Department or Program

Geology

Abstract

The Broo Site, located in South Mainland Shetland, is an archaeological site dated to the late 17th century that is believed to have been inhabited for a short period of time before massive sand blows completely buried the stone buildings. Previous investigations indicate deposition of thick sand layers in nearby lochs, potentially tied to Little Ice Age storminess; however the timing and mechanisms of deposition have yet to be determined. Analyses performed on eight cores from the nearby Lochs of Brow and Spiggie include bulk organic matter, stable isotope analysis, biogenic silica, grain size analysis, percent loss on ignition, magnetic susceptibility, and plutonium dating. The objectives of the study were to use sedimentary and geochemical proxies to examine changes in environmental conditions through the last few hundred years. Contiguous coarse-grained sediments were seen in the middle of most cores in the Loch of Brow. Confirmation of a minerogenic layer in the loch was identified through increases in magnetic susceptibility and sediment particle size within the unit, and visual identification. Bulk organic stable isotope analysis indicates a relatively stable carbon isotope signal with δ13C values ranging between -27‰ and -30‰. Stable nitrogen isotope values increased from 1-2‰ at the bottom of the core to 5‰ at the top of the core. Elevated C/N ratios indicate a terrestrial origin of organic matter in organic layers. The proposed models of sand genesis include marine inundation, aeolian deposition, and anthropogenic activity on the landscape, in particular increased agricultural activity, in conjunction with increased storminess of the Little Ice Age.

Level of Access

Open Access

Date of Graduation

Spring 5-2012

Degree Name

Bachelor of Science

Number of Pages

145

Components of Thesis

1 pdf

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