Rocky

to the Tertiary period of geologic time.
Rocks of almost all types occur including
igneous, sedimentary, and metamorphic clas-
ses. The chief mineral resources are gold,
silver, lead, copper, and coal, and many others
are produced. The immense metallic wealth
discovered in these ranges has been one of

4018 _________________Rocky

leys are called parks, especially in Colorado,
and the bounding mountains are known as
the Park ranges. The Yellowstone National
Park in N. W. Wyoming has been made a
reservation (see YELLOWSTONE NATIONAL
PARK).
Many of the valleys are heavily glaciated,

Rock Temples.
Left, Small temple at Abu Simbel, Nubia; Right, Deir-cl-Bahari, Egypt.

the large factors
prosperity of the
fifty years. This
source of almost
of N. America,
prominent feature,
the outer barriers

in the development and
United States for the past
mountainous region is the
all the large river systems
Erosion is everywhere a
Great canons are cut across
by the main streams, and

and many glaciers, chiefly in Canada and
Alaska, still exist. Many peaks have perpetual
snow. Agriculture is profitable only in the
valleys capable of irrigation, as a rule. But
when governed in this way the soil is ex-
tremely fertile. The higher valleys and moun-
tain slopes are grazing lands of great value.

The Canadian Rockies.
Left, Valley of the Peaks, Laggan, Alberta; Right, Yoho Glacier near Field, B. C.

some of these are among the most noted in
the world. Such is the Grand Canon of the
Colorado, in Arizona and Utah, where al-
most horizontal strata are cut to a mile in
depth by erosion. Picturesque gorges with
falls of great height occur, such as the Yose-
mite in California and the Yellowstone in the
National Park. The high inter-mountain val-

Mining, grazing, lumbering, and farming are
the industries. Lumbering is confined largely
to the Cascade and Coast Ranges. The great-
est forest reserves in the U. S. remain in that
region. The giant sequoias, among the largest
trees in the world, are a product of the Sierra
Nevada and Coast Ranges.
The first formal exploration of the RocMes