Geological Sciences

Deserts

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Web Links for Parks with Desert Landscapes Bryce Canyon National Park Canyonlands National Park Death Valley National Park Grand Canyon National Park Joshua Tree National Park Zion National Park	Many people believe that deserts are barren, lifeless, and very rugged places. The opposite is true. Deserts are fragile, full of life, and beautiful places to be. This hedgehog cactus is one of many flowers that fill the deserts of the Southwest in the spring.

There is more vegetation in the desert than many people expect and snow may fall in the winter. This photo shows granitic rocks and creosote bushes near Yucca Valley, California.	Some areas are very dry and barren but still beautiful. This is Zabriskie Point in Death Valley National Park. The hills and canyons eroded into the Furnace Creek Formation were cut by water, the dominant agent of erosion in deserts.

Erosion in Furnace Creek carries sediment into Death Valley. Death Valley is a closed basin with no rivers flowing from it to the ocean. Consequently, all sediment that arrives in Death Valley is trapped.	Water washing over rocks in Death Valley will dissolve various salts and carry them to the floor of the valley. Evaporation leaves behind extensive salt deposits. Snow-covered Telescope Peak in the Panamint Mountains lies in the background.

Some areas of Death Valley have mud on the valley floor rather than salt. This photo shows the heavily cracked mud deposits of the Racetrack Playa.	Other areas have sand. These sand dunes in Death Valley are among the most beautiful in California. The Panamint Mountains lie in the background.

Desert landscapes evolve over geological time. Death Valley is youthful with high mountains around it and large alluvial fans at canyon mouths. Note the alluvial fan behind the sand dunes.	This photo was taken from an alluvial fan in the Living Desert Garden near Palm Desert, California. This desert has formed in the rain shadow of the San Jacinto Mountains. The fan forms from sediment discharged from the mouth of the canyon.

This photo, taken in the California Desert near the Little Chuckwalla Mountains, illustrates a more mature desert landscape. The alluvial fans in this area have joined to form an apron of sediment called a bajada.	As desert landscapes mature the mountains remain rough and angular because chemical weathering is very slow in arid regions. Wetter climates result in more chemical and biochemical weathering, thicker soils, and more rounded mountain tops.

Desert pavement forms in arid regions as sand and silt are washed away leaving gravel and cobbles at the surface. Desert pavement takes thousands of years to form. Photo by Howard Wilshire.	This photo shows that a single passage of a dirt bike has severely damaged the desert pavement. Future runoff from rainstorms will be concentrated in this track and accelerate the erosion. Photo by Howard Wilshire.

Dirt biking and other forms of off-highway recreation are very popular in desert regions. The diverse recreational uses for our deserts has become a major management challenge for government agencies. Photo by Howard Wilshire.	Dirt bikes have carved a deep trail into the sandy soil in this area. Vegetation is damaged and wildlife may be killed in these areas. Wind erosion is increased as the vegetation is stripped away. Notice the ripple marks caused by windblown sand. Photo by Howard Wilshire.

Burros left by miners over a hundred years ago have prospered in the deserts of California. They eat the vegetation, damage the soil, and contaminate water supplies driving away native animals. These burros were eventually removed from Death Valley and put up for adoption.	The area that is now Joshua Tree National Park was grazed by cattle in the late 1800's and early 1900's. Ranchers introduced too many cattle and the land was overgrazed and badly damaged. The park is very beautiful today but still not fully recovered from the damage that was done over 100 years ago.

Does Earth Science look interesting to you? Perhaps you would like to major in Geology or Natural Science. Maybe a General Education course in geology would appeal to you. Here are two links that you should explore. Be an Earth Scientist Geology General Education Courses Return to Photo Gallery index page.
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