Publications

Expanded excavations at White Sands National Park have unearthed 20 stratigraphic horizons containing in situ human footprints, megafaunal trackways, and linear features created by travois. Advances in radiocarbon dating of conifer pollen, combined with ages of aquatic seeds, refines the chronology of the footprint-bearing sequence to between 23.5 and 21.7 thousand years ago (ka)...

No abstract available.

Roos (2026) proposes an intriguing cultural mechanism to account for the rare (

Wind protection is a central focus of western monarch butterfly (Danaus plexippus) overwintering habitat conservation. The Wind Disruption Hypothesis guiding management decisions predicts that winds at or above 2 m/s disrupt clusters and that cluster abundance decreases as wind speed increases. At two California groves during the 2023–2024 overwintering season, we paired time-lapse...

Geochronological and thermochronological data are essential for constraining the timing and rates of geological processes, supporting geologic mapping, natural hazard assessment, and resource exploration. The U.S. Geological Survey (USGS) Geochron Database is a centralized, relational database that integrates USGS and State geological survey data in accordance with the National Geologic...

The U.S. Geological Survey collects remote sensing data to support national scientific assessments of natural resources, hazards, and landscape change. Spectrometers and spectroradiometers are essential for gathering point-based spectral measurements used in applications such as uncrewed aerial systems (UAS) multispectral image calibration, validation, and analysis. Evaluating how...

The extent of grasslands has contracted globally, leading to significant declines in grassland-obligate species, including birds. Grassland birds are threatened by multiple factors, including grassland conversion to cropland, and development, including energy infrastructure. In the USA, the federal Conservation Reserve Program (CRP) provides financial incentives for agricultural...

The timing and nature of early deformation in the Rio Grande Rift remains poorly constrained. We present evidence for the earliest structural signature of rift extension in the Sangre de Cristo Range, southern Colorado, based on new geologic mapping, structural analysis, rock magnetic data, and thermochronology. These analyses focus on the ~30.0 Ma granite of Chokecherry Canyon, which...

The Conservation Reserve Program (CRP) is one of the most extensive private-land conservation programs in the United States, aimed at mitigating habitat loss and supporting biodiversity in agricultural landscapes. Individual studies of CRP effects on wildlife report mixed results, necessitating a comprehensive synthesis. We conducted a meta-analysis and vote-counting assessment of 96...

The mantle sources of carbonatite and alkaline magmatic systems that host rare earth element (REE) deposits are difficult to constrain because whole-rock compositions are commonly altered. Alteration-resistant zircon trace-element compositions are used to fingerprint mantle sources at Mountain Pass, California, the largest REE deposit in the United States, and extend this approach to a...

Uncertainty remains regarding the impact of rapid anthropogenic warming on forest ecosystem structure, biodiversity, and function. As an analog, we reconstruct forest canopy density and compositional change in Wyoming, USA, through the Paleocene-Eocene Thermal Maximum (PETM), an interval of abrupt carbon increase and warming ~56 million years ago. We develop a proxy to quantify leaf area...

The Mammoth Site (MS) at Hot Springs, South Dakota, provides a unique opportunity to reconstruct paleoenvironmental conditions on the Northern Great Plains of the United States. Previous radiocarbon analyses of mammoth bone apatite suggested the MS sinkhole was deposited ∼42–23 cal ka BP. However, two U-series ages and one thermoluminescence (TL) age ranged between 150 and 101 ka...