A sealing system for a rotary rock bit acts as a barrier to the pulverized cuttings and other materials in the borehole and prevents the materials from entering the bearing area through the cone mouth opening of the cone cutter. The bearing rollers are substantially captured in a groove machined into the cone cutter. This allows a seal unit to be located at a substantial distance from the hostile drilling environment and increases seal life. The shirttail portion of the bit body and the base of the cone cutter cooperate to retard materials in the borehole from contacting the seal unit. The sealing system is provided without reducing the bearing capacity of the bit's bearing system.