Two easily transportable drills of Canadian design costing £875 have been intensively operated over a nine-month period and have proved valuable for sampling, stratigraphical control and teaching purposes. A comprehensive range of accessories is available and includes recovery taps, rod spears and core fishers as well as a variety of bits and reaming shells. The more powerful drill will take cores of approximately one inch diameter in successions of mixed sediments to depths greater than 250 ft. Penetration rates, even in hard, compact rocks, usually exceed 1 ft/5 min and average drilling rates of 40 ft/8 h shift for coring at all depths can easily be achieved. Core recovery normally lies between 80 and 85 per cent with the main losses in mudstones and fireclays. Superficial deposits have not presented major difficulties and casing to rockhead at 50 ft is quite feasible. One thousand feet of strata have been drilled at a cost of 3$ 9d per ft, exclusive of any charge for labour, which has been provided by teaching and research staff of the Organic Geochemistry Unit of the Department of Geology, University of Newcastle upon Tyne.
- © 1968 The Geological Society of London