Farming and woodland dynamics in north Sligo during the Holocene based on lake-sediment investigations

Detailed pollen-analytical investigations were carried out on lake sediment cores from two lakes, namely Lough Dargan and Cooney Lough, in north County Sligo close to the Cúil Irra peninsula. North Sligo was chosen as a study area on account of the wealth of archaeological evidence relating especially to the Neolithic, i.e. first farming peoples. Cúil Irra peninsula is particularly rich. It has the largest passage tomb cemetery of Ireland, namely Carrowmore and also the archaeologically rich and conspicuous mountain, Knocknarea. Evidence for early Neolithic activity includes Magheraboy causewayed enclosure that is possibly the earliest Neolithic causewayed enclosure known from Britain and Ireland. The investigations reported on here reconstruct early farming activity, woodland dynamics and the land-use, based mainly on detailed pollen analysis. Macrofossils analysis, magnetic susceptibility and loss-on-ignition measurements were also carried out. Age/depths models for the pollen profiles were constructed on the basis of the results from AMS radiocarbon dates. Attention has also been paid to early Holocene climate change, and human impact and woodland history in the later post-glacial (Bronze Age to recent times). From L. Dargan, east of Ballygawley, parallel cores of ca. 7.5 m were collected. Most of the main core (DRG1) was pollen analytically investigated. The resulting pollen profile spanned the interval ca. 7800 BC-AD 1700. From Cooney L., west of Ballysadare, parallel cores were also taken. A pollen profile, based mainly on the 6 m long core CNY1, spanned the interval ca. 7450-790 BC, i.e. most of the early and mid Holocene. The results from the two high-resolution pollen diagrams show that tall canopy woodland characterized the first half of the Holocene. There is little or no evidence for human impact on the primeval woodlands but there are clear pointers, especially in the pollen profile CNY1, for climate anomalies in the early Holocene. The main anomaly (CA-3) is regarded as corresponding to the 8.2 ka event as known mainly for Greenland ice-core records. This is the first securely dated, published record for the 8.2 ka event in Irish or British pollen records. A well defined Elm Decline is recorded in both profiles. The earliest indication of farming (cereal growing) in both profiles coincides with the Elm Decline (ca. 3750 BC). After a delay of some decades, a distinct Landnam is recorded in both profiles that involved woodland clearance by early Neolithic farmers. Landnam at L. Dargan lasted from ca. 3700¿3000 BC and was considerably longer than at Cooney L. where it had largely ceased by ca. 3400 BC. At both sites there appears to have been little or no activity in the mid Neolithic (ca. 3000 BC) but by 2700 BC farming impact again registers but the impact is not as high as during the main Landnam. Neolithic farming was mainly pastoral based but there is clear evidence for cereal growing at both sites. Major human impact registers again at ca. 2150 BC in both profiles. This is regarded as reflecting early Bronze Age impact that involved both pastoral and arable farming. Three main farming phases are recorded in both profiles. These are associated with a strong increase in micro-charcoal, mainly in the DRG1 profile. In both profiles, the strongest impact registers in the late Bronze Age (ca. 1000 BC) but that in CNY1 is of shorter duration. Profile DRG1 records developments in the Iron Age and the historical period (to ca. AD 1700), including woodland and farming dynamics. A distinct lull in pastoral farming is recorded in the late Iron Age (ca. 80 BC-AD 350) that facilitated limited woodland regeneration. This is regarded as the Late Iron Age Lull. Substantial woodland clearance, and farming that included a considerable arable component, characterised the Medieval and later periods. The results obtained in the course of these investigations are discussed in the context of palaeoecological investigations carried out by others in Co. Sligo and in western Ireland generally.2017-02-2