|Coarse psammite with quartz segregations and K-feldspar pegmatite veins (Owencam Formation), Escort Port.
|Escort Port is a site containing representative strata of the Torr Head and the Owencam Formations (Argyll Group). These strata are well exposed in a series of cliff and foreshore sections.
|Escort Port lies in a natural rocky inlet about 800m west of Torr Head. The site is surrounded by steep sea-cliffs with access to the shore along the unfenced farm track which runs north-east from the bridge at [D223 406] on the Torr Head Road.
|On the first edition of the one inch to one mile geological map of the area (Ballycastle, Sheet 8) (Geological Survey of Ireland, 1887), the rocks at Escort Port were classified simply as "gneiss and limestone" and referred to collectively within the category "crystalline schists".
|McCallien (1931) and Bailey & McCallien (1934) produced the first detailed lithostratigraphic map of north-east Antrim and adopted the Dalradian lithostratigraphic nomenclature which was currently in use in Scotland. This stratigraphy was predicated on a structural interpretation which viewed north-east Antrim as the south-westerly continuation of regional-scale, recumbent fold structures already identified on the Cowal Peninsula, south-west Scotland (Gunn, 1897). In the stratigraphy proposed by Bailey & McCallien, the strata at Escort Point formed part of the Lough Tay Limestone and the Ben Lui Schist.
|On the second edition of the Ballycastle Sheet, (Geological Survey of Northern Ireland, 1963) and the accompanying Geological Memoir (Wilson et al., 1966), the rocks at Escort Port were referred to as "Schistose grit and quartz-schist & Metamorphic Limestone." This map delineated several broad lithological subdivisions in the Dalradian but did not use local formation names.
|A more formal approach to lithostratigraphic nomenclature for the Dalradian of north-east Antrim emerged on the first edition of the Solid Geology Map of Northern Ireland (Geological Survey of Northern Ireland, 1977) and, for the first time, local lithostratigraphic names were adopted for the principal rock units. The strata at Escort were referred to as the Torr Head Limestone and the Murlough Bay Schist.
|Arthurs (1976) produced a major revision of the Dalradian stratigraphy of north-east Antrim defining a new lithostratigraphic framework. The Murlough Bay Schists were now subdivided and the term Owencam Formation applied to the 4km wide belt of mixed psammites and schists outcropping directly to the north-west of the Torr Head Formation. Although Arthurs' revision was based on reconnaissance mapping, and further detailed work is required in this area, his lithostratigraphy formed the basis for the second edition of the Solid Geology Map of Northern Ireland (Geological Survey of Northern Ireland, 1997), see table below.
|TABLE TO BE ADDED Dalradian stratigraphy and ESCR sites in North-east Co. Antrim.
|Along the path which runs from the bridge at [D223 406] to Escort Port, there are several outcrops of schistose grit and quartz schist (Owencam Formation) and, close to a recently cut section through till, fresh exposures of reddish-stained quartz-mica- schist and phyllite.
|All of these rocks are foliated and locally flaggy where there is a well developed north-westerly dipping spaced cleavage (S2). In parts, this fabric strongly crenulates an earlier composite fabric(s) (S0\S1). The more phyllitic lithologies also have a well developed intersection lineation (S0\S1 on S2).
|In the sea-cliffs directly north of Escort Bay and on the foreshore there are several outcrops and numerous large slumped blocks of coarse-grained quartz-mica schist and quartz psammite (Owencam Formation). These rocks have a distinctive striped appearance and are locally calcareous.
They contain abundant thin quartz segregations which are generally parallel to the regionally dominant S2 cleavage. Minor folds occur throughout the area commonly accompanied by quartz and potash-rich feldspar pegmatite veins which locally contain massive black chlorite.
|Thinly-bedded metalimestone (Torr Head Formation), Escort Port.
|On the foreshore, at the southern side of Escort Port, there are several outcrops of a thinly interbedded succession of pale grey to white and greyish-blue, coarse to very coarse grained metalimestone with thin albite-biotite-chlorite-epidote phyllite (green beds).
These strata belong to the Torr Head Formation which lies beneath the Owencam Formation in what is a structurally inverted sequence. The beds in this area are locally folded with tight and sometimes disharmonic structures plunging at 10°NE.
|Metabasite intrusion, south side of Escort Port.
|A shear 20m high sea-cliff composed of coarse to very coarse-grained hornblende metabasite (epidiorite) cut by a series of flat-lying white quartz veins represents the southern limit of safely accessible outcrop at the Escort Port site.
|Escort Port is a site of stratigraphic significance of national importance. The site provides safe access to high quality exposures of the topmost part of the Owencam Formation and the lowermost part of the Torr Head Formation. It provides geologists with an opportunity to study at close hand the important association of carbonate, siliciclastic and metavolcanic rocks which typify this particular stratigraphic interval in the Dalradian in Northern Ireland.
