A miner operating a Caterpillar D11N Bulldozer in the 002-0 Packer 5 pit was uninjured when a portion of the south ""bottom rock"" highwall unexpectedly failed. The bulldozer was engulfed in the collapse and partially covered by rock and rubble. The bulldozer sustained serious damage and remains in the debris field. The miner exited the bulldozer immediately without assistance.