In the beginning, the main means of production in the mines was open pit mining. To extract the gold bearing ore from the rock, miners drilled holes and loaded charges to blast the rock. When the broken pieces fell to the bottom of the pit, the ore was removed to the mills. The largest and longest-worked of these pits was the Treadwell Glory Hole. Over five million tons of ore was taken to the crushers, leaving a cavernous pit whose dimensions were: Length: 1,700 ft.; Width: 420 ft.; Depth: 450 ft. In 1906, all mining in the area went underground.