The Putangirua Pinnacles (officially Pūtangirua Pinnacles, also known colloquially simply as The Pinnacles) are a geological formation and one of New Zealand's best examples of badlands erosion. They consist of a large number of earth pillars or hoodoos located at the head of a valley in the Aorangi Ranges, on the North Island of New Zealand, in the Wellington region.
Some 7 to 9 million years ago when sea levels were much higher, the Aorangi ranges were an island. As this landmass was eroded over time, large alluvial fans formed on its southern shores. Within a few million years however, sea levels rose again and the island was submerged. Since the ice ages, sea levels have receded and the old alluvial fans have been exposed to the erosive forces of wind and water which have weathered away the conglomerate. In some places this conglomerate is protected from erosion by a cap of cemented silt or rock; this has resulted in the formation of spectacular pinnacles, many of which have prominent fluting caused by rainwater running down their sides during major storms. It is not known exactly how long the pinnacles have been forming but they are thought to be less than 125,000 years old; major erosion probably began 7000 years ago and accelerated in the last 1000 years with the deforestation of the area. The current erosion rate is approximately 1 cm per year.
In December 2019, the approved official geographic name of the rocks was gazetted as "Pūtangirua Pinnacles".
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- NZ Department of Conservation Putangirua Pinnacles information page
- Lloyd Homer and Phil Moore,"Reading the Rocks: Aguide to the Geological Features of the Wairarapa Coast", Landscape Publications limited, 1989
- Stevens, Graham Roy (1966). "Putangirua Pinnacles". An Encyclopaedia of New Zealand. Te Ara - the Encyclopedia of New Zealand. Retrieved 25 July 2018.
- Schrader, Ben (11 June 2015). "Wairarapa places - Palliser district". Te Ara - the Encyclopedia of New Zealand. Retrieved 25 July 2018.
- Ian Brodie, "The Lord of the Rings Location Guidebook:Extended Edition", Harper Collins Publishers, 2005
- "NZGB notices – December 2019". Land Information New Zealand. 10 December 2019. Retrieved 15 December 2019.