Combined foraminiferal and thecamoebian environmental reconstruction from an isolation basin in NW Scotland: implications for sea level studies

The sedimentary sequence preserved in the isolation basin at Loch nan Corr (NW Scotland) represents a high resolution record of environmental changes over the last 9.5 ka (virtually the entire Holocene). The final isolation of the basin from the sea is recorded over a 6 m sediment sequence lasting c. 7000 years as the rock sill of the basin passes through the intertidal zone. This isolation is due to relative sea-level fall associated with isostatic rebound from the melting of the Last Glacial Maximum ice sheet. Combining faunal counts of foraminifera and thecamoe-bians from the same sample preparations allows an ac-curate reconstruction of sea-level and environmental changes at this site over the Holocene. This study shows the potential for isolation basins in mesotidal areas to provide a series of sea-level index points from a single isolation contact thus improving the ease and accuracy of sea-level reconstructions. Biostratigraphic data im-prove our understanding of the ecology of foraminifera in these relatively unstudied rock-enclosed lagoonal eco-systems. It seems likely that Miliammina fusca can tol-erate the generally low and highly variable salinities in these lagoonal settings more readily than any other fo-raminiferal species