of rain or snow on the west slope of the Cascades. The trees
are nourished by this moisture through a long season of annual growth,
and form an evergreen forest which is, in some respects, the most
remarkable in the world. This forest, distinguished by the extraordinary
size and beauty of the trees and by the density of the stand, extends
into the deep valleys of the rivers which have their sources in the
glaciers. On the dividing ridges and in the upper stream basins the
composition and character of the forest change with the increasing
severity of the climate.

The distribution of the different species of trees according to the
intervals of altitude at which they occur separate the forests of the
Mount Rainier National Park into different types. The lines of
separation are to some extent also determined by complex conditions of
slope, exposure, and moisture. The successive forest belts are uniform
in the composition of their central areas, but blend and overlap where
they come together.

The low valleys of the main and west forks of White River, of the
Carbon, the Mowich, the Nisqually, and the Ohanopecosh are covered with
a dense and somber forest of fir, hemlock, and cedar. The trees, pushing
upward for light, are very tall and free from limbs for more than half
their height. Their tops form a continuous cover which the sunshine
rarely penetrates, and on which the light snows of early winter fall and
melt, without reaching the ground. Even in midsummer the light is soft
and shaded, and the air cool and humid. In the wintertime the young
growth is sheltered from wind and the severity of the cold is tempered
by the protecting mountain ranges. Saved from fire by the uniform
dampness of the air the trees grow until they decay and fall from old
age. They are succeeded by the suppressed younger trees. The forest
remains mature, not uniformly sound and vigorous, yet not decreasing as
a whole in size and volume. Individuals perish, but the character of the
forest is constant. The deep alluvial soil covered with moss and decayed
vegetation nourishes a luxuriant tangled undergrowth of vine maple,
willow, and devil's-club. The forest floor is covered with a deep layer
of decayed vegetation and is encumbered with fallen and mossy logs and
upturned stumps. The explorer who leaves the trails must be a strong and
active man if he can carry his pack 6 or 8 miles in a long summer day.

Ascending from the river bottoms to the lowe