Midway in the arc of his vision was a ledge, ending in a flat-topped boulder.
The ledge blocked his view, except that he could see trees and a higher peak of rocks beyond it.

He made his way cautiously toward the ledge, his eyes fixed upon the boulder.

A huge, sloping slab of the granite outcropping it seemed, scaly with gray-green fungus in the cracks where moisture longest remained; granite ledge banked with low junipers warped and stunted and tangled with sage.

The longer Casey looked at the boulder, the less he saw that seemed unnatural in a country filled with boulders and outcroppings and stunted vegetation.
But the longer he looked at it, the stronger grew his animal instinct that something was wrong.

He waited for a time--a long time indeed for Casey Ryan to wait.