2014 GSA Annual Meeting in Vancouver, British Columbia (19–22 October 2014)

Paper No. 137-7
Presentation Time: 10:30 AM

WHAT SHAPED MT BRANDON? EXAMINING THE RESPECTIVE ROLES OF ANTHROPOGENIC ACTIVITY AND CLIMATE VARIABILITY AS DRIVERS OF LATE HOLOCENE GEOMORPHIC ACTIVITY


ALLEN, Phillip P., Geography, Frostburg State University, 101, Braddock Road, Frostburg, MD 21532, ppallen@frostburg.edu

The combination of environmental factors and cultural activity during the late Holocene has resulted in the familiar landscapes of today. However, uncertainties regarding the roles of climate variability, including extreme events (external forcing) and human activity (land-use change) in initiating and controlling landscape evolution remain. The Dingle Peninsula is the most northerly of the major peninsulas of southwest Ireland, and is characterised by a mountainous terrain that cumulates with Mount Brandon (953 m) adjacent to the Atlantic seaboard. The lowland of the peninsula includes areas of extensive blanket peat and is the location for the majority of the peninsula’s varied and diverse archaeological heritage ranging from the later Mesolithic (c 7000 BC) to the 17th century. Therefore, given its location and cultural heritage, Mount Brandon provides an ideal location for an evaluation of the respective roles of climate variability and anthropogenic activity on landscape evolution. High-resolution geomorphological mapping, sedimentology, vegetation reconstruction via pollen analysis and radiocarbon dating techniques were employed to generate a robust multi-proxy dataset. Geomorphological mapping identified depositional features such as alluvial fans and debris cones and evidence of stream incision indicating phases of varied geomorphic activity throughout the Holocene. Phases of aggradation were radiocarbon dated and when plotted fell into three distinct time periods, 3300 BC-1500 BC, 800 BC to AD 600 and AD 1000 – AD 1800, all of which coincide with well-documented episodes of climate variation and human activity. There is ample evidence of a significant anthropogenic presence on Mount Brandon; however, this signal is complicated by extensive slope readjustment and phases of enhanced fluvial activity. The evidence from Mount Brandon is robust, but it is difficult to clearly identify individual causes of specific episodes of geomorphic activity. Therefore, it is suggested that landscape evolution recorded throughout Mount Brandon is a combination of pre-conditioned paraglacial sediments and the driving influence of a continuum of climate variability and anthropogenic activity.