Abstract Though systematic studies of the genesis and subsequent evolution of limestone caves and rockshelters are relatively common, notably in Europe (Laville and others, 1980; Farrand, 1981) as well as other parts of the world (Liu, 1988), comprehensive examination of the inception and development of sandstone overhangs and rockshelters are much rarer (Raynal, 1975; Styles and others, 1983). This reflects a somewhat glaring gap in the geological and geoarchaeological literature as sandstone rockshelters are not uncommon in many parts of the New and Old Worlds. Indeed, in some areas (for example, the eastern and southwestern United States), they are quite numerous. Whatever their frequency, sandstone rockshelters, like their limestone counterparts, were often visited and revisited throughout the period of their existence by humans. Indeed, as often highly visible features of the late Pliocene, Pleistocene, and Holocene landscape, sandstone rockshelters in the Old World were utilized as temporary bivouacs, special activity loci, seasonal encampments, or even long-term habitations for tens or occasionally hundreds of thousands of years. In the New World, such sites were utilized where available since the initial peopling of the hemisphere. As they were used by human occupants, sandstone rockshelters, again like their limestone analogues, served as places within which humans operated and interacted, however briefly, with their immediately contiguous environment. Indeed, the size, configuration, exposure, and internal topography of the rockshelter determined the parameters of what its occupants did on or in it. As both archaeologists and their counterparts in geologygeoarchaeology collectively attempt to elucidate or explain the prehistoric

Abstract This field trip consists of a visit to the site of one of the 1906 earthquake relief camps and the City and County of San Francisco Emergency Communications Center facility, located at 1011 Turk Street in San Francisco.