“They bloom only where it’s always summer,” explained Joe.

That expressed their nature.  They were the orchids of the summer canyons.  They stood up everywhere star-like out of the green.  It was impossible to prevent the mustangs treading them under foot.  And as the canyon deepened, and many little springs added their tiny volume to the brook, every grassy bench was dotted with lilies, like a green sky star-spangled.  And this increasing luxuriance manifested itself in the banks of purple moss and clumps of lavender daisies and great mounds of yellow violets.  The brook was lined by blossoming buck-brush; the rocky corners showed the crimson and magenta of cactus; and there were ledges of green with shining moss that sparkled with little white flowers.  The hum of bees filled the fragrant, dreamy air.

But by and bye, this green and colorful and verdant beauty, the almost level floor of the canyon, the banks of soft earth, the thickets and clumps of cottonwood, the shelving caverns and bulging walls—­these features were gradually lost, and Nonnezoshe began to deepen in bare red and white stone steps.  The walls sheered away from one another, breaking into sections and ledges, and rising higher and higher, and there began to be manifested a dark and solemn concordance with the nature that had created this old rent in the earth.

There was a stretch of miles where steep steps in hard red rock alternated with long levels of round boulders.  Here, one by one, the mustangs went lame and we had to walk.  And we slipped and stumbled along over these loose, treacherous stones.  The hours passed; the toil increased; the progress diminished; one of the mustangs failed and was left.  And all the while the dimensions of Nonnezoshe Boco magnified and its character changed.  It became a thousand-foot walled canyon, leaning, broken, threatening, with great yellow slides blocking passage, with huge sections split off from the main wall, with immense dark and gloomy caverns.  Strangely it had no intersecting canyons.  It jealously guarded its secret.  Its unusual formations of cavern and pillar and half-arch led me to expect any monstrous stone-shape left by avalanche or cataclysm.

Down and down we toiled.  And now the stream-bed was bare of boulders and the banks of earth.  The floods that had rolled down that canyon had here borne away every loose thing.  All the floor, in places, was bare red and white stone, polished, glistening, slippery, affording treacherous foothold.  And the time came when Wetherill abandoned the stream-bed to take to the rock-strewn and cactus-covered ledges above.

The canyon widened ahead into a great ragged iron-lined amphitheater, and then apparently turned abruptly at right angles.  Sunset rimmed the walls.