ABSTRACT William Richard Dickinson was born in Nashville, Tennessee, in 1931 and died in Nuku’alofa, Tonga, in 2015. Through a remarkable combination of intellect, self-confidence, engaging humility, and prodigious output of published work, he influenced and challenged (to date) three generations of sedimentary geologists, igneous petrologists, tectonicists, sandstone petrologists, archaeologists, and other geoscientists. Bill grew up in the California Transverse Ranges before heading to Stanford, where he received his B.S., M.S., and Ph.D. While on the Stanford faculty (1958–1979), Bill used a Guggenheim Fellowship in Fiji, New Zealand, and Australia to understand the great mobility of Pacific plates, including relationships between inclined seismic zones beneath island arcs and magmatism, and he began a lifelong study of Pacific potsherds for archaeological studies. In 1969, Bill convened the watershed Geological Society of America (GSA) Penrose Conference at Asilomar, California, on “The Meaning of the New Global Tectonics for Magmatism, Sedimentation, and Metamorphism in Orogenic Belts.” An onslaught of new ideas and insights illuminated plate-tectonic processes, sandstone petrology as a guide to plate-tectonic settings, and plate-tectonic evolution of sedimentary basins. This naturally led to syntheses of Cordilleran basins and tectonics, and Pacific plate tectonics. His most cited papers involve the relation of sand(stone) composition to plate tectonics. Following his relocation to the University of Arizona in 1979, Bill began using detrital zircon as an additional provenance tool, resulting in new paleogeographic reconstructions of North America’s drainage patterns for the late Paleozoic and early Mesozoic. During Bill’s “retirement,” he received the Penrose Medal, the Sloss Award, the Twenhofel Medal, the Rip Rap Award, and the Stanford Distinguished Alumnus Award. He also became a member of the National Academy of Sciences and served as president of GSA. The cumulative impact of Bill Dickinson’s influence on understanding Earth history and processes has been, and will continue to be, among the greatest in the history of our science. The papers in this volume are an impressive tribute to the depth and breadth of Bill Dickinson’s contributions.

Abstract High-elevation tropical glaciers provide records of past climate from which current changes can be assessed. Comparisons among three ice-core records from tropical mountains on opposite sides of the Pacific Ocean reveal how climatic events are linked through large-scale processes such as El Niño–Southern Oscillation. Two distinctive trans-Pacific events in the mid-fourteenth and late-eighteenth centuries are distinguished by elevated aerosol concentrations in cores from the Peruvian Andes and the Tibetan Himalaya. Today aerosol sources for these areas are enhanced by droughts accompanying El Niños. In both locations, large-scale atmospheric circulation supports aerosol transport from likely source regions. Oxygen isotopic ratios from the ice cores are significantly linked with tropical Pacific sea-surface temperatures, especially in the NIÑO3.4 region. The arid periods in the fourteenth and eighteenth centuries reflect droughts that were possibly connected to strong and/or persistent El Niño conditions and Intertropical Convergence Zone migration. These ‘black swans’ are contemporaneous with climate-related population disruptions. Recent warming, particularly at high elevations, is posing a threat to tropical glaciers, many of which have been retreating at unprecedented rates over the last several thousand years. The diminishing ice in these alpine regions endangers water resources for populations in South Asia and South America.