ESCR - Drain Quarry

Earth Science Conservation Review

Summary Full report
Drain Quarry	Tyrone

Site number:	147
ESCC:	ED
Locality Type:	Quarry (disused)	Status:	ESCR
Grid Reference:	C458019 Centroid
Google maps:	54.86319,-7.28673
County:	Tyrone	Council area:	Derry City & Strabane District Council
Period:	Precambrian
Stages:	Dalradian
Lithostrat:	Alla Glen Limestone Member, Claudy Formation

Site Description
Disused limestone quarry, Drain Quarry, Donemana, Co. Tyrone.
Highlights:
The disused and partially flooded quarry at Drain contains abundant fresh outcrop of the Alla Limestone Member, an important stratigraphic marker horizon within the Claudy Formation (Southern Highlands Group, Upper Dalradian). The site offers an opportunity to study lithological variation within the Alla Limestone as well as key structural elements.
Introduction:
This site is located on the western side of a large disused and flooded quarry in the townland of Drain approximately 2km south-east of Dunnamanagh (Donemana). This is an area of dissected hill and valley terrain to the west of the main Sperrin Mountains. Access to the site is via a locked gate on the Gortaclare Road between Dunnamanagh and Liscloon. On the first edition of the one inch to one mile geological map (Sheet 17, Strabane) (Geological Survey of Ireland, 1988, Kinahan et al., 1889) the limestone at Drain was not represented although an extensive E-W striking limestone unit was mapped approximately 1.5km south of the quarry and numerous small, detached outcrops of limestone were mapped in the area to the east and north-west of Drain. In the stratigraphy proposed for this area by Arthurs (1976), the Claudy Formation contains two laterally extensive limestone members, the Bonds Glen Limestone and Alla Glen Limestone, see table below. These limestones appear to be conformable with typical psammites and quartzites of the Claudy Formation in this area. The entire succession is located on the northern, upwards facing limb of the Sperrin Overfold and consequently youngs towards the north-west. TABLE TO BE ADDED Dalradian stratigraphy and ESCR sites in the northern Sperrin Mountains.
Description:
Drain Quarry contains abundant high quality exposure of the Alla Glen Limestone. This is a well-stratified sequence of light-grey and greyish-blue, coarse crystalline and "sugary" limestones (up to 1m thick). The limestone units are generally separated by thin (<1cm thick) partings and slivers of grey and silvery grey to black sometimes graphitic phyllite and pelite. Locally both the limestone and the argillaceous partings contain significant amounts of muscovite. Pyrite occurs throughout these rocks in the form of euhedral cubes and coatings on joint surfaces. Throughout the accessible parts of the quarry, cleavageedding relationships are clearly visible along with minor folding.. Blue, grey and white compositional banding within the limestone units together with bedding surfaces (S0), have a broadly coplanar S1 cleavage which is particularly apparent in the argillaceous interbeds. Both S0 and S1 are cut by a northwards dipping penetrative spaced- cleavage (S2). This S2 fabric crenulates the earlier (S0 and S1) surfaces and in places is clearly axial planar to northerly plunging minor F2 folds. Folded limestone and phyllite (Alla Limestone Member, Claudy Formation), Drain Quarry. All of these minor folds and lithons show a consistent southerly sense of vergence.
Importance:
This is an important site which offers access to high quality outcrop of limestones within the Claudy Formation in an otherwise poorly exposed area. These strata display many informative sedimentological variations. There is also clear exposure of key structural relationships. It has already become apparent that the limestone members within the Claudy Formation are important marker horizons with a key role to play in establishing local stratigraphy and structure. The exposures at Drain Quarry will come under renewed scrutiny as the Geological Survey of Northern Ireland embarks on the mapping of the Strabane (Sheet 17) area in the near future. It is also anticipated that the site will be a key locality in a planned scientific investigation of the provenance of Dalradian limestones in both Northern Ireland and Scotland.
Interpretation:
The rocks exposed at this site formed from sediments originally deposited in a near-shore shallow water marine environment. During the late-Caledonian Orogeny, these rocks were deformed, folded and subjected to regional metamorphism. They have mineral assemblages which typically include chlorite, biotite, and muscovite and are consistent with metamorphic conditions within the Greenschist Facies of the Barrovian Facies Series (Arthurs, 1976). Structurally, these rocks now lie on the northern, upwards facing limb of the Sperrin Overfold (F2) and have a well developed, penetrative, axial planar fabric (S2). The correlation proposed by Arthurs (1976) between the Claudy Formation and the Dart Formation on opposite limbs of the Sperrin Overfold, does not account for the major lithological differences between the two formations. The Claudy Formation consists predominantly of near-shore, shallow-water lithologies (limestone, quartzite, quartz-feldspar psammite whereas the Dart Formation is a typically coarse-grained turbidite sequence derived from a continental source with sporadic but widespread input of mafic volcanic debris (Harris et al., 1994). It is possible that the Claudy Formation merely represents the more proximal shelf facies which changes laterally southwards into the open basinal marine turbidite facies of the Dart. There is also the possibility that the entire sequence was been foreshortened as a result of the D2 and D3 deformations which were responsible for south-east and east-south-easterly directed folding and thrusting in the Sperrin Mountains.
Conclusions:
This is an important site of national significance which displays to good effect many geological features worthy of conservation. It is anticipated that the site will pay a key role in ongoing research into the stratigraphy and structure of the Dalradian rocks of Northern Ireland.
Notes:
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 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 site specific information and references on other Dalradian sites in North-east Antrim see the following sites: Key Site 155 - Benvan Key Site 156 - Escort Port 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 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

