On our last trip, we brought ropes and went down the first waterfall forty vertical feet, only to be confronted by a second, sixty-foot-high, overhanging waterfall that emptied into a slot canyon.

“Much of the ground where Ms. Hollingshead found her diamond is made of unweathered volcanic rock. When it rains, flowing runoff often leaves loose gravel, and sometimes diamonds, on the surface in these areas.”