Chapter 5 Soil and rock description and characteristics
Published:January 01, 2012
M. Stokes, J. Charman, R. J. Epps, J. S. Griffiths, Engineering Group Working Party, 2012. "Chapter 5 Soil and rock description and characteristics", Hot Deserts: Engineering, Geology and Geomorphology Engineering Group Working Party Report, M. J. Walker
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Hot desert soils and rocks possess a number of distinct characteristics that relate to:
desert rock weathering and disintegration processes;
modes of desert soil transport;
desert pedogenesis and post-depositional modification/cementation.
Rock weathering, disintegration and soil formation under arid conditions tend to reflect the low amounts and rates of physical, chemical and biological processes typical of such settings (see Chapter 3). High annual temperatures and large diurnal temperature ranges, coupled with an annual net moisture deficiency, results in a hot desert landscape usually with little or no vegetation (Chapters 2 and 4). Soil formation is dominated by in situ physical breakdown of soil and rock, with the resultant soil typically being ‘thin’ and with a low organic content.
When moisture is available it can collapse or swell a soil, often involving salt or carbonate dissolution or crystallization. Soil transport and deposition is dominated by wind-blown (aeolian) processes and, thus, many hot desert soils are composed mainly of fines (sand or finer). Post-depositional modification of soils can involve the displacive introduction and cementation by minerals precipitated by water moving through the ground or through biogeochemical processes leading to the development of hard layers called ‘duricrusts’. While these processes are typically restricted to inland depressions and coastal flats in hot desert environments, there may be more widespread relict examples of their activity in
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Hot Deserts: Engineering, Geology and Geomorphology Engineering Group Working Party Report
This volume provides an authoritative and comprehensive state-of-the-art review of hot desert terrains in all parts of the world, their geomaterials and influence on civil engineering site investigation, design and construction. It primarily covers conditions and materials in modern hot deserts, but there is also coverage of unmodified ancient desert soils that exhibit engineering behaviour similar to modern desert materials. Thorough and up-to-date guidance on modern field evaluation and ground investigation techniques in hot arid areas is provided, including reference to a new approach to the desert model and detailed specialized assessments of the latest methods for materials characterization and testing.
The volume is based on world-wide experience in hot desert terrain and draws upon the knowledge and expertise of the members of a Geological Society Engineering Group Working Party comprising practising geologists, geomorphologists and civil engineers with a wealth of varied, but complementary experience of working in hot deserts.
This is an essential reference book for professionals, as well as a valuable textbook for students. It is written in a style that is accessible to the non-specialist. A comprehensive glossary is also included.