A Holocene pollen profile (GRN I) from Garrynagran, north Co. Mayo, Ireland


The sampling site was in an extensive blanket bog, 16 km south of Céide Fields Visitor Centre, where peat cutting had revealed many pine timbers and also oak timbers. This provided the opportunity to carry out a palaeoecological study that included pollen analysis and dendrochronological investigations. In the study area, the bedrock is Carboniferous sandstone which, to the east of the sampling area, gives way to Carboniferous limestone of the Moy valley. Here there are thick glacial deposits including well-developed drumlin fields, and the land is fertile and bogs are few.Core GRN I was taken where what appeared to be an isolated small pine stump (P2/W1) was present at ca. 58 cm in a turf bank (depth from the cutover surface; the uppermost peat (≥1 m) had been removed by peat cutters). At a lower level and in a drainage channel below the peat face, there were several pine timbers. A pine stump P1/W2) at this level from beside the core was 14C dated; pine stump P2 was also 14C dated. The age/depth model (Clam v. 2.2) for the pollen profile derives from a smooth spline curve (smooth factor = 0.4) fitted to ten 14C dates which includes two pine timber dates. The uppermost peat-derived 14C date, 1170±30 BP (10–8 cm; at least 1 m of peat had been removed by peat cutters), was regarded as unrealistically young and was not used.The pollen profile GRN I spans the interval ca. 5700–1800 BC. The pollen profile indicates that pine grew in the mire from the beginning of the record (5700 BC) to at least 2600 BC ('pine flush' recorded at 2700–2600 BC). This is supported by a Pinus stomatal record and also dendrochronological investigations of pine in the extensive bog at Garrynagran.The dendrochronological investigations enabled two floating chronologies to be constructed spanning the intervals 4530-4350 BC and 3135–2700 BC (fixed by 14C dates from dendro-matched pines). These data, together with the pollen data, serve to emphasise the importance of bog-pine in the region at ca. 3000 BC. Profile GRN I shows a distinct Elm Decline (but little P. lanceolata) that is followed by a Neolithic Landnam (3700–3300 BC). After a long lull in activity, farming impact begins to register again in a substantial way in the early Bronze Age (2300 BC). The macrofossil data provide evidence for mire development including a substantial role for Sphagnum austinii from ca. 2750 BC onwards.LOI and tephra investigations were also carried out. A distinct tephra layer was present (9–4 cm; highest tephra concentration at 6–5 cm; ca. 1450 BC based on age/depth model). The results of the tephra investigations have yet to be published.The research, most of which was carried out as a PhD project by Eneda Jennings (1997), was supported by Forbairt/Eolas (Irish Research Council) and NUIG Postgraduate Fellowship scheme.

DOI https://doi.org/10.1594/PANGAEA.912166
Related Identifier https://doi.org/10.1594/PANGAEA.911684
Related Identifier https://doi.org/10.5194/egqsj-69-1-2020
Related Identifier https://store.pangaea.de/Publications/OConnellM_2020/Mayo_GRN1_pollen.xlsx
Metadata Access https://ws.pangaea.de/oai/provider?verb=GetRecord&metadataPrefix=datacite4&identifier=oai:pangaea.de:doi:10.1594/PANGAEA.912166
Creator O'Connell, Michael; Jennings, Eneda
Publisher PANGAEA
Publication Year 2020
Rights Creative Commons Attribution 4.0 International; https://creativecommons.org/licenses/by/4.0/
OpenAccess true
Language English
Resource Type Dataset
Format text/tab-separated-values
Size 3508 data points
Discipline History; Humanities
Spatial Coverage (-9.388 LON, 54.174 LAT)