The Duncan Clay occurrence is composed of Recent clays of the Capilano Sediments (formerly known as Puyallup Interglacial deposits). The clays of this type are described as being somewhat sandy and yellowish to bluish grey in colour and in most places contain fairly abundant pebbles. The clay is fairly plastic, dries with moderate shrinkage and burns hard and red at low temperature. A sample of this surficial clay contained 67.6 per cent silica, 13.6 per cent alumina, 8.8 per cent iron oxide, 3.6 per cent lime, 0.2 per cent magnesia and 5.6 per cent water and loss upon ignition (Geolog- ical Survey of Canada Bulletin 96, page 308).

These clays are suitable for the manufacture of common brick and drain-tile, and for the manufacture of portland cement. Prior to 1917, bricks were made from this material at Somenos. No production figures are available.