkshire Geological Society, Vol.48, 121-141. 
Berridge, N G, Pattison, J, Samuel, M D A, Brandon, A, Howard, A S, Pharaoh, T C and Riley, N J. 1999. Geology of the Grantham district. Memoir of the British Geological Survey, sheet 127 (England and Wales). 
Carney, J N, Ambrose. K and Brandon A, 2002. Geology of the Melton Mowbray district - a brief explanation of the geological map. British Geological Survey Sheet Explanation, Sheet 142 (England and Wales). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E127 E142 E126