method of flaking. Greywacke was too hard to flake easily and accurately and so bruising the stone with a hammerstone became the main way by which adzes were shaped. The by-product of bruising is a fine powder which cannot be detected in the ground.
Other sites
Other sites, including some which fall into the categories of art and ritual, are difficult to find and interpret. Symbols and stylistic faces carved into the rock in caves or on large boulders represent another dimension to decoration known more widely from portable artefacts and wood carvings. Rock carvings are known from a number of locations: Ongare Point, Whiritoa, Papa Aroha, Coromandel and Kaihere to the west of the Hauraki Plains. At Flaxmill Bay, Whitianga there is a face carved into the rock on the edge of a pool within a stream bed. Obsidian flakes were found within the pool (Law 1966). There are undoubtedly a number of other sites like this that may have had ritual significance.
A different type of site also considered to have ritual or tapu associations was the swamp at Kauri Point. Here a small wooden enclosure had hundreds of broken hair combs made of wood and thousands of obsidian flakes along with many other wooden objects such as spears, musical instruments, gardening tools, wooden containers, plus cordage and gourds (Shawcross 1976). The site is dated to the early 16th century and later.
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