Particle size and magnetic properties of Holocene estuarine deposits from the Donana National Park (SW Iberia): evidence of gradual and abrupt coastal sedimentation

High resolution particle size and environmental magnetic analyses were carr ied out on two cores from marsh sediments in the Donana National Park (SW S pain), in an investigation of gradual and abrupt coastal change. Complement ary palaeontological analyses were also undertaken. Whilst the balance betw een sea level change and fluvial sediment input is seen to have a strong in fluence on the gradual evolution of the Guadalquivir estuary, via the devel opment and degradation of spit barrier systems, two episodes of abrupt envi ronmental change are recorded by the input of coarser sediment to the hack- barrier These episodes would appear to be associated with high energy condi tions as a result of storm or tsunami events. The multi-disciplinary method ology presented here enables differentiation between these two episodes, th e earlier of which (ca. 2400 yrBP) is probably due to a combination of enha nced erosion potential of the barrier and tsunami activity and the later of which is the result of climatic instability during historical limes (16th- 18th centuries).