PVCC Faculty John Douglass’ Decades-Long Research Helps Unlock Grand Canyon Origins
For more than 20 years, Paradise Valley Community College Geography Professor John Douglass has been driven by a single, complex question: how did the Grand Canyon form?
Now, as a co-author on newly published research, Douglass is helping provide some of the strongest evidence yet to answer that question, supporting the very theory he has spent decades developing. The study, which examines the origins of the Colorado River, offers new data backing the long-debated “lake spillover” hypothesis, suggesting the river once flowed into an ancient lake that eventually overflowed and carved its way through the landscape to form the Grand Canyon.
Published in April 2026 in Science Magazine, the paper titled “Late Miocene Colorado River arrival in the Bidahochi basin supports spillover origin of Grand Canyon” provides compelling new evidence that strengthens this theory.
Researchers analyzed uranium-lead dating from thousands of zircon crystals found in rock formations both upstream and downstream of the canyon. These crystals revealed a distinct sediment “fingerprint,” showing that Colorado River material reached an upstream lake in the Bidahochi Basin around 6.6 million years ago. From there, the system eventually connected through what is now the Grand Canyon and beyond.
While multiple geologic processes likely contributed, the findings strongly support the idea that an ancient lake overflowed, cutting a path that would become one of the most iconic landscapes on Earth.
“You never want to say you believe something 100 percent,” Douglass said, “but I just felt it was true. So, I wasn’t surprised when the data came back showing that (the sediment) was there.”
From Student Curiosity to Scientific Contribution
Douglass’ fascination with the Grand Canyon began in 1997 as an undergraduate student at Northern Arizona University (NAU). What started as curiosity quickly became a lifelong pursuit.
He continued exploring the question during his master’s work, focusing on the idea that a large lake system once played a role in shaping the canyon. Later, while earning his doctorate at Arizona State University (ASU), Douglass built an innovative “sand table” model to test multiple formation scenarios.
“The reason the Grand Canyon is so fascinating is that the Colorado River crosses a mountain to cut the canyon; but water can’t flow uphill,” Douglass explained. “So, something had to be different in the past.”
His dissertation, published in the Geological Society of America, laid important groundwork for future research. After a pause as career and family took priority, Douglass re-engaged with the topic in 2017, contributing to research on rivers that cross mountain ranges. That work led to a 2020 publication further exploring the spillover theory alongside a team of collaborators.
The latest 2026 paper represents a significant milestone – not only scientifically, but personally. Douglass is the third author among a team of 10 researchers in what he describes as a meaningful and collaborative effort.
“It feels great to be a part of a community and not just out there on my own,” he said.
Working with colleagues, including longtime collaborator Brian Gootee, the team built on earlier observations that sediment in the Bidahochi Basin closely matched material found downstream of the Grand Canyon. Additional research confirmed these similarities, and the zircon crystal analysis ultimately provided the clearest evidence yet tying the system together.
Bringing Discovery Into the Classroom
At PVCC, Douglass shares this passion with his students, turning complex geologic questions into hands-on learning experiences. Each year, he leads Honors students on immersive trips along the South Rim of the Grand Canyon. Through guided hikes, mini-lectures, and field sampling, students explore the canyon’s geological and paleoclimatic history firsthand, engaging directly with the same questions that have shaped Douglass’ career.
His work has also gained national attention, with his research featured on National Geographic and the History Channel.
For Douglass, this recent publication is more than a professional achievement; it’s the culmination of decades of curiosity, persistence, and belief in a scientific idea that has now gained strong supporting evidence. His contributions not only deepen our understanding of the Grand Canyon’s origins, but also highlight the value of long-term research and collaboration in advancing knowledge.
For more information on PVCC, the Honors program and Geology program, visit the website.