How did this Circle come to be Beneath Kauri Forest that pre-dates the Arrival of People to New Zealand

The Cirlcle near the centre of this Satellite Image is beneath Kauri Trees that have been estimated to be older than the accepted arrival of Maori to New Zealand.
This Circle is one of a great many features visible amongst and beneath the last sizeable remant of native Kauri that are up to 2000yrs old.
In the vicinity of Tane Mahuta massive Kauri are aligned in such a way as to suggest they have either been planted in a planned fashion or more likely they are growing on top of Ruins that pre-date any trees or forest in this area.
Other authors and writers have speculated and put forward theories that their has been an advanced culture in New Zealand before the arrival of Maori to New Zealand,HOWEVER nothing I have discovered suggests this.What these discoveries WILL however prove is that there was in Fact a more advanced civilisation flourishing in New Zealand well before the currently accepted timeline for the arrival of the first people to New Zealand.SO who built these structures and what happened to them?
This is the question and it is one that will be hard to answer to the satisfaction of critics of any theory that does not already exist in textbooks.
A trip to Northland's Nelson's Kaihu Kauri, (where a former World Champion Woodchopper Mr Nelson Parker runs a successful business selling Kauri recovered from swamps around the Kaipara area)reveals there has been a massive cataclysm that wiped out vast tracts of Kauri trees and buried them beneath up to 5metres of soil and debris.These Kauri have been Carbon 14 dated to have lived approx 1200yrs ago.Interestingly this is the earliest date put forward in official dating of Maori settlement in New Zealand.
Nelson Parker has logs that have been recovered from areas over 150metres above sea level.
Whatever flattened and buried massive Kauri trees at this altitude would surely have wiped out almost all evidence of any civilisation that may have been in New Zealand.However if only one site exists and I know this one does,then the History of the World will be in need of review.