Geology and Soils in Deserts of the Southwestern United States - Design with the Desert: Conservation and Sustainable Development - page 35

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Geology and Soils in Deserts of the
Southwest ern United States
William L. Stefanov and Douglas Green
CONTENTS
2.1 Introduction .......................................................................................................................... 37
2.2 Characteristics and Distribution of Deserts .................................................................... 38
2.3 Geological Processes in Deserts ........................................................................................ 39
2.3.1 Fundamental Geological Concepts ....................................................................... 39
2.4 Physiography and General Geological History of Arizona ........................................... 40
2.5 Surficial Weathering Processes .......................................................................................... 43
2.6 Sediment-Transport Processes ........................................................................................... 45
2.7 Desert Landforms ................................................................................................................ 46
2.8 Desert Soils ........................................................................................................................... 49
2.8.1 Climate ...................................................................................................................... 50
2.8.2 Parent Material ......................................................................................................... 50
2.8.3 Organisms ................................................................................................................. 50
2.8.4 Relief .......................................................................................................................... 50
2.8.5 Time ........................................................................................................................... 51
2.8.6 Soil Composition ...................................................................................................... 51
2.8.7 Soil Chemical Properties ........................................................................................ 51
2.8.8 Internal Soil Structure ............................................................................................. 52
2.9 Landscape Organization of Soils ....................................................................................... 53
2.10 Soils of the Built Environment ........................................................................................... 54
2.11 Accessing Geological and Soils Information ................................................................... 55
2.12 Human Impacts on Desert Geology and Soils ................................................................ 56
References ....................................................................................................................................... 56
2.1 Introduction
Deserts are present on every continent and represent the dominant biome in the south-
western portion of the United States. Four major deserts are present within the continental
United States—from north to south, they are the Great Basin (Idaho, Nevada, Oregon, and
Utah); Mojave (Arizona, California, and Nevada); Sonoran (Arizona and California); and
Chihuahuan (Arizona, New Mexico, and Texas) Deserts. 1 This chapter presents a general
introduction to the major geological processes, landforms, and soils typically found in des-
ert environments of the southwestern United States. Our intent is to provide an overview
of those basic geological and soil processes that architects and developers should consider
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