ashes. Often these marls are richly colored and variegated. In other
places the country rock is a loose sandstone, the disintegration of
which has left broad stretches of drifting sand, white, golden, and
vermilion. Where this sandstone is a conglomerate, a paving of pebbles
has been left,--a mosaic of many colors, polished by the drifting sands
and glistening in the sunlight.

After the canyons, the most remarkable features of the country are the
long lines of cliffs. These are bold escarpments scores or hundreds of
miles in length,--great geographic steps, often hundreds or thousands of
feet in altitude, presenting steep faces of rock, often vertical. Having
climbed one of these steps, you may descend by a gentle, sometimes
imperceptible, slope to the foot of another. They thus present a series
of terraces, the steps of which are well-defined escarpments of rock.
The lateral extension of such a line of cliffs is usually very
irregular; sharp salients are projected on the plains below, and deep
recesses are cut into the terraces above. Intermittent streams coming
down the cliffs have cut many canyons or canyon valleys, by which the
traveler may pass from the plain below to the terrace above. By these
gigantic stairways he may ascend to high plateaus, covered with forests
of pine and fir.

The region is further diversified by short ranges of eruptive mountains.
A vast system of fissures--huge cracks in the rocks to the depths
below--extends across the country. From these crevices floods of lava
have poured, covering mesas and table-lands with sheets of black basalt.
The expiring energies of these volcanic agencies have piled up huge
cinder cones that stand along the fissures, red, brown, and black, naked
of vegetation, and conspicuous landmarks, set as they are in contrast to
the bright, variegated rocks of sedimentary origin.