GEO to U rism California's Death Valley - A Land of Contrast The extremes in landscape that characterize Death Valley National Park yield striking landforms, dramatic and colorful scenery, and underlying geologic mystery. Photo: Tom Smith 66 GEO ExPro December 2007 California's Death Valley - A Land of Contrast Photo: Tom Smith High above North America’s lowest point, salt pans, enormous alluvial fans, and spectacular geology are all seen from Dante’s View. Located in south- eastern Califor- nia, U.S.A., Death Mesquite Sand Dunes located in the center of Valley is easily Death Valley offer tranquility and breathtaking reached by driv- views of the surrounding mountains. Hikers are ing from major regularly seen traversing these dunes, but caution airports serving © USGS is advised due to the hazards of intense heat, sun, southern Califor- and lack of water. nia and Nevada. t GEO ExPro December 2007 67 GEOT O URISM Deborah Bertossa and Thomas N. Smith, Associate Editor Death Valley National Park encompasses 14,000 km² of deserts and mountains, and is the largest outside of Alaska. The Park 11049 feet PANAMINTTelescope RANGE 3368 meters boasts extremes like no other. Badwater Peak Basin, at 86 m below sea level, is the ARCUS RANGE AMARCOSA RANGE AMARCOSA lowest point in the Western Hemisphere PANAMINT VALLEY DESERT DEATH VALLEY not covered by water. Telescope Peak in Sea level -282 feet the Panamint Mountains, at 3,368 m in Backwater -86 meters elevation, lies just 24 km to the west. This vertical drop from Telescope Peak to © USGS Badwater is twice the depth of the Grand A cross sectional view of the Basin and Range topography of Death Valley National Park and surround- ing areas. Canyon and the largest vertical drop in the contiguous 48 states. Death Valley is the hottest, with a record temperature 56.67 °C, and driest place in North America, receiving less than 50 mm of rainfall per year. These factors give the area a forbidding image, yet for the nature or rock lover, the area offers extremes in beauty and fasci- nating geology. Recent Formation Death Valley is the youngest and most active portion of a Basin and Range province that covers most of the southwestern United States and northwestern Mexico. The province is characterized by the formation of steep mountain ranges separated by dry, flat valleys. The northward movement of the Pacific Plate, at about 25 mm per year, is pulling on the North American Plate where Death Valley is situated. This “stretching” of the earth’s surface is pulling apart the North American Plate, fracturing the crust and creating large normal faults and the Photo: Tom Smith “Basin and Range” topography. Most of the Devil’s Golf Course (foreground) is several feet above flood level. Capillary action draws moisture up into the salty crystal structures and is quickly evaporated, leaving a field of salt pinnacles. Snow covered major topographical features seen today Telescope Peak and alluvial fans are pictured in the background. had formed by about 2 million years ago. The Death Valley area is still tectonically active as evidenced by the recent fault scarps in many of the alluvial fans. Volcanism has also played a part in Death Valley's recent geologic history. Extension and thinning of the crust created zones of weakness, usually along faults, that allowed magma from deep within the earth to reach the surface. Aligned volcanic cones can be seen along the bases of the mountains on the west side of the valley. Many areas west of the park in the nearby eastern Sierra Nevada are still considered volcanically active. Photo: Tom Smith The giant Ubehebe Crater field (an Indian name meaning "Big Basket in the Rock") attests to the violent volcanic activity associated with the faulting and stretching of the earth's crust. The eruptions here occurred anywhere from 3,000 to 10,000 years ago. There are over 12 volcanoes in this complex, with Ubehebe being the largest and youngest. The crater itself is 234 m deep and approximately 804 m wide. These explosions stemmed from pressure building up as rising magma mixed with water saturated bed- rock. Immense steam explosions created numerous volcanic craters called maars. 