gneiss at the bottom and volcanoes at the top.

The Grand Canyon of the Colorado is a canyon composed of many canyons.
It is a composite of thousands, of tens of thousands, of gorges. In like
manner, each wall of the canyon is a composite structure, a wall
composed of many walls, but never a repetition. Every one of these
almost innumerable gorges is a world of beauty in itself. In the Grand
Canyon there are thousands of gorges like that below Niagara Palls, and
there are a thousand Yosemites. Yet all these canyons unite to form one
grand canyon, the most sublime spectacle on the earth. Pluck up Mt.
Washington by the roots to the level of the sea and drop it headfirst
into the Grand Canyon, and the dam will not force its waters over the
walls. Pluck up the Blue Ridge and hurl it into the Grand Canyon, and it
will not fill it.

The carving of the Grand Canyon is the work of rains and rivers. The
vast labyrinth of canyon by which the plateau region drained by the
Colorado is dissected is also the work of waters. Every river has
excavated its own gorge and every creek has excavated its gorge. When a
shower comes in this land, the rills carve canyons--but a little at each
storm; and though storms are far apart and the heavens above are
cloudless for most of the days of the year, still, years are plenty in
the ages, and an intermittent rill called to life by a shower can do
much work in centuries of centuries.

The erosion represented in the canyons, although vast, is but a small
part of the great erosion of the region, for between the cliffs blocks
have been carried away far superior in magnitude to those necessary to
fill the canyons. Probably there is no portion of the whole region from
which there have not been more than a thousand feet degraded, and there
are districts from which more than 30,000 feet of rock have been carried
away. Altogether, there is a district of country more than 200,000
square miles in extent from which on the average more than 6,000 feet
have been eroded. Consider a rock 200,000 square miles in extent and a
mile in thickness, against which the clouds have hurled their storms and
beat it into sands and the rills have carried the sands into the creeks
and the creeks have carried them into the rivers and the Colorado has
carried them into the sea. We think of the mountains as forming clouds
about their brows, but the clouds have formed the mountains. Great
continental blocks are upheaved from be