Geologic map of Saddle Mountain, Maricopa County, Arizona

Geologic map of Saddle Mountain, Maricopa County, Arizona. Report and one map sheet, map scale 1:24,000.Documents in the AZGS Document Repository collection are made available by the Arizona Geological Survey (AZGS) and the University Libraries at the University of Arizona. For more information about items in this collection, please contact [email protected]

Geologic Map of the Western Eagletail Mountains, La Paz County, Arizona

The area described in this study includes the western Eagletail Mountains, Yuma county, Arizona and includes much of the Eagletail Mountains Wilderness Area (Figure 1). Bedrock in this area consists largely of Miocene silicic volcanic rocks and subordinate mafic and intermediate volcanic units (Plate 1). Sources of data are shown in Figure 2, rock-unit correlations and relative ages are shown in Figure 3, and map symbols are shown in Table 1. The area was mapped in part with funds provided to the Arizona Geological Survey by the U.S. Geological Survey COGEOMAP program, contract #1434-92-A-1061. Field work was carried out by the authors in the winter of 1993. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U. S. Government.Documents in the AZGS Document Repository collection are made available by the Arizona Geological Survey (AZGS) and the University Libraries at the University of Arizona. For more information about items in this collection, please contact [email protected]

Intensifying drought eliminates the expected benefits of elevated carbon dioxide for soybean

Stimulation of C3 crop yield by rising concentrations of atmospheric carbon dioxide ([CO2]) is widely expected to counteract crop losses that are due to greater drought this century. But these expectations come from sparse field trials that have been biased towards mesic growth conditions. This eight-year study used precipitation manipulation and year-to-year variation in weather conditions at a unique open-air field facility to show that the stimulation of soybean yield by elevated [CO2] diminished to zero as drought intensified. Contrary to the prevalent expectation in the literature, rising [CO2] did not counteract the effect of strong drought on photosynthesis and yield because elevated [CO2] interacted with drought to modify stomatal function and canopy energy balance. This new insight from field experimentation under hot and dry conditions, which will become increasingly prevalent in the coming decades, highlights the likelihood of negative impacts from interacting global change factors on a key global commodity crop in its primary region of production. © 2016 Macmillan Publishers Limited, part of Springer Nature. All rights reserved