An introduction to the Quaternary geology and geomorphology of the area around Fort Augustus, Great Glen

Fort Augustus lies within the Great Glen at the south-western end of Loch Ness (Merritt et al., 2013, fig.17). The settlement straddles the Caledonian Canal, which follows the valley of the River Oich south-westwards towards Loch Oich and, eventually, Fort William. The landforms and deposits in the vicinity of Fort Augustus include drift limits, kame-and-kettle topography and raised lake shorelines. They provide important information for interpreting events that occurred during late-glacial times, in particular, evidence for re-depression of the Earth's crust by the build-up of ice in the western Highlands during the Loch Lomond Stadial (LLS) (Firth, 1986, 1989), and for catastrophic drainage of the former ice-dammed lake in Glen Spean and Glen Roy, some 30 km to the south-west, towards the end of the Stadial (Sissons, 1979a, 1981). Three sites are described here; Borlum (NH 384 084), the ‘north shore’ of Loch Ness (NH 386 105) and Auchteraw (NH 364 082) (Fig. 1). A summary of each site is given below together with some new information obtained from a recent geological survey of the district (BGS, 2012). All modern BGS mapping around Fort Augustus is available digitally or as paper maps at the 1:10,000 scale.