The Long Valley caldera area was also scientifically important before the onset of the current unrest. Lying at the eastern foot of the Sierra Nevada, the deposits from this active volcanic system have provided fertile ground for research into Neogene tectonics, Quaternary geology and geomorphology, regional stratigraphy, and volcanology. In the early 1970's intensive studies of the area began through the USGS Geothermal Investigations Program owing to the presence of a large young silicic volcanic system (Muffler and Williams, 1976). The paroxysmal eruption of Long Valley caldera, ca. 760 ka, produced the Bishop Tuff and associated Bishop ash (Gilbert, 1938; Bailey and others, 1976; Hildreth, 1979). The Bishop Tuff is a well preserved ignimbrite deposit that has continued to provide new and developing insights into the dynamics of ignimbrite forming eruptions (e.g. Wilson and Hildreth, 1997). Another extremely important aspect of the Bishop Tuff is that it is the oldest known normally magnetized unit of the Brunhes Chron. Thus, the age of the Bishop Tuff is used to define the beginning of the Brunhes Chron and helps constrain the Brunhes-Matuyama boundary (Izett and Obradovich, 1994). The Bishop ash was dispersed as far east as Nebraska, Kansas, and Texas, and provides an important tephrostratigraphic marker throughout the western United States (Ward et al., 1993; Izett, 1982).

The obsidian domes of both the Mono and Inyo Craters, which were produced by rhyolitic eruptions in the last 40,000 years have been well studied, including extensive scientific drilling through the domes (Eichelberger, 1989). Exploratory drilling has also occurred on the resurgent dome of the caldera (Hill and others, 1998) and within the Casa Diablo geothermal field (Smith and others, 1977). Aside from scientific drilling, the Casa Diablo geothermal field has been developed and is currently producing electricity (Duffield and others, 1994).

Studies in all of the above mentioned fields have contributed to the extensive scientific literature published on the Long Valley caldera region. Although the majority of scientific literature on Long Valley has been produced since 1970, a significant amount of historical literature extends back to the late 1800's. The purpose of this bibliography is to compile references pertaining to the Long Valley region from all time periods and all earth science fields into one single listing, thus providing an easily accessible guide to published literature for current and future researchers.

Figure 1. Graph showing the distribution of references by type.

Book and book sections comprise 12% of the bibliography with 188 references. This category includes portions of Geological Society of America Special Papers as well as chapters published in books about hazard management and techniques for volcano monitoring (e.g., Sheridan, 1968; Andrews, 1968). Proceedings from meetings are also included in this category (e.g., Liddicoat and Bailey, 1989), and generally are distinguished from abstracts by being over one page in length.

Government reports are fourth in number with 120 references or 7% of the total. This category includes all State and Federal documents such as U.S. Geological Survey Professional Papers and Open-File Reports. Exceptions to this apply when a governmental agency has published meeting abstracts, such as the International Association of Volcanology and Chemistry of the Earth's Interior (1989), Continental Magmatism Abstracts, published as New Mexico Bureau of Mines and Mineral Resources Bulletin 131. In this case the references are included in the abstract category. One other exception is the field guide to the Long Valley area by Bailey and others (1989) published in New Mexico Bureau of Mines and Mineral Resources Memoir 47 that is included in the book and book section category.

The final and smallest category is theses, making up 4% of the bibliography. A total of 66 theses including 29 Master's and 37 Ph.D. theses have been written on Long Valley. Subject matter for the theses varies from geological mapping (e.g., Dunn, 1951), to volcanic geology and petrology (e.g., Bailey, 1978), to the seismic structure of the area (e.g., Mayeda, 1991).

The number of references for each discipline keyword varies from seismology with 451 references to atmosphere with eight references. The other disciplines are linearly distributed between these two end members.

Figure 1. Graph of the distribution of references published per decade from 1880 through 1999 showing the increase in published literature since the 1960's.

The number of published references jumped significantly in the 1980's. This abrupt increase is related to the onset of unrest within the caldera and implementation of the USGS effort to monitor the unrest both as a basis for understanding the nature of the unrest and its implications for providing advance warning of an impending eruption. The papers cover a wide range of topics such as ground deformation (e.g., Castle and others, 1984), seismicity (e.g., Ryall and Ryall, 1983), and the consequences of a large scale eruption (e.g., Miller and others, 1982). They include two special issues in the Journal of Geophysical Research devoted to Long Valley caldera (Hill and others, 1985; Goldstein and Stein, 1988). Also during the early 1980's, the Casa Diablo geothermal field was developed and in 1985 was put into production (Duffield and others, 1994).

The publication rate during the 1990's dropped off slightly from the 1980's level, although the rate remained high compared to pre-1980 levels. The elevated number of publications reflects the continuing unrest within the caldera, the continuous stream of real-time geophysical data, and the emergence of a new volcanic phenomenon during the 1990's. Recognition of "tree-kill" areas caused by magmatic CO2 effusing from the ground in the vicinity of Mammoth Mountain, for example, spurred a sequence of publications (e.g., Farrar and others, 1995). Also, new forms of monitoring, such as the use of the Global Positioning System, began to be utilized within the caldera during this decade adding to the literature (e.g., Marshall and others, 1997).

Persons wishing to develop an understanding of the geological history and ongoing unrest of the Long Valley caldera and associated volcanic fields, and who are new to the subject, may find the sheer volume of literature on the area to be daunting. An overview of the subject matter can be gained by reading the following papers: Bailey and others, 1976; Bailey, 1989; Bailey and Hill, 1990; Hill and others, 1985; Rundle and Hill, 1988; Ryall and Ryall, 1981; Hermance, 1983; Langbein and ohters, 1993; and Sorey and others, 1991.

PDF version of entire Open-File Report 00-221
The document is 156 pages long and the file size is approximately 1 MB. It can be viewed using version 3.0 of Acrobat Reader.

For questions about the content of this Open-File Report, contact J.W. Ewert

Department of the Interior
U. S. Geological Survey

U.S. Department of the Interior
Bruce Babbit, Secretary

U.S. Geological Survey
Charles Groat, Director

¹USGS Cascades Volcano Observatory
5400 MacArthur Blvd.
Vancouver WA 98661