WHAT DO YOU MEAN MOISTURE IS 110%!
have application in geology and geotechni- cal engineering. Geomorphology: “What is the age of the surface that I am studying?” In this approach the material might be mapped as Sangaman, pre-Sangaman, etc. But engineers often nd the geological xation with age frustrating and are prone to dis- miss reports in which this aspect is high- lighted. The geologist needs to convey the physical consequences of greater age such as more leached soils or devitrication of volcanic ash (e.g. Mitchell, 2009). Climatology: “Under what climate sys- tem did this material form?” In this con- text the soil science terminology of the U.S. Natural Resources Conservation Ser- vice (NRCS) (1999) is likely to be used by geologist, and the material might be ap- propriately designated as a caliche or a vertisol.
Mineral exploration: “What can the soil tell me about the composition of the underlying rocks?” In this application it is common to analyze B-horizon samples taken in a grid for Au, Ag, Pb, Zn, etc. as an indicator of underlying hidden miner- alization. In this context, the distinction of transported vs. in situ material assumes critical importance.
Geotechnical Engineering: “What can I build on this material or what modica- tions are needed to make it suitable for building?” Here the system of classica- tion is quite different and is likely to be confusing to the geologist. Agronomy: “What can I grow in this soil?” In this case “soil” is the unconsoli- dated mineral or organic material on the immediate surface of the earth that serves as a natural medium for the growth of plants. How different soil types are dis- tributed has been a maor focus of the U. S. NRCS, resulting in an exceptionally helpful series of maps and reports grouped by county. Many useful geological and geo- technical properties are tabulated and cer- tain soil types can be correlated to slope instability or to drainage problems. Most professionals consult these tables early in a site investigation. The information pro- vides a useful model of how information can be effectively communicated. Just as with other properties it is criti- cal to explain what convention is being used in reports and on maps. Geologists need to use qualifying descriptions by re- ferring to “in situ” soils and should include specic denitions of size terms. It is not safe to assume that users will understand “silt” and “clay” because many users will not be geologists and will interpret these terms differently from the intention of the report.
Some additional papers that explore the issues of communication are Judd (1967) on construction proects; Kiersch and James (1991) on dams and embank- ments; Katzenbach and Bachmann (2004)
on site investigation; and Hart (2011) on communication among geophysicists, ge- ologists, and engineers. Turner (2008) has provided a wide-ranging review of the in- tersection of geology and civil engineering since antiquity.
Conclusions and Recom- mendations
It is tempting for the geologist to regard failures in construction or excavation as the failure of the civil engineer to consider geologic factors. We opine instead that it is the geologist who has failed to com- municate the existence and importance of these factors. Because the ow of com- munication is almost always downstream from the geologist to the engineer, the bulk of the responsibility falls on geolo- gists to clearly convey the signicance of their results to engineers. Vocabulary, particularly the conflicting terms, needs careful definition to the extent that may seem excessive to most editors.
Certain measurements such as clay content, moisture content and propor- tion of voids should be reported in both systems.
Geological maps and reports should consider a wider audience and, like the Soil Survey Reports, include more infor- mation relevant to engineering such as Atterberg limits and slake durability.
Finally we urge the reader to study the paper by Voight et al. (1981) on the char- acteristics of the debris generated by the 1980 eruption of Mount St. Helens. They present data in both geological and geo- technical formats so that the information is readily understood without confusion by workers in both disciplines.
REFERENCES
American Society for Testing and Materials, 2009, Standard ASTM D6913 - 04(2009) Standard Test Methods for Particle-Size Distribution (Gradation) of Soils Using Sieve Analysis, ASTM International, West Conshohocken, PA, 2009, DOI: 10.1520/D6913-04R09,
www.astm.org. Bishop, A.W., Hutchinson, J. N., Penman, A. D. M., and Evans, H. E. , 1969, Geotechnical investigation into the causes and circumstances of the disas- ter of 21st October, 1966. In: A Selection of Technical Reports Submitted to the Aberfan Tribunal. HM Stationary Office, London, p. 1–82.
Chandler, R.J. and Tosatti, G., 1995, The Stava tailings dam failure, Italy, July 1985, Proceedings of the Institution of Civil Engineers Geotechnical Engineering, V. 113, p. 67–79.
Graves, R., and Hodge, A., 1943, The reader over your shoulder: a handbook for writ- ers of English prose. London , Jonathan Cape, 446p.
Hart, B.S., 2011, An introduction to seismic interpretation, American Association of Petroleum Geologists, Datapages Discovery Series No. 16. CD-ROM. Hatheway, A.W., 2005, Perspectives No. 3: What do we do with the geological engineers? In Perspectives, A Collection of Lessons Learned from a Career of Intense Practice in Engineering Geology, Association of Engineering Geologists Special Publication 13 (CD-ROM), Riverside CA, 7-10.
Hill, C. A., Douglas, R. G., and Hammond, D. E., 2007, A hydrological assessment of groundwater sources in the Portuguese Bend and Abalone Cove landslide areas, California: Implications for landslide movement. In: Brown, A. R., Shlemon, R.J., and Cooper, J. D., (editors), Geology and Paleontology of Palos Verdes Hills, California, Fullerton CA, Pacific Section SEPM-Society for Sedimentary Geology, p. 271-293.
Hunt, R. E., 2005, Geotechnical Engineering Investigation Handbook, 2nd ed., Taylor & Francis, Boca Raton FL, 1066 p. James, L. B., 1988, Lessons from notable events; The failure of Malpasset Dam. In: Jansen, R. B. (editor) Advanced dam engineering for design, construction, and rehabilitation, Van Nostrand Reinhold, New York, NY, p. 17-27.
Judd, W. R., 1967, Geotechnical communica- tion problems, Alex L. du Toit Memorial Lecture No. 10, Geological Society of South Africa, Annexure to volume 70. Katzenbach, R., and Bachmann, G., 2004, Some basic considerations about the necessities and possibilities of coop- eration between civil engineers and engineering geologists. In: Hack, R., Azzam, R., and Charlier, R. (editors) Engineering Geology for Infrastructure Planning in Europe, Springer-Verlag, Berlin, p. 9–14.
Kehew, A. E., 2006, Geology for Engineers & Environmental Scientists, Pearson- Prentice Hall, Upper Saddle River NJ, 696 p.
Kiersch, G. A., and James, L. B., 1991, Errors of geologic udgment and the impact on engineering works. In: Kiersch, G. A. (editor) Heritage of Engineering Geology: The First Hundred Years, The Geological Society of America, Centennial Special Volume 3, Boulder CO, p. 517–558. Krumbein, W. C., and Pettiohn, F. J., 1938, Manual of Sedimentary Petrography, Appelton-Century Crofts, New York, 549 p.
Leggett, R. F., 1939, Geology and Engineering, McGraw Hill, New York, NY, 650 p. Leggett, R. F., 1953, The term ‘soil’, Nature, V. 171, p. 574-575.
Leggett, R. F., 1979, Geology and Geotechnical Engineering, In: Terzaghi Lectures 1974-1982, Geotechnical Special Publication No. 1, American Society of Civil Engineers, p. 127-181.
Liverman, D.G.E., Pereira, C., and Marker, B. (editors), 2008, Communicating
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