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at the southern boundary of a large anticline -- the Axial Basin Anticline -- and intervening
<br />synclines. Other well known anticlines in the region include Blue Mountain, Cross Mountain,
<br />and Danforth Hills. Geologically, it began to rise during the Paleocene and separated the Green
<br />River Basin into two parts. Its upward movement was reactivated during the Tertiary and since
<br />then most of the Tertiary -age rocks have been eroded away (Young and Young 1977: 57).
<br />Within the study area the Cretaceous -age sedimentary rocks including sandstones and shales
<br />along with major coal beds of the Williams Fork Formation form the bedrock.
<br />Soils in the general area are numerous (Bulkley silty clay, Clayburn loam, Foidel loam,
<br />Hesperus loam, Hesperus fine sandy loam, Lamphier-Jerry complex, Maudlin-Duffymount
<br />complex, Morapos loam, Torriorthents-Rock outcrop, Ustorthents frigid-Borolls complex, and
<br />Winevada-Spiltro complex), and are found on hills, alluvial fans, plateaus, and/or
<br />mountainsides. These soils are well -drained and generally formed from colluvium and/or
<br />residuum derived from sandstone, shale, loess, and/or sedimentary rocks. Depth ranges from 2
<br />to 60 inches (USDA NRCS 2004). Interestingly, four of the sites occur in more granular loams
<br />including Hesperus and Foidel deposits.
<br />Site elevations range from approximately 7075 to 7650 feet. The dominant vegetation
<br />at these elevations is Transitional Zone brush including oakbrush, serviceberry, and
<br />chokecherry. Grassland/sagebrush openings and parks separate many of the upland wooded
<br />areas. The canyon bottoms have riparian ecosystems with wetland grasses. Aspen encroaches
<br />at the higher elevations and on north slopes. Dogwood, prickly pear, yarrow, mules ears,
<br />manzanita, aster, globe mallow, snap dragons, sego lily, wild pea, saw grass, thistle, Indian
<br />paintbrush, snakeweed, lupine, mint, wild rose, and wild sunflower are also present. Overall,
<br />ground visibility is poor to moderate.
<br />The diversity of habitat in the areas surrounding the sites provides for a variety of
<br />wildlife inhabitants: large and small mammals, waterfowl and other birds, amphibians, reptiles,
<br />and fish. Use of the area is both year round and seasonal; large mammals and waterfowl tend
<br />to migrate to the grassland and riverine environments in the fall and winter, while other
<br />wildlife is present throughout the year. Of the large mammals inhabiting the area, mule deer
<br />and elk are the most numerous and most frequently seen mammals. Grazing the high slopes
<br />and meadows in summer, these ungulates move to lower elevations when the temperatures
<br />drop. Nearly all of the lower slopes (those below about 7300 feet) and terraces flanking the
<br />nearby rivers provide suitable — and often critical — winter range. Although most of the elk and
<br />mule deer populations follow a migration pattern, occasional small groups browse the area
<br />year-round.
<br />During summer most of the elk are high in the thick spruce/fir forests atop the nearby
<br />mountain ranges and in winter they are found on the lower slopes (generally below 9000 feet)
<br />bordering the rivers. It is probable that, prehistorically, both elk and deer summer range
<br />extended below that of present populations, but overgrazing by domestic livestock has depleted
<br />the native grasses such that sufficient lower elevation summer range no longer exists. Other
<br />large mammals present include black bear, and mountain lion.
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