Buried treasure dating confirms Maungawhau / Mt Eden Eruption Age

In February 2019, it was reported by City Rail Link (CRL) that their micro tunnel boring machine, “Jeffie”, had become entangled in the remains of an ancient tree while tunnelling beneath the suburb of Mount Eden. Based on information from nearby boreholes, it was determined that the tree was located at a depth of approximately 15 m, and directly below a lava flow from Maungawhau / Mt Eden. During a visit by DEVORA researchers to the CRL offices, several samples of wood from this tree were given for further study and radiocarbon analysis. Examination of these samples by Dr Rod Wallace of the University of Auckland determined that they belonged to two species – A tōtara; and a heavily decayed, unidentifiable, broadleaf angiosperm. Meanwhile, radiocarbon dating of the wood by GNS National Isotope Centre’s Rafter Radiocarbon Laboratory returned an age of 27,970 years before present, with a 304 year margin of error. This aligns with previously obtained ages in placing the eruption of Maungawhau / Mt Eden at approximately 28,000 years ago.

Images provided by City Rail Link


Geocene: Auckland GeoClub Magazine Number 24, December 2020 Cover
Geocene: Auckland GeoClub Magazine Number 24, December 2020

Publication Date: 01/12/2020