ESCR - Ballyberidagh North Townland lane

Earth Science Conservation Review

Summary Full report
Ballyberidagh North Townland lane - Ballycastle Coalfield	Antrim

Site number:	289	File Number:	D13
ESCC:	EO
Locality Type:	Inland exposure	Status:	ESCR
Grid Reference:	D147388 Centroid
Google maps:	55.18344,-6.19935
County:	Antrim	Council area:	Causeway Coast & Glens Borough Council
Period:	Carboniferous
Stages:	Visean

Site Description
Highlights:
Miospore assemblages containing significant taxa have never been recovered from the lowest strata of the Ballycastle sequence, beneath the lavas and tuffs. New samples collected from outcrops located near the base of the sequence in Ballyberidagh North have however yielded one assemblage that contains abundant, well preserved miospores which are indicative of the Brigantian Stage and the VF Biozone.
Introduction:
None of the boreholes located in the Ballycastle area penetrated through the entire sequence beneath the lavas and tuffs to the basement metamorphic rocks and thus the precise thickness of this 'basal' sequence is not known. These lowest beds are however exposed at localities between Murlough Bay and the Glenshesk River and were sampled at 3 localities, in the Carey River 150m SW of Drumnakeel Bridge (D1598 3976), west of the Glenshesk River in a small river section (D1278 3914) in Drumeeny Townland and in Ballyberidagh North Townland. Four samples from the first two localities were either barren or contained sparse assemblages of non-diagnostic miospores. Location: Exposures of thickly bedded sandstones and thin grey silty sandstones occur in the west-flowing stream located south of Ballyberidagh House. These lithologies were considered to be too coarse and were not sampled. On the north side of the narrow, deeply incised stream valley is a new farm lane that has been cut into the side of the valley in the process revealing two cuttings in which rock is exposed. The easterly cutting exposes grey micaceous carbonaceous silty mudstones and thin dark grey mudstones with thin sandstone beds. Samples from this section contain the miospores. Bibliographic Review: Whitaker and Butterworth processed suitable samples of rock from the lowest beds in the Ballycastle sequence that are exposed at Murlough Bay and west of the Glenshesk River, but failed to obtain any miospores. General Geology: According to the geological maps of the Ballycastle area, the critical exposures in Ballyberidagh North lie stratigraphically below the lavas and tuffs at a level about 50-55m above the unconformable base which is located some 450m south of the stream valley (GSNI, 1963).
Description:
Samples from the locality in Ballyberidagh North Townland have yielded an abundant miospore assemblage that contains the following critical taxa:Dibolisporites distinctus (Clayton) Playford, Grandispora spinosa Hoffmeister, Staplin & Malloy, Murospora margodentata Beju, Schulzospora campyloptera (Waltz) Hoffmeister, Staplin & Malloy, and Speleaotriletes arenaceus Neves and Owens. The presence of M. margodentata indicates that the assemblage is no older than mid-Asbian age. This is based on the subdivision of the NM Biozone into the DP subzone at the base, overlain by the ME subzone with the M referring to the presence, and first appearance in the stratigraphical record, of M. margodentata. The most significant species in the assemblage is undoubtedly Grandispora spinosa which first appears in the succeeding VF Biozone and indicates that the strata at this horizon, only a short distance above the basal unconformity are still Brigantian in age.
Conclusions:
Based on the new biostratigraphical information presented here for the first time, it may be concluded that subsidence of the Ballycastle sedimentary basin commenced in (early?) Brigantian times and extended at least into the Pendleian, in the early Namurian. Indeed there is no evidence whatsoever of basin subsidence having commenced any earlier, for example in the late Asbian, which was a time of basin subsidence and contemporaneous faulting in the SW part of Northern Ireland and elsewhere in the British Isles. At the top of the sequence only evidence for an Arnsbergian age is absolutely equivocal and is discounted at present. It is now apparent that the sedimentary rocks of the Ballycastle area are the only outcropping Carboniferous strata of proven late Vis‚an-early Namurian age that are located north of the Dalradian Highland Border Ridge. Nevertheless there is already a well documented precedent for the onset of basin subsidence in Brigantian times in N. Ireland. The deposition of at least 600m of red-beds of the Greenan Sandstone Formation in a non-marine basin, of precisely the same age as the Ballycastle sequence, occurred on the south side of the Dalradian Sperrin Mountains - Highland Border Ridge, on the north side of the Fintona Block (Mitchell & Owens, 1990). In order to accommodate the rapid influx of over 700m of largely coarse-grained sediment at Ballycastle it is likely that the margin of this basin was a contemporaneous faultline that maintained a consistent, but not excessive topographic contrast between the basin and the land surface to the south. Periodic flooding of the delta top by the sea resulted in the deposition of thin marine horizons but was balanced at times by elevation of that surface, cessation of sediment deposition and development of lush vegetation, peat and eventually, upon burial, coal beds.
Notes:
For information on other sites in Subarea-9 see Key Site 1182 - Subarea-9; Ballycastle.

Keywords
Rocks:	Mudstone, Sand, Sandstone
Fossil Groups:	Miospore
Fossil List:	Grandispora spinosa Hoffmeister, Staplin & Molloy

Access
Approach:	2.8km SE of the confluence of the Carey and Glenshesk rivers.

References (2)
Mitchell, W.I. & Owens, B., 1990. The geology of the western part of the Fintona Block: evolution of Carboniferous basins. Geological Magazine, vol. 127 pt. 5, pp.407-426.
Wilson, H.E. & Robbie, J.A., 1966. Geology of the country around Ballycastle. Memoirs of the Geological Survey Northern Ireland.

Map(s):	GSNI (1963) 1:63,360 Solid Geology of Sheet 8 (Ballycastle).
Record type:	ESCR report
Entered by:	Doughty, P.J.

Enlander, I., Dempster, M. & Doughty, P., 2026. Ballyberidagh North Townland lane - Ballycastle Coalfield, County Antrim, site details. [In] Earth Science Conservation Review.
https://www.habitas.org.uk/escr/site.php?item=289. Accessed on 2026-11-04.