Karen Molloy

Tephrostratigraphy of An Loch Mór, Inis Oírr, western Ireland: implications for Holocene tephrochronology in the northeastern Atlantic region

Twelve definable cryptotephra layers younger than c. 8600cal. BP are reported from lacustrine core material taken from An Loch Mór, Inis Oírr, Aran Islands, western Ireland. The geochemistry of these shard layers, which represent more Holocene tephras than previously geochemically characterized from any European site outside the proximal volcanic influence of Italy or Iceland, is presented. Of these tephras, four may correlate with known Iceland-derived tephra horizons (Vo 1477, HI, Lairg A and H5); one appears to have two possible named correlatives (Hoy;‘Lairg B’ at Sluggan Bog, N Ireland); another has a plausible correlative (AD 860A); but two others represent Icelandic tephras apparently not previously reported on Iceland itself, including a tephra that has geochemistry very similar to Hl (AD 1104) but which dates to c. cal. AD 840. Four tephras that date from the period c. AD 40-1400 have a distinct geochemical signature that relates to Jan Mayen, 750km to the northeast of Iceland and some 1800km distant from An Loch Mór. The results contribute substantially to the chronology of the sediments from An Loch Mór and, at the international level, to the tephrostratigraphy of the northeast Atlantic region. The well-attested Icelandic H4 tephra (from a Hekla eruption of c. 4260cal. BP) was not recorded; it is suggested that An Loch Mór lies south of its recordable distribution in this part of the northeast Atlantic region. Taken together with work at other sites, the findings point to a wealth of potential tephra isochrons in Holocene deposits of the northeast Atlantic seaboard. It is clear also that calcareous lake sediments can be as fruitful a source of tephras as peats. Potential problems relating to dating and geochemical fingerprinting of tephra layers in individual sites are highlighted with reference to the Lairg tephras as recorded in Scotland and Northern Ireland, and to the Hoy tephra that has been described from Orkney.

Holocene vegetation and land-use dynamics in the karstic environment of Inis Oı́rr, Aran Islands, western Ireland: pollen analytical evidence evaluated in light of the archaeological record

Abstract A detailed Holocene pollen record, elaborated in the project TIMECHS, is presented from An Loch Mor, a deep lake at the north-eastern end of Inis Oirr, Aran Islands, western Ireland. Woodland development in the early Holocene is broadly comparable, as regards the general sequence of tree spread and overall woodland composition, to that known from mainland sites in the nearby Burren and Connemara. The main trees in the early Holocene woodlands were Quercus, Pinus and Ulmus. Corylus and a variety of tall shrubs including Betula, Juniperus, Rhamnus catharticus, Ilex, Viburnum opulus and Sorbus had an important role. Taxus expanded and attained dominance for a short period in the later Neolithic and then persisted in small numbers until at least the beginning of the early Medieval period (late 6th century AD). Other notable features included substantial opening-up of woodland cover prior to the Elm Decline, a well-defined Landnam in the early Neolithic (after the Elm Decline), considerable though varying human impact throughout the Bronze Age and continuing into the Iron Age, a distinct regeneration phase that involved regeneration of woody plants—mainly Juniperus, Corylus and Taxus—in the late Iron Age, i.e. the so-called Late Iron Age Lull, and renewed farming activity in the early Medieval period with Secale being introduced in the early 8th century AD. The final demise of woodlands took place between the 13th and the beginning of the 16th centuries though minor amounts of woody vegetation probably persisted on Inis Oirr until at least the late 18th century. The palynological record is discussed in the light of the available archaeological and historical information, and with particular reference to the recently completed archaeological excavations at Dun Aonghasa, the largest stone fort on the Aran Islands.

Palaeoecological investigations towards the reconstruction of woodland and land-use history at Lough Sheeauns, Connemara, western Ireland

Abstract Results of palaeoecological investigations at Lough Sheeauns, a small lake in Connemara, western Ireland, are presented. The main pollen profile spans the period c. 9500 to 1500 B.P. and provides a detailed record of woodland and land-use history. The percentage, concentration and influx pollen diagrams are interpreted in the light of the results from a peat profile taken from near the lake margin and pollen analytical investigations of the recent lake sediment and of peat and peat-covered soils in the region. The rise of Pinus immediately prior to the expansion of Alnus (6700 B.P.) and its subsequent decline are interpreted in terms of low, followed by rising, lake levels. There is evidence for pre-Elm Decline Neolithic activity and, in the immediately post-Elm Decline, an intensive early Neolithic Landnam phase is recorded. It is argued that the Elm Decline is not ascribable to Neolithic activity; an explanation involving disease is favoured. On the basis of results of radiocarbon dating, the early Neolithic Landnam phase is estimated to have lasted 340 calendar years, with intensive pastoral-based farming lasting only c. 150 calendar years. For much of the mid and later Neolithic, palynological evidence for farming is lacking. In the late Neolithic/early Bronze Age (post 4100 B.P.) anthropogenic activity is again registered, at first weakly and then strongly towards the end of the Bronze Age (2900 B.P.). The characteristic lull in human activity known from elsewhere in Ireland is recorded in the late Iron Age (c. 2160 to 1810 B.P.). It is followed by an upsurge in anthropogenic indicators and a reversal in a 14 C date. These changes reflect widespread woodland clearance and intensive farming activity in the catchment which are probably linked with early Christian settlement.

