Nature, chronostratigraphy and origin of late Holocene coastal sands at Portrush, Co. Antrim

Abstract

Detailed analyses of a small exposure in coastal sands at Portrush. Co. Antrim, have yielded data that enable inferences concerning the origin and depositional history of the sands to be made. Site location, elevation, grain-size characteristics, and 14C dating, along with data from a nearby site, combine to suggest that the basal sands at Portrush may result from marine processes during extreme events. The overlying sands are probably aeolian. reworked from the underlying marine sand, and contain buried organic-rich horizons that indicate sand depositional phases alternated with stability phases during which vegetation colonisation and pedogenesis occurred. These data have reinforced recently acquired evidence of a complex pattern of origin and age structure for sands between Portstewart and Portrush that were considered previously as mid-Holocene aeolian deposits. The multi-source, multi-phase depositional history of the Portstewart-Portrush sands has implications for studies of more substantial coastal sand accumulations in which assessment of small-scale spatial variability in stratigraphy, grain-size and pedogenic characteristics may provide evidence for a more complex evolution than hitherto suspected.