During geological mapping by the Institute of Geological Sciences in the Lochaber and Cluanie districts of the West Highlands, mounds of morainic drift retaining a linear structure have been recorded at a number of localities, the largest area of some 50 square miles extending from the mountains south of Glen Kingie [NN 070960] northwards to near Loch Cluanie [NH 100100]. Unlike the lateral morainic terraces seen on some valley sides, the linear structures in question, which are for the most part visible only under favourable lighting conditions or on certain aerial photographs, cross ground with a relief of up to 900 ft, with little deviation in direction. The structures bear no apparent relationship to features of the solid geology such as foliation planes, schistosity, or joints, but are aligned parallel to glacial striae preserved on rare unweathered rock surfaces. Close field examination of lineated terrain, in grid squares [1402] and [1502], north of Glen Garry (Pl. 1, Fig. 1), shows that there is a cover of stony, partly peat-covered drift with numerous locally-derived small boulders resting on a pavement of psammite and granitic rocks. The drift forms low mounds and ridges, 1–3 ft high and 10–100 yd long, the length to breadth ratio commonly varying between 5 and 10. Locally, the mounds form chains up to 200 yd long and 10–15 yd apart. Upslope to the east the drift is associated with large roches moutonnees with ice-quarried faces on their east sides. At a second locality [NH 055108], a little . . .