Hancox, G.T. 1976 Diamond drilling and the logging of core. Lower Hutt: New Zealand Geological Survey. New Zealand Geological Survey report EG 258 25 p.
Abstract: Despite its relatively high cost, diamond drilling provides the best means of sampling for foundation exploration in rock materials, the greatest single attribute of this method being the ability to core both strong, unweathered rocks and weak weathered rocks and soils; while its adaption to other sampling and testing, such as tube sampling in unconsolidated materials, penetration and permeability testing, offers flexibility while using one machine. Because of the very high standard of core recovery that can be achieved with this method, diamond drilling is now the main method for subsurface investigation for sites for dams, powerhouses, tunnels and quarries. The drilling and logging techniques described below are based on techniques and standards established by the former Snowy Mountains Hydro Electric Authority, especially through the efforts of the late D.G. Moye. These notes and the logging methods now used by the N.Z.G.S., have evolved during the last ten years and further modifications are likely in the future as new techniques are introduced. The principles outlined here, although mainly designed for diamond drilling are also applicable to other types of cored drilling commonly used in conjunction with diamond drilling equipment or as an independent means of investigation. (auth)