Then, just when he was mentally debating an impulse to climb to the top of the gully, to see if the rider was in sight, he heard a sound as of a heavy body crashing through some underbrush, and saw two riders skirting the edge of the arroyo near him.
They halted their horses back of the spruce trees near the arroyo edge.
The rank undergrowth in the timber prevented them seeing Sanderson's horse--which was further concealed by the thicket of alder.

The men, however, did not look into the arroyo.

Their attention and interest appeared to be centered upon the actions of the first horseman.

Sitting erect in their saddles, they shaded their eyes with their hands and gazed northward.
After a short look, one of the men laughed, unpleasantly.
"Sneakin'-- he is," said the one who laughed.

"Knows we're campin' on his trail, an' reckons on givin' us the slip.