The BGS Lexicon of Named Rock Units — Result Details

Forth Formation

Computer Code: FH Preferred Map Code: notEntered
Status Code: Pending Upgrade
Age range: Marine Isotope Stage 2 (QMIS002) — Marine Isotope Stage 1 (QMIS001)
Lithological Description: Varies from muds and silty muds to sands and gravelly sands. The former muddy lithologies tend to occur mainly in the lower part of the sequence. NOTE: In this area (56 deg north, 3 deg west + 56 deg north, 4 deg west) it has been possible to subdivide the formation into two members. Unfortunately, although this unit can be extended over a wide area of the west central North Sea, it has not been possible to subdivide the unit elsewhere without present knowledge.
Definition of Lower Boundary: In the Tay-Forth area (1:250,000 Sheet 56 deg. north, 4 deg. west) the Forth Formation generally rests unconformably on the St Abbs/Wee Bankie Formations or rockhead. Locally it may rest conformably on the St Abbs Formation. Further east in the Marr Bank/Devil's Hole areas (56 deg. north, 2 deg. west, + 56 deg.) the unit may form an infill to deep erosive channels hence resting unconformably on the pre-existing sediments.
Definition of Upper Boundary: Top of unit is unconformably overlain by seabed sediments.
Thickness: Varies from < 5 metres - 60 metres.
Geographical Limits: Not defined.
Parent Unit: Reaper Glacigenic Group (REAP)
Previous Name(s): Forth Beds (-2800)
Alternative Name(s): none recorded or not applicable
Stratotypes:
none recorded or not applicable
Reference(s):
Thomson, M E, and Eden, R A. 1977. Quaternary deposits of the central North Sea, 3. The Quaternary sequence in the west-central North Sea. Report of the Institute of Geological Sciences, No. 77/12. 
Stoker, M S, Balson, P S, Long, D, and Tappin, D R. 2011. An overview of the lithostratigraphical framework for the Quaternary deposits on the United Kingdom continental shelf. British Geological Survey Research Report, RR/11/03. 48pp. 
Stoker, M S, Long, D, and Fyfe, J A. 1985. A revised Quaternary stratigraphy for the central North Sea. Report of the British Geological Survey, Vol. 17, No. 2. 
Gatliff, R W, Richards, P C, Smith, K, Graham, C C, McCormac, M, Smith, N J P, Long, D, Cameron, T D J, Evans, D, Stevenson, A G, Bulat, J, and Ritchie, J D. 1994. United Kingdom offshore regional report: the geology of the central North Sea. (London: HMSO for the British Geological Survey.) 
Cameron, T D J, and Holmes, R. 1999. The Continental Shelf. 125-139 in A revised correlation of Quaternary deposits in the British Isles. Bowen, D Q (editor). Special Report of the Geological Society of London, No. 23. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable