178 - The Colyers Island Adze source

Colyers Island exists in the Bluff harbour and was a primary source of argillite for adze manufacture from 1300 -1500.

There are several areas, but the main manufacturing area was on the lower end of the island, near the trees pictured above. This island, and nearby areas, had the best argillite. Even Tiwai Point argillite, not far away across the harbour, was not as usable. Small island outcrops around the area were sourced like below.

The Foveaux Strait region was never permanently inhabited, but exploited by people based in settlements along the Otago coastline. Sources of Bluff and Riverton varieties of argillite for adze manufacture the key factor driving activity in the region. Bluff argillite is a fine-grained, indurated metasedimentary rock forming a part of the Greenhills Group. The material forms as outcrops, water-rolled cobbles, large boulders and ventifacts. Ventifacts are weathered shapes exploited if they had forms similar to an adze shape (see pic on left below).

Very early exploitation of stone sources throughout the entire harbour area, was probably part of a large stone working industry and the distribution confirms its wider importance as a raw material. The Bluff region was not permanently occupied prior to European arrival. Adzes were probably largely finished before they were exported, because the sources could not be readily accessed to replace them. Extensive hammer dressing was an innovation to overcome difficulties working rock. Most hammer stones are made from Gabbronorite or Granite like the one below.

Bluff argillite spread up as far as Kaikoura, revealing there was not any trade outside the south island due to the south islanders being more isolated from the warring tribes that came to the north island later. Polynesians making up the deep south tribes arrived long before Northland tribes.

Two production strategies have been identified in the Bluff Harbour area. Adzes were either made from the careful selection of cobbles with appropriate morphological features (cobble reduction strategy) or adzes were made from thick flakes that were removed from large boulders (flake reduction strategy) as below.

Below is a natural fragmented formation and a solid formation along with a large boulder worked to extract a large portion suitable for an adze.

Tahanga Basalt, Nelson-Marlborough Argillite (Pakohe) and Southland Argillite the most extensively exploited sources for adzes during NZ Archaic period in which the moa was hunted to extinction.

Below is a fine example of a finished product made of Bluff argillite. It makes me wonder what could have been produced now if Europeans had never introduced iron to the Maori. Would the styles have changed, would the workmanship have improved? How intricate would stone tool have become? Considering a distinct lack of quick changes in stone age tools, probably very little. But I still love stone tools more than any other.