Abstract: A drilling assembly which is particularly adapted for drilling in regions of the earth having permafrost, comprising a relativey large earth auger including at least one helical flight which is welded to a long central tube. The upper end of the auger has a shape such that torque may be readily applied to the auger for rotating the same. Interiorly of the upper end of the tube is a means for mounting a downhole percussion hammer, such that the percussion hammer may be suspended for operation within the tube. Preferably, a substantially solid drill bit having a generally frustoconical (pointed) shape is used in conjunction with the percussion hammer. Also, a means for advantageously providing for admitting more compressed air to the bottom of the hole than would normally be admissible by relying on air supplied to the percussion hammer alone.