Fossil Butte National Park
Visit the home of the Green River Formation and most of my fish by wandering out to Wyoming and stop by The Fossil Butte National Monument.
Location: Fossil Butte National Monument is located in southwest Wyoming near
U.S. Highway 30, approximately 13 miles west of Kemmerer and 15 miles
east of Sage Junction near the Utah/Wyoming state lines.
Elevation: The lowest topographic point in the
monument (where Chicken Creek passes beneath the road a short distance
east of the monument's main entrance) is approximately 6,620 feet above
mean sea level. The highest point is the 8,084 summit of the Bull Pen,
in the northern end of the monument.
Park History and Purpose: The monument was
established in 1972 to protect and preserve a portion of the Green
River and Wasatch formations which contain a unique fossilized
assemblage of organisms that once lived in or around Fossil Lake, an
ancient lake of Eocene age. Many other clues to the environment of
Fossil Lake and its environs are also preserved in the Wasatch and
Green River formations.
General Description: The boundary of the
monument encompasses high, cold desert lands dominated by sagebrush
steppe vegetation. Precipitation averages between 9 and 12 inches per
year; most of it falling as snow. The mean frost-free period is 59
days. Winters can be extremely cold with temperatures occasionally
falling to -30ÂºF or less. Summer nights are cool with the temperature
frequently dropping below 50ÂºF. Summer daytime temperatures rarely
The light-colored strata of the fossil-bearing Green River formation is
exposed on the steep slopes of Fossil Butte, Cundick Ridge, Ruby Point,
and elsewhere throughout Fossil Basin. The Wasatch formation underlies,
overlies, and intermingles with the Green River formation, but, to the
untrained eye, outcroppings of its colorful dull red, pink, lavender,
purple, yellow, and gray strata appear to be scattered at random
throughout the monument.
Small, deep, steep-sided valleys, some named by the monument staff,
dissect the highlands. In the northern end of the monument, the
boundary juts to the west for more than a mile to enclose Ruby Point
and the fossils it contains. Millet Canyon is located on the southern
side of Ruby Point. Murder Hill, Middle, and Moosebones canyons dissect
the eastern side of the monument's highlands. Cundick Ridge is a
narrow, eastern extention of the highland that forms the northeastern
horizon when viewed from the visitor center. The southern side of
Moosebones Canyon is formed by Cundick Ridge.
Fossil Butte, Cundick Ridge, and the Wasatch Saddle form the east side
of the Chicken Creek watershed. Chicken Creek is an interrupted,
intermittent stream with ephemeral tributaries, that drains
approximately 2/3 of the land within the monument. Most of the area
visible from the visitor center back porch lies within the Chicken
Creek watershed. Springs and seeps supply water to the headwaters of
Chicken Creek, but the stream is usually dry for most of its
length, generally flowing only in late winter and early spring with
snow melt, or briefly in response to major storm events.