ABSTRACT This field trip explores the geology and mining history of the Bodie Hills with a focus on the Bodie and Aurora mining districts. The field trip starts and ends in Bridgeport, California. Our first geologic stop is at Travertine Hot Springs, which provides an analogy for the style of mineralization observed in the Bodie and Aurora districts. We then proceed south on Highway 395 to the Bodie exit at Highway 270. At this location on Highway 395 is the placer camp of Dogtown with outcrops of till from the Sherwin glaciation. A side trip up Cinnabar Canyon exposes rocks with veinlets of cinnabar and silicic alteration. From here, we travel through several different components of different stratovolcanoes and arrive at the preserved ghost town of Bodie. Bodie Bluff and Standard Hill contain most of the mine workings for the Bodie district. At Bodie we discuss different interpretations of volcanic history and stratigraphy and learn about the U.S. Bureau of Land Management’s 1997 economic appraisal of the mineralization there: 69.8 million tons of ore averaging 0.4 oz/ton Au. Leaving Bodie, we pass through a placer field where William Bodie made his discovery of the mine and the district that bears his name. And then we move through the Bodie volcanics to those volcanic rocks associated with Aurora. On the way to Aurora, we will see the stage stop site of Del Monte. At Aurora, we view the active open pit mining operation and compare this district with Bodie and others in the Bodie Hills. Both Bodie and Aurora were classified as principal gold deposits of the United States.

ABSTRACT This paper summarizes the hydrological variability in eastern California (central Sierra Nevada) for the past 3000 yr based on three distinct paleoclimate proxies, δ 18 O, total inorganic carbon (TIC), and magnetic susceptibility (chi). These proxies, which are recorded in lake sediments of Pyramid Lake and Walker Lake, Nevada, and Mono Lake and Owens Lake, California, indicate lake-level changes that are mostly due to variations in Sierra Nevada snowpack and rainfall. We evaluated lake-level changes in the four Great Basin lake systems with regard to sediment-core locations and lake-basin morphologies, to the extent that these two factors influence the paleoclimate proxy records. We documented the strengths and weaknesses of each proxy and argue that a systematic study of all three proxies together significantly enhances our ability to characterize the regional pattern, chronology, and resolution of hydrological variability. We used paleomagnetic secular variation (PSV) to develop paleomagnetic chronostratigraphies for all four lakes. We previously published PSV records for three of the lakes (Mono, Owens, Pyramid) and developed a new PSV record herein for Walker Lake. We show that our PSV chronostratigraphies are almost identical to previously established radiocarbon-based chronologies, but that there are differences of 20–200 yr in individual age records. In addition, we used eight of the PSV inclination features to provide isochrons that permit exacting correlations between lake records. We also evaluated the temporal resolution of our proxies. Most can document decadal-scale variability over the past 1000 yr, multidecadal-scale variability for the past 2000 yr, and centennial-scale variability between 2000 and 3000 yr ago. Comparisons among our proxies show a strong coherence in the pattern of lake-level variability for all four lakes. Pyramid Lake and Walker Lake have the longest and highest-resolution records. The δ 18 O and TIC records yield the same pattern of lake-level variability; however, TIC may allow a somewhat higher-frequency resolution. It is not clear, however, which proxy best estimates the absolute amplitude of lake-level variability. Chi is the only available proxy that records lake-level variability in all four lakes prior to 2000 yr ago, and it shows consistent evidence of a large multicentennial period of drought. TIC, chi, and δ 18 O are integrative proxies in that they display the cumulative record of hydrologic variability in each lake basin. Tree-ring estimations of hydrological variability, by contrast, are incremental proxies that estimate annual variability. We compared our integrated proxies with tree-ring incremental proxies and found a strong correspondence among the two groups of proxies if the tree-ring proxies are smoothed to decadal or multidecadal averages. Together, these results indicate a common pattern of wet/dry variability in California (Sierra Nevada snowpack/rainfall) extending from a few years (notable only in the tree-ring data) to perhaps 1000 yr. Notable hydrologic variability has occurred at all time scales and should continue into the future.