68 GEO ExPro December 2007 Wind and Water Shape the Land Water became a major factor in shaping the landscape as we see it today. During the cooler, wetter conditions of the Pleistocene National Park Service personnel guide geo- ice age (186,000 to 128,000 years ago), large logical tours up the lakes formed in the valleys from runoff of water-polished marble the surrounding mountains. This led to of Mosaic Canyon. The erosion, formation of coalescing alluvial marble originated as limestone laid down fans, and consequent lake sedimentation. when the Death Val- Most notable of these lakes is the prehistoric ley area was covered Lake Manley, once a 180 m deep, 180 km by tropical seas during the Late Precambrian, long lake covering much of Death Valley. then deeply buried and As conditions became warmer and drier, metamorphosed into a Lake Manley receded. Shoreline terraces of "mosaic" of carbonate rocks and marble. the ancient lake can still be seen along the Photo: Tom Smith flanks of the adjacent mountains. Later, during the Holocene (2,000 to 4,000 years ago), wet conditions again Artist's Drive is a one- prevailed and water accumulated in the way, one lane road leading to views of the valley floor. Combining with minerals left Miocene Artist Drive behind from earlier lake deposits, the water Formation. A thick evaporated leaving a shallow briny lake. A section of cemented salt pan is all that remains of these lakes gravel, playa deposits and volcanic debris and now covers more than 518 sq km of is exposed above the the valley floor. road. Chemical weath- Water is also responsible for the ering and hydrothermal numerous alluvial fan formations that can alteration have trans- formed these deposits be seen on all sides of the valley, many with into the beautiful array shallow channels incised on their surface. of colors known as Art- Starting high in the mountains, layers of ist's Palate. Photo: Tom Smith bedrock are gradually broken into blocks. Storms create flash floods that bring these large blocks down the steep mountain sides, gradually breaking them apart. Most of the material is deposited in a chaotic manner in the form of large alluvial fans as debris filled waters slowed onto the valley floors. Death Valley’s recently uplifted mountains expose Precambrian rocks as old as 1.8 billion years to recent deposits. These rocks give evidence of ancient seas, tropical climates, The crudely bedded, mountain building, and volcanism and are chaotic debris of an as diverse as the present day landforms. alluvial fan exposed at Wind also plays its part in Death Valley. Natural Bridge. Photo: Tom Smith Smaller particles of silt and sand grains are picked up by the winds sweeping across the valley creating interesting deposits including sand dunes and prime examples of "desert pavement." The wind working in two ways, both depositing and eroding, have helped form these pavements. Desert pavement consists of tightly packed stones, coated with "desert varnish." Wind shaped A stroll along the salt rocks called ventifacts are also left with pan of Badwater will the "desert varnish", or a wind derived take you to an expanse dark coating of clay, iron, and manganese of dry lake bed com- oxide. Many of the ventifacts display their posed of a salt layer on top of briny mud sand blasted surfaces as pits, flutes, and and the lowest place in Photo: Tom Smith grooves. North America. t GEO ExPro December 2007 69 GEOT O URISM So Much More... In 1881, borax was discovered in the Death Valley playa near what Death Valley is truly a land of extremes. is now the Furnace Creek area. From high temperatures, low rain fall, At that time borax was in high towering mountains and expanses of salt, demand for use as an antiseptic, washing agent, and welding flux. A everywhere you look the contrasts are commercial borax mine operation, unmistakable. Winter can bring snow and Harmony Borax Works, flourished fierce winds; springtime can bring colorful as mule teams were used to haul wildflowers that cover the hills; summer the borax to market. Nearby under- ground springs made living in this soearing temperatures; and fall as a time harsh desert possible and the town to reflect on this dramatic landscape. of Greenland was built (later called Early explorers tried to find riches Furnace Creek). Death Valley was hidden in the surrounding hills. Borax was "put on the map" and in 1933 was declared a National Monument, mined here and prospectors, like Walter and in 1994 gained National Park Scott (Death Valley Scotty), exploited the status. Photo: Tom Smith mysteries of Death Valley to raise money to build his “castle”. Tours of the Spanish styled Scotty's Castle, built in the late was covered by warm tropical seas. Other permit living in this intense climate 1920's and containing priceless antiques interesting sites include Salt Creek where with shady trees, visitor information and and art objects, are conducted year round. the renowned pupfish have adapted to accommodations, a large swimming There are many hikes and drives their very warm and saline environment. pool, and an 18-hole golf course where available that take you through deep- The National Park Service Headquarters sightings of roadrunners and coyotes are sided slot canyons of colorful limestones and Information Center is located at not uncommon. More information on the that were laid down millions of years ago Furnace Creek, a true oasis in the desert.