The BGS Lexicon of Named Rock Units — Result Details

Ailnack Phyllite And Limestone Formation

Computer Code: APAL Preferred Map Code: SYMB
Status Code: Full
Age range: Neoproterozoic Era (AZ) — Neoproterozoic Era (AZ)
Lithological Description: Semipelites with subsidiary psammites, generally phyllitic, more calcareous in its upper part. Distinctive white limestone bands typically. Also grey finely crystalline limestones and calc-silicate bands. In Glenlivet-Glen Suie area divided into three members.
Definition of Lower Boundary: At upper limit of quartzite of the Corryhabbie Quartzite Formation and at lowest occurrence of white limestone or semipelite.
Definition of Upper Boundary: Rapid gradation from calcareous semipelite and limestone to graphitic pelite/semipelite of Clashnoir Semipelite Formation.
Thickness: 40 - 600m.
Geographical Limits: Extends from Muckle Allt Venney (Glen Markie) southwest to Glenfiddich, Upper Glenlivet and Glen Suie to the Kylnadrochit-Fodderletter area (Strathavon), Water of Ailnack section and Glen Avon (Burn of Little Fergie to Foal's Crag) and Glen Builg. Southern limit - Loch Builg.
Parent Unit: Ballachulish Subgroup (DABH)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Central section of water of Ailnack gorge around junction with Allt Dearcaige. 
Reference Section  Tor of Suie area, Glen Suie. 
Reference(s):
Memoir of the British Geological Survey, Sheet 75, in preparation. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S075 S086