and the channels are flooded and cut their way again through the
drifting sands to solid rock below. Thus the streams below are
alternately choked and cleared from period to period.

To the south of the Vermilion Cliffs the last series or zone of plateaus
north of the Grand Canyon is found. The summits of these plateaus are of
cherty limestone. In the far west we have the Shiwits Plateau covered
with sheets of lava and volcanic cones; then climbing the Hurricane
Ledge we have the Kanab Plateau, on the southwest portion of which the
Uinkaret Mountains stand--a group of dead volcanoes with many black
cinder cones scattered about. It is interesting to know how these
mountains are formed. The first eruptions of lava were long ago, and
they were poured out upon a surface 2,000 feet or more higher than the
general surface now found. After the first eruptions of coulees the
lands round about were degraded by rains and rivers. Then new eruptions
occurred and additional sheets of lava were poured out; but these came
not through the first channels, but through later ones formed about the
flanks of the elder beds of lava, so that the new sheets are imbricated
or shingled over the old sheets. But the overlap is from below upward.
Then the land was further degraded, and a third set of coulees was
spread still lower down on the flanks, and on these last coulees the
black cinder cones stand. So the foundations of the Uinkaret Mountains
are of limestones, and these foundations are covered with sheets of lava
overlapping from below upward, and the last coulees are decked with
cones.

Still farther east is the Kaibab Plateau, the culminating table-land of
the region. It is covered with a beautiful forest, and in the forest
charming parks are found. Its southern extremity is a portion of the
wall of the Grand Canyon; its western margin is the wall of the West