Keywords
Rocks:	Limestone

Access
Management:
Drain Quarry is currently derelict and appears to have been so for a number of years. All the quarry plant has been dismantled and removed. Only the concrete and block foundations remain. The site is fenced and access is via a locked gate. A large part of the quarry floor is flooded to an undetermined depth. This makes all but the faces on the western side of the quarry inaccessible. Any further significant rise in the water level in the quarry could result in some of the exposures which currently can be safely reached becoming inaccessible. The free-standing pillar-like outcrop where most of the best examples of structural elements are seen, would be at particular risk in this respect. There is some evidence of tipping in the quarry. This is mostly metal and old cars (1950's and 1960's models). There was no evidence of more recent tipping. Extra care should be taken by anyone visiting this site because the quarry is flooded, and working faces are precipitous and in places unstable.

Access

Management:

Drain Quarry is currently derelict and appears to have been so for a number of years. All the quarry plant has been dismantled and removed. Only the concrete and block foundations remain. The site is fenced and access is via a locked gate. A large part of the quarry floor is flooded to an undetermined depth. This makes all but the faces on the western side of the quarry inaccessible. Any further significant rise in the water level in the quarry could result in some of the exposures which currently can be safely reached becoming inaccessible. The free-standing pillar-like outcrop where most of the best examples of structural elements are seen, would be at particular risk in this respect. There is some evidence of tipping in the quarry. This is mostly metal and old cars (1950's and 1960's models). There was no evidence of more recent tipping. Extra care should be taken by anyone visiting this site because the quarry is flooded, and working faces are precipitous and in places unstable.

References (3)
Arthurs, J.W., 1976a. The geology and metalliferous mineral potential of the Sperrin Mountains area Geological Survey of Northern Ireland Special Report.
Harris, A.L., Haselock, P.J., Kennedy, M.J. & Mendum, J.R., 1994. The Dalradian Supergroup in Scotland, Shetland and Ireland Geological Society of London Special Report, In A revised correlation of Precambrian rocks in the British Isles.
Kinahan, G.H., Wilkinson, S.B., Nolan, J. & Eagan, B.A., 1889. Explanatory Memoir to accompany Sheet 17 of the maps of the Geological Survey of Ireland Memoirs of the Geological Survey of Ireland.

Map(s):	GSI (1888). 1:63,360 Geological Sheet 17 (Strabane), Dublin, OS for GSI
Record type:	ESCR report
Entered by:	E M Porter
Last updated:	8 Jan 2005

Enlander, I., Dempster, M. & Doughty, P., 2026. Drain Quarry, County Tyrone, site details. [In] Earth Science Conservation Review.
https://www.habitas.org.uk/escr/site.php?item=147. Accessed on 2026-11-06.