Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6445719 | Quaternary Science Reviews | 2014 | 16 Pages |
Abstract
The chronological challenge of cross-scale analysis within coupled socio-ecological systems can be met with tephrochronology based on numerous well-dated tephra layers. We illustrate this with an enhanced chronology from Skaftártunga, south Iceland that is based on 200 stratigraphic profiles and 2635 individual tephra deposits from 23 different eruptions within the last 1140 years. We present new sediment-accumulation rate based dating of tephra layers from GrÃmsvötn in AD 1432 ± 5 and AD 1457 ± 5. These and other tephras underpin an analysis of land surface stability across multiple scales. The aggregate regional sediment accumulation records suggest a relatively slow rate of land surface change which can be explained by climate and land use change over the period of human occupation of the island (after AD â¼870), but the spatial patterning of change shows that it is more complex, with landscape scale hysteresis and path dependency making the relationship between climate and land surface instability contingent. An alternative steady state of much higher rates of sediment accumulation is seen in areas below 300 m asl after AD â¼870 despite large variations in climate, with two phases of increased erosion, one related to vegetation change (AD 870-1206) and another related to climate (AD 1597-1918). In areas above 300 m asl there is a short lived increase in erosion and related deposition after settlement (AD â¼870-935) and then relatively little additional change to present. Spatial correlation between rates of sediment accumulation at different profiles decreases rapidly after AD â¼935 from â¼4 km to less than 250 m as the landscape becomes more heterogeneous. These new insights are only possible using high-resolution tephrochronology applied spatially across a landscape, an approach that can be applied to the large areas of the Earth's surface affected by the repeated fallout of cm-scale tephra layers.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Geology
Authors
Richard Streeter, Andrew Dugmore,