|The rocks at Escort Port reflect important environmental changes which took place towards the end the Middle Dalradian (600 Ma). At this time, the continental crust along the margin of Laurentia came increasingly under the influence of an extensional tectonic regime and the comparatively stable, shallow-water shelf depositional environments which had characterised much of Lower and Middle Dalradian times, gave way to less stable conditions. Crustal extension and thinning was accompanied by a major upsurge in basic volcanic activity and the eruption of basaltic lavas and associated tuffs (green beds) into comparatively shallow near shore marine environments typified by the Tayvallich Subgroup. Throughout the Dalradian belt in Northern Britain, this stratigraphic interval is characterised by the intimate association of limestone and basaltic magmatism as seen at Escort Port and at Torr Head (Torr Head Formation) directly to the south.
|During the Caledonian Orogeny Dalradian rocks underwent intense deformation and regional metamorphism. In North-east Antrim, as in Scotland and the Sperrin Mountains deformation was complex and polyphase resulting in folding and the formation of up to four recognisable fold phases and related cleavages (Arthurs, 1976; Goldring, 1961).
|Structurally, the rocks at Escort Port lie close to the core on the inverted lower limb of the Altmore Anticline, the north-east to south-west trending recumbent anticline that is the south-westerly continuation into Northern Ireland of the Cowal Anticline.
|Deformation was accompanied by regional metamorphism. Metamorphic mineral assemblages in the rocks at Escort Port indicate that this was a relatively low-grade metamorphic event, within the quartz-albite-muscovite-chlorite sub-facies of the Greenschist Facies.
|Escort Port is a site of national stratigraphic significance offering safe access to strata representative of the Owencam and Torr Head Formations of the Argyll Group (Middle Dalradian).
For site specific information and references on other Dalradian sites in North-east Antrim see the following sites:
|Key Site 155 - Benvan Key Site 157 - Torr Head Key Site 158 - Altmore Burn Key Site 159 - Leckpatrick Point Key Site 160 - Carnaneigh Key Site 161 - Loughan Bay Key Site 162 - Loughareema Channel Key Site 163 - Knocknacarry Bridge Key Site 164 - Cushendun Bay and Rock Port
|For site specific information and references on other Dalradian sites in the Sperrin Mountains, Londonderry and Tyrone see the following sites:
|For Central and Southern Sperrin Mountains:
|Key Site 130 - Butterlope Glen Key Site 131 - Craig Key Site 132 - Mullaghcarbatagh Key Site 133 - Henry's Bridge, Glensass Burn Key Site 134 - Oughtboy Burn Key Site 135 - Garvagh Burn Key Site 136 - Barnes Gap Key Site 137 - Barnes Burn Key Site 138 - Golan Burn Key Site 139 - Glendarragh Burn, Glenlark Key Site 140 - Mountfield Old Quarry Key Site 141 - McNally's Burn, Broughderg
|For North Sperrin Mountains and Londonderry:
|Key Site 142 - Letterbrat Quarry Key Site 143 - Banagher Glen Quarry Key Site 144 - Strabane Quarry Key Site 145 - Glenmornan River, Artigarvan Key Site 146 - Balix Hill Key Site 147 - Drain Quarry Key Site 148 - Kildoag Quarry Key Site 149 - Loughermore Mountain Key Site 150 - Burntollet and Tamnymore Wood Key Site 151 - Dog Leap, Limavady Key Site 152 - Kittybane Quarry Key Site 153 - Prehen Quarry Key Site 154 - Creevagh Hill Old Quarry
|For general information on the Dalradian rocks of Northern Ireland see the following site:
|Key Site 124 - The Dalradian Rocks of Northern Ireland
|For general and site specific information on the Pre-Dalradian rocks of Northern Ireland see the following site:
|Key Site 123 - The Pre-Dalradian Rocks of Northern Ireland
|For general information and an extensive reference list on the Precambrian of Northern Ireland see the following site:
|Key Site 122 - An Introduction to the Precambrian of Northern Ireland
|Arthurs, J.W. 1976a: The geology and metalliferous mineral potential of the Sperrin Mountains area Geological Survey of Northern Ireland Special Report
|Bailey, E.B. and McCallien, W.J. 1934: The metamorphic rocks of North-east Antrim Transactions of the Royal Society of Edinburgh: Earth Sciences, vol. 58, pp.163-177
|Golding, D.C. 1961: The relationship of the micro-fabric to the small-scale structures of the Dalradian of north-eastern Antrim Proceedings of the Royal Irish Academy, vol. 61 pt. B, pp.345-367
|Gunn, W., Clough, C.T. and Hill, J.B. 1897: The Geology of Cowal Memoir of the Geological Survey of Scotland
|McCallien, W.J. 1931: A contribution to the correlation of the Dalradian rocks of Scotland Geological Magazine, vol. 68, pp.153-175
|Wilson, H. E. and Robbie, J. A. 1966: Geology of the country around Ballycastle. Memoirs of the Geological Survey Northern Ireland,
|GSI (1887). 1:63,360 Geological Sheet 8 (Ballycastle), Dublin, OS for GSI / GSNI (1963). 1:63,360 Ballycastle, Northern Ireland Sheet 8, Drift, Southampton, OS for GSNI / GSNI (1977). 1:250,000 Northern Ireland, Solid Geology (1st edition), Southampton, OS for IGS / GSNI (1997). 1:250,000 Northern Ireland, Solid Geology (2nd edition), BGS, Keyworth, Nottingham