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): Schistose Grit Group Of Dart (-3346)
Dart Formation [Obsolete Code: Use DART] (DCDF)
Dart Formation [Obsolete Entry: Use DART] (DCDS)
Dart Formation (Obsolete Code: Use DART) (-2137)
Alternative Name(s): none recorded or not applicable
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). 
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. 
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