A marker pole for embedding in a support medium for drawing attention to potentially hazardous subsurface structures within the support medium includes a generally elongate pole body molded from a generally brightly colored plastic material with a penetrating end formed with a tapered tip for insertion into the support medium, the taper being greater than forty-five degrees from a centerline longitudinal axis of the; and a metal impact cap fitted over the distal end, the impact cap including a generally cylindrical body having an access opening on one end thereof and a substantially planar surface opposing the access opening, the planar surface being in substantial contact with the upper surface of the pole body for enhanced force transmission between the impact cap and the pole body during insertion of the pole into the support medium using an impact producing tool.