Bill Knox (right) at a site at Tautuku. Photo: Supplied

Shaped stone blocks found at Tautuku in South Otago, the Catlins, and Stewart Island, support the theory early Maori settlers sailed direct from Tahiti over 4000km of open water.

Heritage New Zealand said today the geochemical signatures of the three shaped scoria blocks found in three early Maori occupation sites have the potential to challenge understanding of prehistoric human settlement in New Zealand.

The findings have come from research by retired geologist Dr Ross Ramsay of Kerikeri, and research colleagues Graeme Collett of Dunedin, Georgia Kerby of Whangarei, and consultant Gael Ramsay.

Tautuku scoria stones. Photo: Supplied

The four have recently completed geochemical testing of what they believe are likely to be three marae stones brought to New Zealand by some of the earliest east Polynesian settlers from their ancestral home in the Hawaiki zone.

It appeared the early navigators placed the scoria blocks, or marae stones, at different points of their arrival in the southern South Island.

The petrographical and geochemical signature of the three blocks was closely comparable one with the other, and to a similar stone brought back from Tahiti by former Otago Museum director H.D. Skinner in the early 1930s.

"The three South Island blocks were found at different times over a period of close to fifty years; two of them excavated from archaeological sites that also contained east Polynesian-style artefacts and the remains of the extinct moa.

"The third one was found on a sand dune in Stewart Island with eroding Maori cultural material very close by,'' Dr Ramsay said.

The first scoria block was discovered in January 1939 by archaeologists David Teviotdale and Les Lockerbie in the Catlins, and the second by Lockerbie and Bill Knox in the early 1960s in an excavation at Tautuku in South Otago.

"Given the archaeological context in which these scoria blocks were found _ and the distinctive nature of their geological composition exotic to New Zealand _ it now appears likely that all three blocks were brought here hundreds of years ago by the first Polynesian settlers,'' he said.

Heritage New Zealand pouhere taonga Northland manager Bill Edwards said the findings supported the idea the objects were brought here from Polynesia by people many hundreds of years ago.

Mehetia Island. Photo: Supplied

Now the most likely source of these blocks had been identified, they posed more questions, and provide evidence of the remarkable navigation skills of the people who brought the rocks with them to New Zealand.

Dr Ramsay said: "It's possible that the people who arrived here sailed direct from Tahiti over 4000km of open water _ a distance comparable from Tahiti to Hawaii _ following the patterns of migratory birds rather than `island hopping' through the Tonga-Kermadec arc and then fanning out around the North Island as other waka did.''

"If that's the case then we're talking about navigators with extraordinary ability.

"The fact that they left their homeland with scoria blocks is also an indicator that they fully expected to arrive at a destination.''