The relation of the Torridon Sandstone to the Moine Gneiss or ‘Eastern Schists’ is one of the primary questions in thegeology of the Scottish Highlands. These two widespread series ofrocks occur on opposite sides of the great overthrusts in North-Western Scotland; and another remarkable feature of their distributionis that though the Torridon Sandstone often rests directly upon theLewisian Gneiss, it never occurs on the Moine Gneiss. The view hastherefore been suggested that the Moine rocks are the easternmetamorphosed continuation of the Torridonian. Some altered Torridon Sandstones certainly resemble the rocks of the Moine Series.Dr. Home, in his address to the British Association in 1901, quotedthe authority of Dr. Teall and Dr. Peach for the resemblance ofaltered Torridon Sandstone to the Moine; and he again remarked thisresemblance in the memoir on the North-West Highlands. The lateW. Gunn went further, and in the same work claimed (p. 612) that “east of Dundonnell good evidence can be adduced that alteredTorridon Sandstone has entered largely into the composition of the Eastern schists”. The recent memoir on the Fannich Mountains represents some of the flaggy granulites of that district as due “to the crushing of Torridonn grit”.