Late holocene human impact on two coastal environments in New South Wales, Australia: a comparison of Aboriginal and European impacts

There are few historical analyses quantifying impacts of human activity in Australia. This paper compares vegetation change, fire regime, erosion and eutrophication rates between the European period and the recent prehistoric past in two lake systems on the south coast of New South Wales. The variance in pollen abundance and hence species population changes increased markedly in the historical period, especially amongst understorey taxa, and this could be related to changes in the local fire regimes and to the effects of grazing. Local fire activity decreased from the prehistorical period at both sites. Erosion rates increased in the historical period and both organic and inorganic components were deposited in the lakes. Erosion episodes could be related to fire during some periods but are clearly controlled by forest disturbance and land-use at other periods. The trophic status of the lakes was increasing from before European settlement but accelerated in the recent past. This was in part due to the increased erosion rates and in part due to fertiliser application. The results suggest that lower rates of erosional and eutrophic change occur in catchments with basaltic than with Holocene sand substrata.

Early land use and vegetation history at Derryinver Hill, Renvyle Peninsula, Co. Galway, Ireland

1. Results are presented of palaeoecological investigations at Derryinver Hill, an important archaeological site in the Renvyle Peninsula, Connemara, western Ireland. 2. Four short radiocarbon-dated pollen diagrams have enabled land-use history on the Hill during late prehistory and the early historical period to be reconstructed in considerable detail. 3. It is shown that pre-bog walls on the Hill — the first to be dated in Connemara — were laid out at 2400 BP, but it was not until 1700 BP that peat accumulation began locally. 4. The evidence indicates that, though grassy heath conditions existed prior to the stone wall construction, peat initiation was retarded through land-use management. When management ceased, the grassy heathland gave way to blanket bog. 5. These findings are discussed in the light of results from a long radiocarbon-dated peat pollen profile from the base of Derryinver Hill and of other palaeoecological investigations in north-western Connemara.

Mid- and late-Holocene environmental change in western Ireland: New evidence from coastal peats and fossil timbers with particular reference to relative sea-level change

The results of radiocarbon dating and dendrochronological investigations of timbers (mainly pine and oak) preserved in coastal peats on the Atlantic coast of mid-western Ireland are reported. These are complemented by the results of pollen analytical investigations, including a detailed pollen profile from Lough Atalia, a brackish lake located within present-day Galway city and immediately to the east of the medieval town. The results from the fossil timber investigations show that pine stumps exposed on coastal intertidal peats in mid-western Ireland date mainly to ca. 3000 BC, that is, they are coeval with the so-called ‘pine flushes’ on blanket bog in western Ireland. Many of the oak timbers are considerably older while an oak on peat in Turlin Bay, near Silverstrand, persisted until ca. 2100 BC. This fossil timber record, taken in conjunction with the pollen records, suggests conditions very different to those pertaining at present, including absence of direct marine influence because of relative sea levels (RSLs) that were probably at least 2 m, and possibly up to 4 m, lower than at present. Mid-Holocene conditions were less stormy, and lower precipitation and/or higher evapotranspiration facilitated tree colonisation of peat surfaces. Intertidal peat layers at Salthill show that present-day RSL began to be approached at ca. AD 500. This agrees with the evidence from An Loch Mór, Inis Oírr, which indicates that salinity in this brackish lake began to increase noticeably at/immediately prior to ca. AD 1000. A notable feature of the pollen record from L. Atalia is a yew (Taxus)-dominated woodland phase of ca. 600 years duration centred on 2550 BC. A major and widespread expansion of yew at about this time is a distinctive feature of mid-Holocene woodlands in western Ireland.

Mid-Late Holocene Vegetational History and Land-Use Dynamics in County Monaghan, Northeastern Ireland—The Palynological Record of Lough Muckno

Abstract We conducted high-resolution palynological analysis on a sediment core obtained from Lough Muckno, County Monaghan, Ireland. The results presented represent the first paleoecological account of Mid-Late Holocene vegetational change and land-use dynamics in the study region. Human activity and agriculture is first recorded during the Early Neolithic (ca. 3870–3500 B.C.). After a period of undiscernible human activity of ∼900 years, farming resumes during the Early Bronze Age (ca. 2600 B.C.). Henceforth, human presence on the landscape is constant with fluctuating levels of intensity. During the Bronze Age, anthropogenic activity is most pronounced during ca. 2000–1750 B.C. and ca. 1500–1300 B.C. followed by a phase of reduced intensity in the Late Bronze Age (ca. 1000–650 B.C.). Farming activity increases during the Iron Age and is disrupted with the onset of a period of rapid woodland regeneration from ca. 200 B.C. to A.D. 200. During the prehistorical period agriculture has a strong focus on pastoral grazing with a limited arable component. An upsurge in agricultural activity is recorded in the historical period from ca. A.D. 400 in which a mixed agricultural economy placing more emphasis on cereal-crop cultivation is adopted. Arable farming attains its maximum levels ca. A.D. 990–1140. Evidence of farming disruptions in the pollen record may reflect of a period of local “conflict” during the Viking Age/Medieval period (ca. A.D. 800–1190). We explore the characterizing features of the pollen assemblage of this large lake system and its use in reconstructing past cultural landscape change.