Erosion, sedimentation, and fluvial systems
The development of knowledge in erosion and sedimentation parallels the growth of the geological sciences. In his Illustration of the Huttonian Theory of the Earth, Playfair (1802) provides lucid descriptions of erosional processes, illustrating their significance in the evolution of landscapes. Sir Charles Lyell (1830) described in uniformitarian terms the nature and importance of erosion and sediment transport. The power of rain to erode surface materials was discussed by Greenwood in 1857. Reports of the exploration of the American Southwest by the U.S. Geological Survey in the latter half of the nineteenth century are replete with the consideration of the impact of erosion and sedimentation in shaping the landscape. Most notable among these reports are those of G. K. Gilbert, whose keen observations and analytical powers allowed him to develop the basis for many of today’s important concepts in fluvial geomorphology (Gilbert, 1880).
As the geological sciences moved into the twentieth century, Gilbert continued to provide theoretical bases for the comprehension of erosional and sedimentary processes. His classic discussion “The transport of debris by running water” was the result of years of flume studies and field observations (Gilbert, 1914). Gilbert’s contributions in this paper include not only a detailed discussion of processes but one of the first analytical statements regarding the impact of man on a fluvial system. Twenhofel’s (1932) famous Treatise on Sedimentation advanced our fledgling knowledge of sedimentary processes. From the field of soil conservation, Bennett (1939) synthesized existing knowledge of the impact of agricultural practices on erosional processes and sedimentation.
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A review of milestones and changes in geological theory and practice from which modern engineering geology in North America has developed. Five chapters discuss historical events and the contributions of early scientists and engineers; nine chapters review the state of knowledge of dominant geologic processes, phenomena, and specialized principles critical to modern practice; and three chapters discuss geologic environs and the properties of construction materials. Four chapters are devoted to geoscience investigations and related techniques for: initial regional-areal evaluation of conceptual candidate sites (Phase I); selection of preferred-designated sites and design (Phase II); typical kinds of investigations used during project construction (Phase III); and as-built documentation and explorations of the operating or rehabilitation phases. Closing chapters focus on the geoscientist's responsibilities relative to engineering failures, errors of judgment that impact works, litigation, and forensic geoscience. The 34 contributors present extensive case histories applicable worldwide.