August 26th - The Geology and Zoology of Whitehead Quarry.


Geology Leader; Bernard Anderson

On Saturday 3rd August 26 members of the BNFC travelled to Whitehead in one of several attempts this summer to recreate an event from the Club’s inaugural year. In keeping with the spirit  of the occasion a majority of those attending travelled by train from Great Victoria Street to arrive in a generally sunny Whitehead at 1.30 pm, 150 years and one day after the visit by the Club’s founder members.  


The excursion on 2nd August 1863 was lead by Ralph Tate. Tate, then a young man of 23, is credited with organising the public meeting in the Ulster Museum on 6th March 1863 which saw the drafting of the BNFC constitution and the election of the founder officers. Tate left Belfast in 1864 to work in London, in South America and ultimately to become the first Professor of Natural History at the University of Adelaide. For more details of an illustrious career, see the Wikipedia article on “Ralph Tate”.


Whitehead Quarry of 1863 worked huge quantities of white limestone (chalk), mainly to supply the local lime-kilns, and also exploited the overlying basalt for the construction of White Harbour, for railway ballast and for road-surfacing. The quarry has not been worked for several decades and it now forms part of a small recreational park. Thick vegetation prevents the visitor from reaching the steep face and so from making a detailed hand-lens examination of the rocks. The black basalt forming the top 10 metres of the quarry face is clearly columnar. Well developed columns are an uncommon feature of the olivine basalts forming the Lower Basalt Formation of the Palaeocene Antrim Lava Group.  The columns at Whitehead certainly do not rival the perfection of the columns in the Middle Basalt Causeway Tholeiites of north Antrim. Surprisingly our predecessors in 1863 were aware that such columns were uncommon so low in the lava succession.




The Lower Basalts in County Antrim typically rest on 0 – 6 metres of bright red “Clay-with-Flints”. Presumably the Clay-with-Flints would once have been visible as a horizontal bright red band in the quarry face, separating the basalts above from the Cretaceous Ulster White Limestone Formation beneath, but grassy vegetation now covers that contact. 


The White Limestone in the lower part of the quarry face is typically well bedded and, also typically, shows numerous bands of flint nodules, each band distinct from its neighbours. Fletcher (1977) was able to demonstrate that the presence and spacing of the individual flint bands, the flint types and characteristics of the individual limestone beds and groups of beds, are remarkably consistent across the entire White Limestone outcrop in Ulster. On this basis he was able to establish an Ulster White Limestone lithostratigraphy of 14 members and map those 14 members over the entire White Limestone outcrop in Counties Antrim, Londonderry, Tyrone and Armagh. Fossils, particularly belemnites, echinoids, sponges and bivalves, are fairly common and demonstrate fairly continuous deposition through the Santonian, Campanian, and Early Maastrichtian Zones of the Late Cretaceous. Fletcher’s Figure 8 “Schematic reconstruction of the spatial relations of the Cretaceous members of Northern Ireland” indicates a thickness of about 38metres for the White Limestone at Whitehead composed of the eight members from the basal Cloghfin Sponge Beds up to the Glenarm Chalk Member (ie. all of the lowest nine members of the fourteen exposed in Northern Ireland).


Curiously the BNFC report of the 1863 excursion says little of interest about the White Limestone – “curiously” because Tate was essentially a stratigrapher and palaeontologist and is credited by Fletcher with “the first major attempt to correlate the faunal sequence of the Cretaceous of Ireland with its counterpart in Britain”. It was Tate (on The correlation of the Cretaceous formations of the north-east of Ireland, Quarterly Journal of the Geological Society of London, Volume 21, 1865) who proposed the name Hibernian Greensand for the formation below the Ulster White Limestone Formation – the name still current for the strata below the White Limestone in Ireland. Clearly the modern BNFC stands on giant’s shoulders!


Leaving the quarry where the upper members of the White Limestone Formation are exposed, the 2013 excursionists walked through the pedestrian underpass beneath the Larne railway line to examine the lowest Limestone members exposed on the sandy foreshore at the western end of Whitehead beach. The basal Cloghfin Sponge Beds Member is only 1.47m thick and consists of three beds: Bed A (“cobbly cemented arenaceous glauconitic limestone"), Bed B (“Evenly bedded arenaceous glauconitic limestone”) and bed C (“Irregularly bedded hard glauconitic limestone”). These are all easily recognised in the Plate 1 photograph of Fletcher’s paper. The outcrop photographed is readily identified near the exit from the railway subway but, sadly since this is essentially the type locality for the Cloghfin Member, Bed C has largely been covered with concrete since it was photographed by Fletcher. The concrete has been used essentially to protect the rock beneath the railway line from marine erosion. We found some sponge pseuodomorphs in the Cloghfin Member and numerous belemnites in the succeeding Galboly, Cloghastucan and Creggan Chalk Members (accounting for some 11 metres of the succession exposed on the beach). 


The party then returned to Whitehead Station and split into two groups. The smaller and more enthusiastic group walked to Black Head to examine the basalts and the excellent pipe amygdales at that locality. It appears that our fit and hardy predecessors on the 1863 excursion walked well beyond Black Head toward the Gobbins! The larger 2013 group were seduced by coffee, tea and a nostalgic train journey on the premises of the Railway Preservation Society in Whitehead.


Bernard Anderson


Essential White Limestone Reference:

Fletcher, T.P. 1977. Lithostratigraphy of the Chalk (Ulster White Limestone Formation) in Northern Ireland. 

Report of the Institute of Geological Sciences, 77/24.


Zoology

We were also lucky with the weather as we recreated the trip to Whitehead by train. At Yorkgate Station a Green-veined White (Pieris napi) was spotted perched on the grass at the side of the tracks.

At Whitehead Quarry were the growth of vegetation makes it almost impassable, we managed to spot 1 Large White (Pieris brassicae), 2 Ringlets (Aphantopus hyperantus), 1 Small White (Pieris rapae), 4 Small Tortoiseshells (Aglais urticae) and 1 Six-spot Burnet (Zygaena filipendulae), a dayflying moth.

As we walked round the area we also spotted some Common Carder bumble bees (Bombus pascorum), White-tailed bumblebees (Bombus lucorum), and Buff-tailed bumblebees (Bombus terrestris).

It would be interesting to compare the sightings 150 years ago however the climate has so much effect on what may be flying and the general flora has changed so much it would not be a fair comparison.

Pamela Thomlinson

 
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Columnar basalt columns at Whitehead Quarry

Small Tortoiseshell (Aglais urticae)

Green Veined White (Pieris napi)

Six spot Burnet

(Zygaena filipendulae)