The BGS Lexicon of Named Rock Units — Result Details

Ham Hill Limestone Member

Computer Code: HHS Preferred Map Code: HH
Status Code: Pending Upgrade
Age range: Toarcian Age (JT) — Toarcian Age (JT)
Lithological Description: A brown, shelly, bioclastic limestone, parallel- bedded and cross-bedded, interpreted to have been deposited in a shallow marine tidal channel.
Definition of Lower Boundary: The base displays a change upward from sands or sandstones of undivided Bridport Sand Formation into bioclastic limestone.
Definition of Upper Boundary: The top is generally a non-sequence displaying a sharp change upward from bioclastic limestone to cream or grey shelly or ooidal limestone or calcareous mudstone of the Inferior Oolite, elsewhere it may be conformable, displaying a change up into sandy mudstone of undivided Bridport Sand Formation.
Thickness: Up to 27 m thick.
Geographical Limits: The Yeovil-Crewkerne area of south Somerset, where it wedges out laterally into undifferentiated Bridport Sand Formation.
Parent Unit: Bridport Sand Formation (BDS)
Previous Name(s): Ham Hill Stone (-3468)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Ham Hill, also known as Hamdon Hill, Yeovil, Somerset. 
Reference(s):
Prudden, H C. 1967. Excavations in the Yeovil Sands at Yew Tree Close, Yeovil. Proceedings of the Dorset Natural history and Archaeological Society, Vol. 88, 42-43. Shelfmark 00479. 
Richardson, L. 1919. The Inferior Oolite and contiguous deposits of the Crewkerne district (Somerset). Quarterly Journal of the Geological Society of London, Vol. 74, 145-173. 
Wilson, V, Welch, F B A, Robbie, J A, and Green, G W. 1958. Geology of the country around Bridport and Yeovil. Memoir of the Geological Survey of Great Britain, Sheets 327 and 312 (England and Wales). 
Buckman, S S. 1889. On the Cotteswold, Midford and Yeovil Sands, and the division between the Lias and the Oolite. Quarterly Journal of the Geological Society of London, Vol. 59, 445-458. 
Woodward, H B. 1887. Note on the Ham Hill Stone. Proceedings of the Bath Natural History and Antiquarian Field Club, Vol 6, 182-184. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E312