URBAN GEOLOGY 563 habitat and the impact of humans on geologic conditions that serve to support that life Cities are the focus of human activity and this activity takes place on and in the ground, which is itself only a complex of geologic conditions Of all of the qualities of human life in the cities is its dynamism, all of which tends to obscure and often obliterate the delicate evidence of the nature of geologic conditions supporting the city For this reason, we must turn to urban geologic observations and recording in order to compile a sequence of snap-shot views and vignettes of urban geology When recorded, this information is invaluable in the continual struggle to accommodate the great demands See Also Engineering Geology: Aspects of Earthquakes; Natural and Anthropogenic Geohazards; Made Ground; Site Classification; Ground Water Monitoring at Solid Waste Landfills Europe: Holocene Further Reading Figure An example of a zone of ‘bad ground’ discovered and delimited in an engineering geological site characterization ex ploration This zone represents poor engineering properties of foundation materials in terms of their ability to support structural loads that would be imposed by engineered works Shown is a shear zone of ancient tectonic origin, as it perpendicularly enters the foundation excavation for the Lahey Medical Clinic, urban Boston, Massachusetts Such features are important when they are planar to and cross one or more dimension of the foundation excavation, because they have the potential to induce instability of the surrounding ground and existing buildings Timbers are 200 mm2 in section; survey tape in midview Photograph by the author and therefore must be incorporated into the site engineering geological characterization process Geological conditions decidedly influence geotechnical design measures to transfer dead and live loads of proposed structures into the foundation soil or rock (Figure 2) Transfer of load to geological horizons is integral to ensuring adequate structural support for engineered works During the site characterization process, appropriate site exploration techniques must be incorporated to determine the engineering geological conditions likely to adversely impact the project Summary The struggle to provide decent living conditions for humanity on earth is characterized to greatest degree by the interwoven impact of geology on the human Association of Engineering Geologists (1982 2004) Cities of the world Environmental and Engineering Geoscience Journal (annual series) Baskerville CA (1992) Bedrock and Engineering Geologic Maps of Bronx County and Parts of New York and Queens Counties, New York: USGS Miscellaneous Investigation Series MAPI 2003, two sheets, 1:24,000 Washington, DC: US Geological Survey Culshaw MG (2005) Urban geoscience (the Glossop Lecture for 2004) Quarterly Journal of Engineering Geology and Hydrogeology Kaye CA Jr (1959) Geology of the San Juan Metropolitan Area, Puerto Rico: US Geological Survey Professional Paper 417 A Washington, DC: US Geological Survey Kaye CA Jr (1976) The Geology and Early History of the Boston Area of Massachusetts; A Bicentennial Approach: Geological Survey Bulletin 1476 Washington, DC: US Government Printing Office Legget RF (1962) Geology and Cities New York: McGraw Hill Legget RF and Hatheway AW (1988) Geology and Engin eering New York: McGraw Hill McCall GJH, de Mulder EFJ, and Marker BR (1996) Urban Geoscience Rotterdam: Balkema Schlocker J (1974) Geology of the San Francisco North Quadrangle, California: US Geological Survey Profes sional Paper 782 Washington, DC: US Geological Survey Schuberth CJ (1968) The Geology of New York City and Environs New York: Natural History Press United States Geological Survey (1894 1955) Folio series Select titles pertaining to cities; maps at 1:125,000 plus text and photographs Washington, DC: US Geological Survey