Laughlin Tour 1 Las Vegas to Laughlin Northern Basin & Range Region USDA MLRA Office #3 Douglas J. Merkler - Soil Scientist January 2002 A roadside tour to Laughlin Las Vegas Valley Fastest growing urban area in the United States After maneuvering though the urban sprawl of Las Vegas and Henderson you will be headed south along Las Vegas Valley is one of the fastest growing population Highway 95. As you leave Henderson and Las Vegas centers in the United States. Las Vegas Valley covers an Valley behind, you will begin to climb a small grade, our area approximately 350 square miles in the southern first point of interest. Somewhere just before you reach portion of Nevada. The lofty Spring Mountain Range rises the summit reset your trip odometer, the tour begins…. to 11,918 feet at Charleston Peak and provides significant vertical relief as the western boundary of the valley. This is reflected in the rapid gradient of soil temperature and Railroad Pass – mile 0 – 2,385 feet moisture regimes. From thermic to cryic, from aridic to xeric, the rapid rise in topography controls the factors of soil formation. Las Vegas Valley is boxed in typical Basin and Range fashion to the north by the Sheep and Las Vegas Ranges reaching 9,756 feet; to the east by Frenchman Mountain; and on the south by the River and McCullough Ranges. Although outside the hydrological definition of the Great Basin (Las Vegas Valley drains into Lake Mead and the Colorado River by Las Vegas Wash and its system of tributaries), it typifies the biologic, pedologic, physiographic and geologic complexity of the Great Basin. continued on page 2 I NSIDE 1 Las Vegas Valley - page 2 2 Roadside tour – pages 2 through 8 3 Suggested Reading – page 8 Landsat image of the Las Vegas Valley and the 11,918 ft. Charleston Peak in the adjacent Spring Mountain Range. 4 Overview Map – page 1 Laughlin Tour 2 continued from page 2 gap in the River mountains to carry gravel and aggregate to the Hoover Dam job site. The Pass At our first point of interest the soils on the hill and started out as just another squatters’ camp in the early mountain slopes are loamy-skeletal, mixed, days of the Hoover Dam construction, but its character superactive, calcareous, thermic, Lithic Torriorthents. changed overnight when an enterprising promoter The fan remnants are well developed loamy-skeletal, arrived on the scene and built a casino almost within mixed, thermic, Typic Haplocalcids dissected by eyesight of the Boulder City township boundary. channels of rarely flooded, sandy-skeletal, mixed Interestingly, the first load of building materials (calcareous), Typic Torriorthents. delivered by the Union Pacific when the branch line The vegetation is dominated by two of the most from Bracken to Boulder City opened late January, abundant plants of the Southwest deserts, creosote- 1931, was used not for construction of the dam or dam bush and white bursage. The leaves of the workers’ community but to erect the Railroad Pass creosotebush glisten as if freshly wet, because of a Club. coating of oily resin. This oil adaptation protects the You will take the next exit to Searchlight just past the plant from too great a water loss during long, dry Railroad Pass Casino…heading south into Eldorado periods between rains. Lac, a resinous incrustation on Valley… the branches, was used by Indians to repair pottery and glue arrowheads to arrow shafts. White bursage Northern Eldorado Valley – mile 5.8 – 1,750 feet As you head south on highway 95 you are descending along a fan piedmont into the bolson of Eldorado Valley. As the gradient begins to level out on the alluvial flat a change in vegetation and soils become apparent. Here the salts begin to surface Creosotebush White bursage is often found in association with creosotebush and handles the dry periods quite differently. Only during the spring are its leaves green. As summer heat arrives the leaves lose their color, become ashy-white and the entire plant appears to be dead or dying. In spite of a bitter taste, it is one of the important foods of the desert bighorn sheep and other animals. Cattle saltbush as snow-white efflorescent crusts, pulled to the surface by an 80 inch a year evapotranspiration gradient of the dry desert air. The soils are fine-loamy, mixed, superactive, thermic Typic Natrargids and coarse- loamy, mixed, superactive, thermic Typic Haplocalcids on the alluvial flats with sandy, mixed, thermic, Typic Torriorthents on slightly higher elevation eolian influenced fan skirts. The plant community expresses a preference for salt tolerant species such as the cattle saltbush present at this location. Surface water from atmospheric source descends the drainage ways and collects in the basin. Loss of water is only through evaporation, transpiration by plants and subsurface Railroad Pass was named for