U. S. Department of the Interior / U. S. Geological Survey
Deserts:
Geology and Resources
by A. S. Walker
Great Sand Dunes National Monument, Colorado (photograph by John Keith).
Beauty is before me
And beauty behind me,
Above and below me hovers the beautiful,
I am surrounded by it,
I am immersed in it.
In my youth I am aware of it,
And in old age
I shall walk quietly
The beautiful trail.
from a Navajo benedictory chant describing the desert
Cacti dominate the Sonoran Desert vegetation near Tucson, Arizona (photograph by Peter Kresan).
What Is a Desert?
Approximately one-third of the Earth’s landsurface is desert, arid land with meagerrainfall that supports only sparse vegetationand a limited population of people andanimals. Deserts—stark, sometimes mysteriousworlds—have been portrayed as fascinating environmentsof adventure and exploration fromnarratives such as that of Lawrence of Arabia tomovies such as “Dune.” These arid regions arecalled deserts because they are dry. They maybe hot, they may be cold. They may be regionsof sand or vast areas of rocks and gravel pepperedwith occasional plants. But deserts arealways dry.
Ripples on a dune in the Gran Desierto, Mexico (photograph by Peter Kresan).
Deserts are natural laboratories in which tostudy the interactions of wind and sometimeswater on the arid surfaces of planets. They containvaluable mineral deposits that were formedin the arid environment or that were exposed byerosion. Because deserts are dry, they are idealplaces for human artifacts and fossils to be preserved.Deserts are also fragile environments.The misuse of these lands is a serious and growingproblem in parts of our world.
DISTRIBUTION OF NON-POLAR ARID LAND (after Meigs, 1953)