THE IMPACT OF CHARLES L. PILLMORE ON THE COAL GEOLOGY OF THE RATON BASIN—AN OVERVIEW

Perhaps the greatest impact of the late Charles L. “Chuck” Pillmore of the U.S. Geological Survey on the geology of the Raton Basin of Colorado and New Mexico was his work on the Cretaceous-Tertiary (K-T) boundary, but long before that he pioneered research on the coal stratigraphy and correlations, mapping, and economic geology of the basin. His scientific work will endure because of his foresight in sharing his knowledge with colleagues, and we are just two of the many who benefit from his legacy. Chuck Pillmore’s voluminous work on the coal geology of the Raton Basin included stratigraphic investigations and mapping that began in the early 1970s. He concentrated on the geology of the coal beds in the Cretaceous Vermejo and Cretaceous-Tertiary Raton Formations, with emphasis on coal-mining history and recent mining development. Adept at understanding the complexities of coal stratigraphy, he involved other geologists in studies on sedimentology, palynology, geochemistry, paleomagnetism, and radiometric dating to determine the depositional environments of coal and related deposits. Flores worked with him in the 1980s, and Nichols in the 1990s. In the early 1980s, Chuck worked with the team that discovered the first K-T boundary known in nonmarine rocks in a core from coal-bearing strata of the Raton Formation. A thin claystone layer—ejecta from the K-T impact—is present at the boundary. Impact debris rained down on broad floodplains with active and abandoned stream channels, levees, crevasse splays, lakes, ponds, and coal-forming mires. Chuck’s keen observational skills and knowledge of basin stratigraphy quickly led to the discovery of the K-T boundary in outcrop; it is now recognized at numerous localities throughout the basin, because of his efforts. This extraordinary marker bed permits observations of depositional environments throughout the basin at that instant in time. Chuck Pillmore’s impact in the Raton Basin went beyond coal geology and research on the K-T boundary to include the discovery of dinosaur tracks associated with the boundary as he continued his investigations of the stratigraphy of the Raton Formation, even after retirement. In his final years working as a USGS emeritus scientist, he completed the maps of the basin that will serve as guides to future coal mining and coalbed methane development.