The BGS Lexicon of Named Rock Units — Result Details

Macduff Formation

Computer Code: MCD Preferred Map Code: Mcd
Status Code: Full
Age range: Neoproterozoic Era (AZ) — Neoproterozoic Era (AZ)
Lithological Description: Metagreywacke: interbedded psammite and semipelite with subsidiary pelite. Contains major units of pebbly psammite, particularly in basal part (Knock Head Grit Member). Metamorphosed to slates, phyllites and mica-schists. Contains Boulder Bed at Macduff (glaciomarine diamicton). Minor calc-silicate pods. Contains andalusite, cordierite and locally staurolite porphyroblasts.
Definition of Lower Boundary: Change from calcareous semipelite to non-calcareous lithologies at top of Whitehills Grit Formation; commonly marked by change to locally coarsely gritty psammite of Knock Head Grit Member.
Definition of Upper Boundary: Not seen - highest beds are in centre of Turriff Syncline.
Thickness: Up to 5.5km, but could be less, as there is repetition by folding.
Geographical Limits: From Moray Firth coast [NJ 6514 6564-NJ 776 643], southwards to northern margin of Insch intrusion [NJ 650 325-NJ 725 305].
Parent Unit: Southern Highland Group (SOHI)
Previous Name(s): Macduff Slates (-1685)
Boyndie Bay Formation [Obsolete Name And Code: See MCD] (DCBD)
Macduff Slate [Obsolete Name And Code: Use MCD] (DCMS)
Boyndie Bay Group (-203)
Replaced By Macduff Formation (*259)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Coastal section from Craig Neen, Whitehills to Grip of Twinely (centre of Turriff Syncline). 
Reference(s):
Harris, A L, Haselock, P J, Kennedy, M J and Mendum, J R, 1994. The Dalradian Supergroup in Scotland, Shetland and Ireland. 33-53 in Gibbons, W E and Harris, A L (editors). A revised correlation of Precambrian rocks in the British Isles. Special Report of the Geological Society, London, No.22. 
Stephenson, D, et al. 1993. Stratigraphy and correlation of the Dalradian rocks of the East Grampian Project area. British Geological Survey Technical Report WA/93/91. 
Stephenson, D and Gould, D , 1995. British Regional Geology: the Grampian Highlands (4th edition). (London: HMSO for the British Geological Survey), 67-68. 
Read, H H, 1923. Geology of the country around Banff, Huntly and Turriff, Lower Banffshire and north-west Aberdeenshire. Memoir of the Geological Survey, Scotland Sheets 86 and 96 (Scotland). 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S096 S096 S086 S086 S087