Environmental changes in Shetland since the end of the last glaciation
The aim of this thesis is to determine changes in the environment of Shetland since the last glaciation. The 'environment' is interpreted in a broad sense, encompassing biotic and abiotic elements and their interactions. This view is reflected in the first section in which existing evidence relating to both the present and the past environment of Shetland is assessed. The form of the last glaciation in Shetland is discussed, the vegetation history since deglaciation is compiled from different sources, and Shetland is seen in the context of general climatic changes in the North Atlantic region since the last glacial maximum. An integrated view of the environment also underlies an appreciation of the need for a new approach to the reconstruction of past environments, or at least an alternative to the conventional interpretation of pollen records. The methodology and application of such an alternative is outlined in the second section of the thesis. The results of the application of this method to the interpretation of organic and inorganic stratigraphy at six lowland sites in Shetland is given in the third section. Sequences of environmental changes are found at all sites based on the interdependent variations in the inorganic sediment, diatoms, and pollen and spores. Suggested correlations of changes between the sites, and with other records, are given in the last section. With the perspective of the background information reviewed earlier, possible causes of the identified environmental changes are discussed. The environment of Shetland during the Lateglacial Interstadial and the 'Loch Lomond' Stadial, the effect of relative changes in sea level, the status of woodland, and the anthropogenic influences during the post glacial period are the main elements in that discussion. Finally, the success of this approach to environmental reconstrion is assessed.