To the Syncline, where we watched a pair of ravens build their nest. Among the braided channels of the arroyo was a beautiful Archaic metate—a smoothly pecked, scooped-out bowl in the bedrock, say two thousand years old.

As we scrambled a rocky side canyon I came upon a desert-varnished boulder with the impression of three ferns, tidy as a museum exhibit. Probably Triassic: more than two million years. Later I went back to look for it. I found the ravens’ nest, but the ferns were lost among the trillion stones of the canyonside.