ESCR - Mveela More

Earth Science Conservation Review

Summary Full report
Mveela More	Tyrone

Site number:	582
ESCC:	EO
Locality Type:	Inland exposure	Status:	ESCR
Grid Reference:	H641792 Centroid
Google maps:	54.6573,-7.00679
County:	Tyrone	Council area:	Fermanagh & Omagh District Council
Period:	Ordovician
Lithostrat:	Tyrone Volcanic Group, Copney Pillow-lava Formation

Site Description
Highlights:
The site at Mveela More is a series of closely-spaced, knolly, ice-sculpted outcrops of basaltic pillow lava. Stratigraphically these lavas form part of the Copney Pillow Lava Formation which is a prominent marker within the Ordovician Tyrone Volcanic Group. Mveela More is one of the best localities in the Tyrone Volcanic Group for studying pillow lavas and their morphological characteristics.
Introduction:
Mveela More is a compact site locate just north of the main Omagh to Cookstown Road (A505) 2km east northeast of Creggan. One of the earliest geological maps covering this area, Portlock (1843) classified all the volcanic and plutonic rocks of central Tyrone together as, "metamorphic rocks of hornblendic type" clearly distinguishing them from the mica schists of the Sperrin Mountains and the Tyrone Central Inlier. The rocks at Mveela More (Miveel Rock on the Portlock map) were classified as "trap". On the first edition of the one-inch to the mile scale geological map (Sheet 26, Draperstown, Geological Survey of Ireland, 1882) Mveela More was mapped as "pyroxenic rocks" designated as "Probably of Pre-Cambrian or Upper Laurentian Age". In the memoir, which accompanied the map, Nolan (1884) referred to Mveela More as being composed of "a very compact rock that is cellular in parts, the original cavities being filled with carbonates". The earliest detailed geological map and description of the geology of the central Tyrone Ordovician volcanic plutonic terrane was by Hartley (1933). Hartley included the rocks at Mveela More within what he referred to as the Tyrone Igneous Series. The second editions of geological Sheet 34 (Pomeroy) and Sheet 26 (Draperstown) (Geological Survey of Northern Ireland, 1979, 1995) included revised stratigraphy for the of the Ordovician igneous rocks in Central Tyrone. The volcanic rocks including those at Mveela More were included within the Tyrone Volcanic Group. More recently, the Tyrone Volcanic Group together with the closely associated Tyrone Plutonic Complex Volcanic Group have been interpreted as part of an ophiolite complex, (Hutton et al., 1985). On a regional scale, these rocks form part of the Tyrone-Girvan Sub-Terrane of the Midland Valley Terrane (Bluck, 1992).
Description:
Mveela More is a series of glacially scoured and moulded roches moutonnées with a well-developed crag and tail structure. The site consists almost entirely of fine to medium-grained basaltic lavas, and much of the outcrop has good pillow structures. Outcrops are moderately fresh beneath a thin skin of surface weathering. The principal lithology is mid-grey to black fine to medium-grained rocks of basaltic composition. These rocks are locally porphyritic with conspicuous, millimetre scale, greyish white, euhedral, plagioclase feldspar phenocrysts visible on fresh surfaces. Thin sections of the coarser lithologies show ophitic intergrowths of clinopyroxene and pale-grey plagioclase with secondary actinolitic amphibole forming fibrous outgrowths from the clinopyroxene. Much of the finer-grained groundmass is a replaced comprising by dark blue-grey chlorite. Locally the outcrop is cut by thin epidote veins. Sulphide minerals occur throughout the outcrop with pyrite in millimetre sized euhedral cubes and as smears along joint surfaces. Unlike many of the finer-grained tuffaceous lithologies in the Tyrone Volcanic Group, the Copney Pillow Lava Formation at Mveela More is not strongly deformed and many original morphological features of the pillow lavas remain. These are many superb examples of classic rounded and ovoid shaped pillows with flattening and squeezing of pillows. Individual pillows range in size ~0.3m to ~1.5m in diameter. Triple junction relationships between adjacent pillows in the pile are common although way-up (younging direction) evidence is often ambiguous as a result of deformation and stretching of the pillows. Many of the pillows have complete or partial millimetre thick surface skins which represent the devitrified outer glassy chilled surface of the lava. Relic gas vesicles are visible in some of the pillows, as are patterns of radiating contraction joints. Throughout the outcrop, there are occurrences of pale pink and occasionally red chert and fragmental hyaloclastic breccia material in the triple point area between pillows. These materials represent the interstitial sediment comprising siliceous seabed muds and the devitrified debris produced as a result of explosive interactions between the seawater and the hot lava. Greyish green variegated banded chert is particularly well exposed at the base of the southernmost crag at Mveela More.
Importance:
Mveela More is a site of national importance that has been included in many local geological field-trip itineraries. It is a valuable scientific teaching resource containing excellent examples of pillow lavas of the Copney Pillow Lava Formation (Tyrone Volcanic Group). Although pillow lavas are exposed elsewhere along strike from Mveela More (Creggan, Copney Wood), this compact site, with its lightly weathered and etched bare rock faces, provides some of the best examples of pillow lavas of any age anywhere in Northern Ireland.
Interpretation:
The rocks at Mveela More form part of a pillow lava horizon within the Tyrone Volcanic Group. These rocks form part of an island arc or back-arc sequence which formed on the northern margin of the Iapetus Ocean as oceanic crust was obducted northwards against the continental margin of Laurentia during Ordovician times. On a regional scale, the Tyrone Volcanic Group forms part of the Tyrone-Girvan Sub-Terrane of the Midland Valley Terrane and is broadly equivalent to the ophiolitic-volcanic associations at Girvan-Ballintrae in Scotland and at Clew Bay in County Mayo.
Conclusions:
Mveela is a site of national importance. It is a valuable educational and research resource providing access to high quality outcrops of pillow lavas within the Tyrone Volcanic Group.
Notes:
For information and references on sites within the Tyrone Basic Plutonic Complex see the following sites: Key Site 580 - Black Rock Key Site 581 - Scalp Hill For information and references on other sites within the Tyrone Volcanic Group see the following sites: Key Site 583 - Creggan Key Site 584 - Copney Hill Key Site 585 - Beaghbeg Key Site 586 - Bonnety Bush, Altihaskey Key Site 587 - Tullybrick Key Site 588 - Stuhanleanantawey Burn For information and references on Granitoid sites within the Caledonian Complexes of N. Ireland see the following sites: Key Site 589 - Cashel Rock Key Site 590 - Craigballyharky and Craigbardahessiagh Key Site 591 - Craiganawork, Pomeroy Key Site 592 - Tintagh, Slieve Gallion Key Site 593 - Loughmacrory Key Site 594 - Cushendun For general information and references on the Caledonian Igneous Complexes of N. Ireland, and for directions to other regional sites, see the following site: Key Site 595 - Introduction to the Caledonian Igneous Complexes of N. Ireland

