凿岩

凿岩	záo yán	(rock) drilling
凿	záo	(bound form) chisel / to bore a hole; to chisel; to dig / (literary) certain; authentic; irrefutable / also pr. [zuo4]
岩	yán	cliff / rock
岩	yán	variant of 岩
岩	yán	variant of 岩
岩	yán	variant of 岩