The BGS Lexicon of Named Rock Units — Result Details

Dart Formation

Computer Code: DART Preferred Map Code: DA
Status Code: Full
Age range: Neoproterozoic Era (AZ) — Neoproterozoic Era (AZ)
Lithological Description: Medium-grained gritty psammites and intercalated slightly graphitic mica schist.
Definition of Lower Boundary: Conformably overlying rocks of the Dungiven Formation (q.v.)
Definition of Upper Boundary: Overlain conformably by rocks of the Glenelly Formation (q.v.).
Thickness: c.2.5km
Geographical Limits: Dart Mountain and South Sperrins, Co. Londonderry, Northern Ireland.
Parent Unit: Argyll Group (ARGY)
Previous Name(s): Dart Formation [Obsolete Code: Use DART] (DCDF)
Dart Formation [Obsolete Entry: Use DART] (DCDS)
Dart Formation (Obsolete Code: Use DART) (-2137)
Schistose Grit Group Of Dart (-3346)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Partial Type Section  Boundary stratotype, bottom of formation: green beds (amphibolitic) above uppermost limestone unit of Dungiven Formation, Butterhope Glen. 
Reference Section  Butterhope Glen to 500m south east of Drumnaspar Bridge. 
Partial Type Section  Boundary stratotype, top of formation: Oughtboy Burn. Transition from medium-grained gritty psammites and graphitic mica schists (Dart Formation) to silvery green semi-pelite, flags and tourmaline schists (Glenelly Formation). 
Reference(s):
Arthurs, J W, 1976. The geology and metalliferous mineral potential of the Sperrin Mountains area. Geological Survey of Northern Ireland, Special Report No.1, 119pp, 2app, 2 figs, 7 tables, 102 maps. 
Hartley, J J, 1938. The Dalradian rocks of the Sperrin Mountains and adjacent areas in Northern Ireland. Proceedings of the Royal Irish Academy, Vol.XLIV, section B, 141-171. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable