Geologists have divided the United States into many provinces, each of
which has distinctive geologic and topographic characteristics that set
it apart from the others. One of the most intriguing and scenic of these
is the Colorado Plateaus province, referred to in this report simply as
the Colorado Plateau, or the Plateau. This province, which covers some
150,000 square miles and is not all plateaus, as we shall see, extends
from Rifle, Colo., at the northeast to a little beyond Flagstaff, Ariz.,
at the southwest and from Cedar City, Utah, at the west nearly to
Albuquerque, N. Mex., at the southeast. Canyonlands National Park
appropriately occupies the heart of the Canyon Lands section, one of the
six subdivisions of the Plateau. As the names imply, the Canyon Lands
section of the Plateau comprises a high plateau, generally ranging in
altitude from 5,000 to 7,000 feet, which has been intricately dissected
by literally thousands of canyons.
Canyonlands National Park is drained entirely by the Colorado and Green
Rivers, whose confluence is an important and scenic central feature of
the park (figs. 59, 60). Individual canyons traversed or drained by
these rivers are discussed in later chapters.
When Major Powell reached the confluence in 1869, the river flowing in
from the northeast to join the Green River was called the Grand River,
and the Green and Grand joined there to form the Colorado River. The
Grand River was renamed Colorado River by act of the Colorado State
Legislature approved March 24, 1921, and by act of Congress approved
July 25, 1921. But the old term still remains in names such as Grand
County, Colo., the headwaters region; Grand Valley, a town 16 miles west
of Rifle, Colo.; Grand Valley between Palisade and Mack, Colo.; Grand
Mesa, which towers more than a mile above the Grand and Gunnison River
valleys; Grand Junction, Colo., a city appropriately located at the
confluence of the Grand and Gunnison Rivers; Grand County, Utah, which
the river traverses after entering Utah; and Grand View Point, the
southern terminus of Island in the Sky.
When viewed at a distance of 1 foot, the shaded relief map (fig. 1)
shows the general shape of the land surface in and near Canyonlands
National Park to the same horizontal scale as it would appear to a
person in a spacecraft flying at a height of 250,000 feet, or about 48
miles. This map was prepared by artist John R. Stacy from parts of the
reverse sides of four plastic relief maps[2]—Salina, Moab, Cortez, and
Escalante quadrangles, at a scale of 1:250,000—using a simple time- and
money-saving method he devised (Stacy, 1962).
An image of Canyonlands National Park and vicinity from a satellite at a
height of about 570 miles is shown in figure 7. Note white clouds and
black cloud shadows on right.
[Illustration: CANYONLANDS NATIONAL PARK AND VICINITY, from NASA’s
unmanned Earth Resources Technology Satellite (ERTS-1), at height of
about 570 miles. The space image map was prepared from simultaneous
scanning in three color bands—blue green, red, and near
infrared—that were combined to produce a false-color image in which
vigorous green vegetation (forests and irrigated areas) appears
bright red, water dark blue, and soils and bare rocks various shades
of blue, blue green, or yellow green. Bright-blue area on west bank
of Colorado River about 10 miles southwest of Moab is the group of
large evaporation ponds of Texas Gulf, Inc., shown in figures 31 and
71. Images were taken at 10:31:10 a.m., Aug. 23, 1972, during the
432d orbit, telemetered to Alaska, videotaped, then photographed.
Sun elevation was 53 degrees above horizon from azimuth of 130
degrees. Image covers an area about 100 miles square. (See scale.)
Location of Monticello is approximate; that of other towns is
believed to be correct. Park boundaries are not shown because of
difficulty in locating them accurately, but features such as
Colorado and Green Rivers can easily be compared with those in
figure 1. (Fig. 7).]