(n.) Drilling. The work shift of a drilling crew that starts in the morning. Drilling operations usually occur around the clock because of the cost to rent a rig. As a result, there are usually two separate crews working twelve-hour tours to keep the operation going. Some companies prefer three eight-hour tours: the daylight tour starts at daylight or 8 AM; the graveyard tour is the overnight shift or the shift that begins at midnight. (Pronounced "tower" in many areas.)See: Drilling Crew, Evening Tour, Graveyard Tour, Tour