Curiosity is building towards using its hammer-drill, the last major tool yet to be deployed on the mission.

BBC: Curiosity Mars rover deploys its rock brush

This is positioned on the same tool-turret as the drill, on the end of the robotic arm.

BBC: Curiosity Mars rover spins its rock drill

So, the command was given to drill a second hole that was deep enough to push some cuttings into the tool's sample acquisition chamber.

BBC: Curiosity Mars rover takes historic drill sample