The BGS Lexicon of Named Rock Units — Result Details

Grumack Hill Quartzite Member

Computer Code: GHQU Preferred Map Code: SYMB
Status Code: Full
Age range: Neoproterozoic Era (AZ) — Neoproterozoic Era (AZ)
Lithological Description: Quartzite, buff, grey to off-white and gritty psammite.
Definition of Lower Boundary: Junction with underlying pelites (Corinacy Pelite Member).
Definition of Upper Boundary: Junction with overlying, highly magnetic biotite-andalusite-schist (Garnel Burn Pelite Member of the Clashindarroch Formation).
Thickness: c. 400m
Geographical Limits: NW flank of watershed ridge (including Grumack Hill) on the SE side of the River Deveron Valley, between NJ 448 355 and Hill of Bank (NJ 388 290) NB The outcrop does not include the actual summit of Grumack Hill.
Parent Unit: Blackwater Formation (BLWR)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Bouldery outcrops on a series of features on the northwest flank of Grumack Hill c.250m northeast of the source of Raigie Burn. 
Reference(s):
Fettes, D J, Lesley, A G, Stephenson, D and Kimbell, S F, 1991. Disruption of Dalradian stratigarphy along the Portsey Lineament from new geological and magnetic surveys. Scottish Journal of Geology, Vol.27, 57-73. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S086 S075