For more than 3,000 years, sediment settling at the bottom of Colorado’s Columbine Lake recorded the region’s changing dust burden. A new study led by Franklyn Telles, a 2026 PhD graduate in Earth Sciences and Environmental Sustainability at Northern Arizona University, finds that the most important sustained shift began around 1667, during Spanish colonial settlement, rather than during the 19th-century American expansion often identified as the main turning point.
“Columbine Lake acts as a natural ‘dust catcher,’ continuously capturing sediment for at least 3,400 years,” Telles wrote. The oldest layers lie at the bottom, while newer layers accumulate above them, preserving a record that can be compared with evidence of drought, land use and settlement across the Four Corners region.
Telles and co-authors combined two kinds of evidence from the lake sediments. Grain size and geochemical measurements estimated how much of the sediment arrived as windblown dust. A detailed chronology based on annual laminations, or varves, was integrated with radiometric dates. The team propagated uncertainty through 900 possible age-and-dust reconstructions, then used change-point analysis to identify shifts that were sustained rather than brief fluctuations.
That approach placed the onset of a major regime change at 1667 CE, with a 95% confidence interval from 1640 to 1740. Dust accumulation later reached a peak median value of about 30 grams per square meter per year in 1761, the highest level in the 3,400-year record. The improved chronology moved the estimated onset 150 to 200 years earlier than some previous studies based on less precise dating methods.
The timing matters because dust and drought did not show a consistent relationship before the late 17th century. That relationship became increasingly strong afterward. In the 20th century, dry periods such as the Dust Bowl coincided with high dust accumulation, but the initial 1667 shift began when climate alone could not account for the change. The paper attributes the transition primarily to land-use changes associated with Spanish colonization, including livestock and agricultural systems that disrupted existing landscape protections.
The study also cautions against treating all intensive land use as inherently destabilizing. Telles points to Indigenous practices such as gravel mulching, check dams, terraces and other forms of water- and soil-conserving landscape management. The lake record shows little major dust response during periods when Ancestral Puebloan communities maintained extensive agriculture and settlements, despite substantial climate variability.
“Indigenous stewardship actively engineered long-term landscape resilience through moisture-conserving, soil-stabilizing practices,” Telles wrote. In contrast, the paper describes how colonial extraction and grazing reduced vegetation cover and weakened systems that had helped protect dryland soils.
The history also has consequences for the future. Telles argues that Earth-system models may underestimate Southwestern dust emissions because they do not fully represent biological soil crusts, brown vegetation, coarse mineral dust or localized source areas. He connects that concern to his interdisciplinary training and current work as an air quality specialist with the Institute for Tribal Environmental Professionals. His NAU research brought together the rock record, atmospheric dynamics and geomorphology, while collaborations with the Department of Anthropology and ITEP connected the project to regional communities and environmental education.
For Telles, the long record offers a practical lesson: modern dust and land-management planning should look beyond 19th-century baselines and consider how soil-stabilizing practices informed by Indigenous stewardship might help reduce vulnerability.
Reported by Guy Clawdsen for the School of Earth and Sustainability.