the crest of the grade percolation to groundwater. Sediment is trapped in the where the Union Pacific line passes through a broad basin, and except for what may be blown away by Laughlin Tour 3 continued from page 3 mixed, superactive, thermic, Typic Haplargids formed wind, the entire sediment record is preserved in the in the alluvium from the Precambrian gneiss and schist basin as a playa… of the Eldorado Mountains. Gold was discovered in the area of Eldorado Canyon in 1857 (some say 1861) making it one of the oldest mining districts in Nevada. Eldorado Valley playa – mile 7.3 – 1,733 feet The term Eldorado was applied to regions to signify gold and fabulous riches. The Army, in a mistake, established Camp Eldorado on the north side of Eldorado Canyon to protect the miners and steamboat traffic on the Colorado River. When the Army arrived there in January 1867, there were only three white men in the area, no steamships were running and the few Indians that were there were in no condition to fight. Nelson's landing (on the river below the townsite) is noted for washing into the Colorado River in 1974 after a strong downpour in the mountains sent the runoff down the channels and produced a flash flood. There are five wide channels that run from the mountains toward the river. Unfortunately, they converge into a small outlet where Nelson's Landing was located. The entire landing and village was destroyed and nine people lost their lives when the flood came through the Here even the toughest, most salt tolerant plant wash. The wall of water and debris was reported to be species throw in the towel, with only a few clumps of 40 feet high as it reached the river. pickelweed growing near the edge. The mountains in the distance to the west are the Southern Eldorado Valley – mile 24.1 – 2,795 feet northern extent of the McClullough Range; to the east, the Eldorado Mountains flank the Colorado River for 23 miles to Eldorado Canyon at Nelson. Loamy- skeletal, mixed, superactive, calcareous, thermic, Lithic Torriorthents dominate the lower slopes with loamy-skeletal, mixed, superactive, calcareous, thermic, shallow Typic Torriorthents on the higher elevation mountain slopes where cooler temperatures and higher moisture allow for the weathering of the bedrock… Nelson turn off – mile 12.0 – 1,838 feet Just before you begin a gentle turn to the southeast the highway comes close to the large drainageway that defines the axis of the southern end of Eldorado Valley. Here, a slight increase in production is noted with the addition of big galleta (a perennial grass) and mojave yucca to the familiar creosotebush and white bursage along the east side of the valley. These are relatively young surfaces with sandy-skeletal, mixed, calcareous, thermic, Typic Torriorthents within broad inset fans and fine-loamy, mixed, superactive, thermic, Typic Haplargids with weakly developed argillic horizons on fan summits. Within the drainageway Here the fan piedmont is dominated by coarse-loamy, flooded phases of sandy-skeletal, mixed, calcareous, Laughlin Tour 4 continued from page 4 thermic Typic Torriorthents support a larger distinct Searchlight hills – mile 35.1 – 3,717 feet shrub. Numerous thorns, short and curved like a cat’s claw, readily identify the deciduous shrub as catclaw. The plant is heartily cursed by the rider and hiker alike because of its ability to catch and tear clothes and flesh. The thorny branches offer an excellent nesting site for birds and the lower branches afford fine protection for small mammals. Catclaw Big galleta As you approach the low hills of Searchlight, loamy- In contrast, on the west side of the drainageway the skeletal, mixed, superactive, thermic Lithic Haplargids surface is older and well developed. Here loamy- carry a unique plant community. Here you will observe skeletal, mixed, superactive, thermic, shallow Typic blackbrush beginning to dominate the landscape in a Haplodurids provide an inadequate water supply ecotonal transition from the hot deserts to the cooler capacity to support the catclaw and grasses… wetter communities of the Great Basin. Although many herbaceous species occur in the blackbrush communities, they are seldom present in large numbers. Disturbed blackbrush rarely re-establishes. Almost to Searchlight – mile 32.0 – 3,385 feet It is thought that between about 19,000 and 12,000 years ago, woodlands composed of juniper and single leaf piñon were widespread throughout the Mojave Desert, from elevations as low as 2,000 feet to those as high as 6,000 feet. As these communities retreated as a result of the late Pleistocene climatic change blackbrush became established in what is now the ecotone between the thermic and mesic zones of the Basin and Range. Some of the older surfaces in the desert will have almost a 100 percent cover of rock fragments.