30 Shea’s lingering anger at her sister left her reluctant to answer. She stared at the seething flash flood blocking their way. It was too wide to jump and too treacherous to wade. “Look for something we can use for a bridge,” Shea said. Paloverdes, covered in a nest of spiny green branches, hung over the gravy-colored water. Higher up on the bank, mesquites with twisted, gnarled trunks competed with column-like sycamores for space among muddy chunks of granite the size of a motorcycle engine. A sycamore would’ve worked great if they had a way to cut it down—which they didn’t. None of the other trees were suitable for a bridge. Shea used a stick to loosen the dirt around a rock the size of a tire. Her fingers slipped under the edge, lifted up one end, then dropped it with a whomp. It

