Sediments deposited in arid continental (desert) settings occur throughout much of the rock record. Important depositional environments are alluvial fans, playas (inland sabkhas), and eolian sand seas. Interpretation of the rock record requires knowledge of modern desert processes and environments, yet few sedimentologists or sedimentary geologists have much direct experience in these areas. This book helps to bridge that gap.
Research into geomorphic and sedimentary processes in drylands has expanded dramatically in the past two decades, resulting in many new models and interpretations of well-known landforms, some of which challenge prior interpretations of the rock record. For example, many stone pavement surfaces are now thought to be formed by accretion of eolian dust trapped by the rough surface rather than deflation of mixed particle-size sediment by wind. Phases of alluvial fan aggradation are interpreted as being forced by climatic change, rather than tectonic events. These new views of arid land geomorphic and sedimentary processes have developed as the result of intensive measurement and monitoring of the rates and characteristics of surface processes, coupled with stratigraphic and geomorphic analysis of landforms that show how they have responded to forcing factors.
This book brings together a vast amount of material on desert geomorphic processes and landforms. The thirty chapters involve 34 authors from Britain, Australia, Canada, and the United States and clearly show the dynamic and innovative nature of research into dryland geomorphology. The second edition of Thomas' edited volume is twice the size of the first and has been greatly expanded to include new material (both thematic and synthesizing), as well as revision of older material in the light of ongoing research.
Arid Zone Geomorphology is divided into 6 sections of different length. The first section provides the climatic and tectonic setting for drylands. Section 2 concentrates on surface processes: weathering, soils, crusts (calcrete, silcrete, gypcrete), rock varnish, and the influence of vegetation on erosion and deposition. The third section examines the role of water on slopes, pediments, and in channels and includes chapters on alluvial fans, badlands, and playas, as well as the role of groundwater. Section 4 is devoted to eolian processes, including sediment transport, dunes, dust transport and deposition, and wind erosion. The fifth section of the book is a regional synthesis of the geomorphology of major dry lands. The book ends with a sixth section that includes chapters on the reconstruction of ancient arid settings, with an emphasis on the Quaternary, dating of desert sequences and landforms, human impacts, and extraterrestrial arid environments.
Each chapter is written by one or more experts in the particular field, which lends an authority to the presented material, but also results in some unevenness in treatment of the subject areas, which reflects the writers' experience. In some places, there is duplication of material (e.g. on desert crusts). I found the sections on desert soils and crusts somewhat disappointing, in contrast to the excellent chapters on slope and pediment systems, alluvial fans, river systems, wind erosion, dating of desert sequences, and extraterrestrial arid environments. The regional synthesis chapters are especially useful.
Sedimentologists and sedimentary geologists will find much of interest in this book. The book gives a clear view of the latest developments in this dynamic field. It is up to date, and where there is controversy in interpretations, these are clearly spelled out, and discussed in a balanced way. Many authors conclude with a useful section on what is not known, with suggestions for future research. I found much in this book that was new to me, despite my long involvement in this field.
Arid Zone Geomorphology enters a competitive market, running against new editions of established texts (e.g. Cooke et al., 1993), as well as somewhat similar edited volumes (Abrahams and Parsons, 1993), which incorporate much of the same material (and the same authors in some cases). It scores highly because it is comprehensive, generally well written, and has excellent illustrations. I therefore recommend this book as a general reference for desert geomorphology. It also makes a very good course text for a graduate class on desert environments, or as a recommended reading for a general sedimentary processes course.
References
ABRAHAMS, A.D., AND PARSONS, A.J., 1993, Geomorphology of Desert Environments: London, Chapman and Hall, 674p.
COOKE, R.U., GOUDIE, A.S., AND WARREN, A., 1993, Desert Geomorphology: London, UCL Press, 526 p.
NICHOLAS LANCASTER
Desert Research Institute
Reno
Nevada, USA
Source
http://archives.datapages.com/data/sepm/journals/v66-67/data/068/068005/1054.HTM
Sedimentology and Stratigraphy,SEPM,Sequence Stratigraphy