rock. And so it kept on
until it had carved a passage not only to the original granite bed rock
but in places a thousand feet or more into it. A few localities
excepted, the canyon does not form a single gash; nor has it the usual
V-shape of canyons in regions of plentiful rainfall. On the contrary,
its cross-section takes the form of a succession of steps and terraces,
as though the river cut the channels successively in decreasing widths.
And because the region through which it flows is one of very slight
rainfall, all the landscape outlines are bold and sharply angular.

All told, an area comprising two hundred thousand square miles has been
denuded to the depth of six hundred feet, and the material borne
southward by the Colorado and its tributaries, while the land through
which they flow has been literally drained to death. Even the
tributaries have formed deep lateral canyons that meet the level of the
main stream. It staggers the mind to try to grasp the time expressed in
countless eons since the youth of this now senile river.

[Illustration: The Grand Canyon of the Colorado]

As early as 1540 Spanish explorers made known to the world the fact that
a deep and impassable gorge existed in one part of the Colorado River,
and again in 1776 a Spanish priest revived a knowledge of its existence.

Then, for many years afterward, the canyon claimed but little attention
because it was so difficult of access, and so little was known of its
colossal dimensions and the marvellous carvings within its walls.

Just above the Grand Canyon and continuous with it is Marble Canyon, so
called because of the immense beds of marble that form a part of its
walls. In both canyons the limestone sometimes takes the form of marble,
or gypsum, or alabaster--crystallized forms of limestone which take a
fine polish.

This remarkable river with its canyons was first explored by Major
Powell in 1869. With nine men and four boats he started from a landing
on Green River in Utah, floated down Green River to its junction with
the Grand, and thence down the Colorado below the mouth of the Virgin to
the Grand Wash. There he landed after having passed through the entire
length of the canyon.

The time spent in this voyage was ninety-eight days, and the distance
travelled was upward of one thousand miles. Four of his men left him
when the voyage was but partly finished, being frightened by the perils
that beset them. They were killed by India