Glenroy, a narrow glen 14 m. long, in Inverness-shire, in the Lochaber district; Fort William lies 13 m. NE. of its SW. extremity; the Roy flows through the valley; the steep sides are remarkable for three regular and distinctly-formed shelves or terraces running parallel almost the entire distance of the glen, the heights on either side exactly corresponding; these are now regarded as the margins of a former loch which gradually sank as the barrier of glacial ice which dammed the waters up slowly melted.