last ice sheet

moraines

till

glacial erratic

Glaciation of Westray

Glacial stratigraphy

On the main tools for reconstructing the glacial history of an area is to examine the local stratigraphic record. Tills are firm indicators of the former presence of glacier ice and their fabrics and erratic content provide information about the direction of former ice movement. Where tills are inter-bedded with other sediments, such as meltwater or periglacial deposits then a sequence of events can be built up.

On Orkney, the possibilities for the development of complex stratigraphy has been greatly reduced by the erosive effects of successive ice masses. The latest glaciers tend to erode the loose sediment deposited by earlier ice masses and meltwater. Nonetheless useful information can be provided even when only two tills are superposed at sites such at Denwick and Scara Taing.