This chapter discusses the Quaternary stratigraphy and history of selected areas of the western margin of the conterminous United States. Not included in this discussion are the effects of glaciation and volcanism, which have been well described elsewhere (e.g., Porter, 1983; Easterbrook, 1986; Luedke and Smith, this volume). The geomorphology of the region, though intimately tied to its Quaternary history, is discussed by Muhs and others (1987).
Knowledge of the Quaternary geology and history of the West Coast region of the United States has increased significantly in the 25 years since the last major review papers by Wahrhaftig and Birman (1965) and Crandall (1965). Passage of the 1969 National Environmental Policy Act (N.E.P.A.) combined with increasing concern for environmental impacts and geologic hazards to emphasize the need to more fully understand Quaternary stratigraphy: for example, to establish the recurrence interval of faulting (e.g., Rockwell and others, 1984; Sieh and others, 1989), of flooding (e.g., Costa, 1978), or of landslides (e.g., Crandall, 1971); to better define liquefaction susceptibility (e.g., Dupre and Tinsley, 1980; Tinsley and others, 1985), or to evaluate potential volcanic hazards (e.g., Crandall and Mullineaux, 1978). To improve stratigraphic resolution, Quaternary geologists have increasingly relied on new techniques such as pedostratigraphy (e.g., Morrison, 1978; McFadden, 1988), isotopic and aminoacid dating (e.g., Kennedy and Lajoie, 1982), tephrochronology (e.g., Sarna-Wojcicki and others, and Davis and).