Forensic cartography with Hochstetter’s 1859 Pink and White Terraces survey: Te Otukapuarangi and Te Tarata

The 1859 field diaries of Ferdinand von Hochstetter (1829–1884) include raw data from a compass survey of Lake Rotomahana. The azimuth array is reverse engineered to identify Hochstetter’s survey baseline. Survey iterations are performed to reconstruct the historic Lake Rotomahana over today’s topographic map. Hochstetter’s papers include a method-of-squares survey map of Lake Rotomahana, providing scale and orientation to the reverse engineered projection. The forensic cartography delivers control points which enabled the authors to georeference Hochstetter’s survey map over the new Lake Rotomahana map. Black Terrace Crater and Te Ariki datum are derived. Validation by waterways, valleys and vegetation lines is undertaken, a biological bathymetry completed and three-point resection performed on the key survey station. The cartography shows the Pink, Black and White Terrace spring locations, Te Otukapuarangi, Te Ngāwhā a Te Tuhi and Te Tarata lie buried on land. From novel lake altimetry the plotted terrace spring locations lie buried 10–15 m. A full archaeological site investigation including imaging and core drilling is indicated to examine the three terrace locations. Excavation on one or more of the Pink, Black and White Terrace sites may then be determined.