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Book Chapter

Geopractitioner approaches to working with antisocial mélanges

Edmund W. Medley
Edmund W. Medley
Geological Engineer, Belmont, California, USA
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Dimitrios Zekkos
Dimitrios Zekkos
Department of Civil and Environmental Engineering, 2358 GG Brown Laboratory, 2350 Hayward Street, University of Michigan, Ann Arbor, Michigan 48109-2125, USA
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August 2011

Although mélanges are exciting, puzzling, and controversial to geologists, it is geopractitioners and contractors who must work with them to engineer the constructed works of Society. Geopractitioners include geotechnical engineers, geological engineers, engineering geologists, and rock engineers. Mélanges are the most intractable bimrocks (block-in-matrix rocks), complex geological mixtures composed of hard blocks of rocks surrounded by weaker matrix, and are famously exemplified by those within the Franciscan Complex of Northern California. Bimrocks also include olistostromes, weathered rocks, fault rocks, and lahars. The conventional characterization, design, and construction procedures used by geopractitioners for well-behaved stratified rocks and soils are not well suited to mélanges. The considerable engineering and construction difficulties related to mélanges burden Society to the extent that they can be considered “antisocial.” Case histories exemplify a recommended systematic procedure for characterization, design, and construction with mélanges. Geopractitioner approaches to characterizing California's chaotic Franciscan mélanges are applicable to geologists and geopractitioners working in fault zones, weathered rocks, lahars, and other bimrocks, and suggestions are offered for collaborative research between geologists and geopractitioners.

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GSA Special Papers

Mélanges: Processes of Formation and Societal Significance

Edited by
John Wakabayashi
John Wakabayashi
Department of Earth and Environmental Sciences, California State University, Fresno, Fresno, California, USA
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Yildirim Dilek
Yildirim Dilek
Department of Geology, Miami University, Oxford, Ohio, USA
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Geological Society of America
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