Dawson, G.B. 1975 Electrical resistivity surveys in the Purukohukohu experimental basin (southern Rotorua County). [s.l.]: [s.n.]. Report / Geophysics Division 103 21 p.
Abstract: The Purukohukohu Experimental Basin is situated 35 km south of the city of Rotorua on the eastern flank of the Paeroa range. Eight electrical resistivity traverses and three soundings were made in the Purukohukohu Experimental Basin in February and March 1974 and one of the traverses was repeated at closer station intervals in June 1975. The geology of outcrops and dug pits, together with the resistivity surveys, suggests that the general lithology of the area consists of a basement of a nearly impermeable highly porous, saturated, altered montmorillonite tuff varying in depth from outcrops at the surface to 54 m, with resistivities varying from 57 to 11 ohm-metres. The tuff is mostly covered by saturated gritty clays with resistivities from 230 to 250 ohm-metres, then a layer of permeable pumice breccias and sands with resistivities from 2000 to 2600 ohm-metres. This is covered in some cases by layers of various soils, the resistivities of which vary from 350 to 1800 ohm-metres. The ground water, which appears as springs in the basin, was observed, in an inspection pit, to flow along the interface between the saturated gritty clays and the pumice breccia (auth.)