Keywords
Minerals:	Epidote, Pyrite
Rocks:	Basalt, Breccia, Volcanic, Chert
Structures:	Caledonian, mineral vein, pillow lava
Relations:	Extrusion

Access
Management:
Because this is a very rocky and craggy site it is unlikely that in the future it will come under any direct threat from development. The site is located within 25m of an occupied dwelling with access limited, at present, to a narrow private lane and the dwelling house yard. Maintenance of this access is likely to be a major management priority. The rocks of the Tyrone Volcanic Group are considered to be prospective for a number of minerals including base metals and gold. Licensed mineral exploration has previously been carried out throughout central Tyrone. The area which includes this site is likely to attract further exploration interest in the future. Vegetation and overgrowth of the site is currently at an acceptable level. Any further encroachment of vegetation is likely to obscure key parts of the outcrop and would degrade the value of the site.

Access

Management:

Because this is a very rocky and craggy site it is unlikely that in the future it will come under any direct threat from development.
The site is located within 25m of an occupied dwelling with access limited, at present, to a narrow private lane and the dwelling house yard. Maintenance of this access is likely to be a major management priority.
The rocks of the Tyrone Volcanic Group are considered to be prospective for a number of minerals including base metals and gold. Licensed mineral exploration has previously been carried out throughout central Tyrone. The area which includes this site is likely to attract further exploration interest in the future.
Vegetation and overgrowth of the site is currently at an acceptable level. Any further encroachment of vegetation is likely to obscure key parts of the outcrop and would degrade the value of the site.


Map(s):	GEOLOGICAL SURVEY OF IRELAND, 1877. 1:63,360 Geological Sheet 34 (Pomeroy). Dublin, Ordnance Survey for Geological Survey of Ireland. GEOLOGICAL SURVEY OF IRELAND, 1882. 1:63,360 Geological Sheet 26 (Draperstown). (Dublin, Ordnance Survey for the Geological Survey of Ireland). GEOLOGICAL SURVEY OF NORTHERN IRELAND, 1979. Pomeroy, Northern Ireland Sheet 34. Solid. 1:50,000. (Southampton: Ordnance Survey for the Geological Survey of Northern Ireland). GEOLOGICAL SURVEY OF NORTHERN IRELAND, 1995. Draperstown. Northern Ireland Sheet 26. Solid and Drift Geology. 1:50,000. (Keyworth, Nottingham: British Geological Survey).
Record type:	ESCR report
Entered by:	E M Porter
Last updated:	04 MAR 2001

Enlander, I., Dempster, M. & Doughty, P., 2026. Mveela More, County Tyrone, site details. [In] Earth Science Conservation Review.
https://www.habitas.org.uk/escr/site.php?item=582. Accessed on 2026-11-07.