296 SLATES OF GREAT BRITAIN. there are also quarries at Ingsdon, near Bickington ; East Down, between Ogwell and Ashburton; at Bow, near Staverton; at Tigley and Moor, near Battery; and at Cann Quarry, near Boringdon Park. (d) Lake District. ‘ Westmoreland Slate/ from the Upper Silurian rocks of the neighbourhood of Kendal, of a pale blue and green colour, is much esteemed; similar slates are also quarried at Ulver- stone in North Lancashire. 1 From the Lower Silurian rocks of Skiddaw, sea-green slates are extracted, and shipped from Maryport. (e) Scotland. Owing to the metamorphic condi tion of the Lower Silurian rocks of the Scottish Highlands, they are rarely capable of producing good slates for roofing purposes. The most important quarries are those of Ballachulish in Inverness-shire, and from which from five to seven millions of slates are annually extracted, 2 the weight of which may be estimated at 10,000 tons. The refuse, amounting to five or six times this quantity, is thrown directly into the sea. 3 Slates are also worked at Benledi and Birnam, in Perthshire. The latter quarries yielding about 300,000 roofing slates yearly; also at Craiglea and Drumahern, near Perth; at Dalbeattie, near Dun- keld ; at Glenalmond and Laurick, near Crieff; and 1 Gwilt, Encyc. Arch. p. 522. 2 Ibid. 3 Ibid.