On the cliffs themselves, men suspended on ropes crawled and swung from one spot to another like so many black spiders. Studying them, Joe saw that they were drilling holes in the rock faces with jackhammers. A long, shrill whistle blew, and the jackhammer men scrambled quickly to the tops of their lines. The men with picks and crowbars scurried away from the base of the cliffs. The deep, hollow, concussive sound of an explosion boomed and blossomed across the canyon, reverberating against its rock walls as plumes of white rock dust shot from the face of the western cliffs, and a shower of
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