The Douglas Street clay occurrence consists of tough, gritty, greyish white, slightly calcareous surface clay. It was used to manufacture brick, tile and flower pots in the first half of the century. The clay is part of the Recent Capilano Sediments which also includes sand, gravel and silt (formerly known as Puyallup Interglacial deposits), (Geological Survey of Canada Map 1553A).

Twenty-eight per cent water is required to work the clay up, giving the resulting mass an air shrinkage of 7.9 per cent. The clay burns to a red colour, which changes to brown at cone 03. The firing tests developed: cone 010, 0.45 per cent fire shrinkage, and 15.61 per cent absorption; cone 03, 8 per cent shrinkage, and 0 per cent absorption; cone 1, fused (Geological Survey of Canada Memoir 24-E, page 149).