Palaeoecological investigations at Ballynagilly, a Neolithic and Bronze Age settlement in County Tyrone, Northern Ireland

Abstract

The Neolithic-Bronze Age occupation site at Ballynagilly was covered by blanket peat and surrounded by a deep mire. Stratigraphic investigations, pollen analysis and14C dating were used to investigate the history of the area and to relate this to the prehistoric occupations. A series of14C measurements from the mire were used to establish a deposition rate curve from which a time scale for the vegetational history was derived. This was also used to correlate the vegetation history with14C dated prehistoric occupations. Organic accumulation began in the deep mire about 8000 B.C. (the notation A.D./B.C. is used to denote a conventional14C age less 1950 years) and the earliest blanket peats began forming around 1000 b.c. In the early Littletonian Stage (Postglacial) a juniper phase gave way to birch and willow at *7450 B.C. (* is used to denote a date derived from the deposition rate curve). Until *6050 B.C. there was a period of low water level with a rich mire vegetation. Elm, oak, hazel and pine entered simultaneously at *6050 B.C. creating a dense forest cover. Alder first appeared at *4970 B.C. but did not expand until *3500 B.C. The mid-Postglacial was examined in detail and showed evidence of Neolithic forest clearance involving burning. Charcoal of pine, oak and hazel,14C dated to ca. 3200 B.C. was discovered. This date coincides with those for a Neolithic house and other associated features. The Neolithic clearance phase lasted some hundreds of years with periods of minor forest regeneration. During this phase different types of agriculture may have been used. A total recovery of the forest, albeit with a different composition, was deduced to have taken place before new clearance in Beaker times at ca. 2000 B.C. Somewhat before this, at *2200 B.C., the final decline of pine pollen occurred but was apparently unconnected with human activity. Heath began to develop at *1800 B.C. and increased in extent following Early Bronze Age clearance of scrub woodland at * 1650 B.C. Various clearance episodes from this time through to *200 B.C. caused a further progressive deforestation. Brief regeneration after *200 B.C. was followed by indications of locally wetter conditions and renewed deforestation at A.D. *450. Despite some scrub regeneration around A.D. *800 continuing pressures on the woodland culminated in a open landscape by A.D. *1500.