A Physical and Mineralogical Analysis of Late Holocene Sand Deposits: A Case Study of Little Ice Age Coastal Change in the Shetland Islands, UK
Late Holocene climate fluctuations resulted in pronounced coastal change across the North Atlantic. The transition between the stable Medieval Warm Period and the stormy Little Ice Age was associated with an increased north-south thermal gradient that led to a southward displacement of the polar atm...
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SCARAB
2014
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| Online Access: | https://scarab.bates.edu/geology_theses/71 https://scarab.bates.edu/context/geology_theses/article/1073/viewcontent/CHalstedThesis.pdf |
| Summary: | Late Holocene climate fluctuations resulted in pronounced coastal change across the North Atlantic. The transition between the stable Medieval Warm Period and the stormy Little Ice Age was associated with an increased north-south thermal gradient that led to a southward displacement of the polar atmospheric front and polar waters. The increased frequency and intensity of storms during the LIA resulted in inland sand transgressions that displaced communities across Europe and altered coastlines in the process. A case study of this coastal change can be observed in the southern Shetland Islands, where extensive, thick deposits of sand stretch far inland. Within these sands are the buried remains of the township of Broo, which was abandoned in the midst of total inundation in the mid-18th century (Bigelow et al. 2005). The nearby Loch of Brow contains a distinctive, fine sand unit that has been hypothesized to be a result of the sand invasion event(s) that buried the township of Broo. Also within the study area are the Bay of Scousburgh and the Loch of Spiggie. 17th century maps show an inlet connecting the Loch of Spiggie to the ocean through the Bay of Scousburgh, but presently there is a low-lying land bridge separating the two. It has been hypothesized that the land bridge, as well as a sand unit found in the Loch of Spiggie, were created during a period of intense storminess within the LIA. In order to test the hypotheses presented, sand samples were collected from around the study area and subjected to x-ray diffraction, grain size analysis, and grain surface morphology. XRD results established a mineralogic relationship between the Loch of Spiggie and the Bay of Scousburgh. These sites shared peaks in their diffractions that were missing in the Quendale sites and the Loch of Brow, simultaneously establishing a potential relationship between these sites as well. A trend of decreasing grain size and increasing sorting was observed between the Bay of Quendale and the Loch of Brow, suggesting a fining of ... |
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