Lake Tahoe served as both a classroom and a time machine for Western Nevada College geology students recently, as Dr. Winnie Kortemeier, Professor of Geosciences, led three of her classes on a hands-on field trip to uncover the volcanic story that shaped the iconic lake — and proved it to be 2.3 million years old.

Students from Geology of Nevada, Geology 100 and Geology 101 met at Commons Beach in Tahoe City and spent more than four hours exploring three unique sites. Each stop revealed dramatic evidence of volcanic activity that continues to fascinate geologists and inspire students.

At Burton Creek State Park, students hiked among volcanic rocks, spotting roundish chunks of pillow basalt in an orange outcropping that towered 200 to 300 feet above them, all capped by striking columnar basalt. At Skylandia Beach, they examined a massive underwater-formed volcanic tuff cone, more than a mile wide. Dr. Kortemeier explained that the tuff cone formed when lava erupted into water, blasting out material that formed a cone-shaped structure built of visible layers of lapilli and ash.

The tour also included a visit to the historic 18-foot-high Tahoe dam built in 1909 for irrigation in Fallon. For students, it was a chance to connect natural history with human history.

“They are so amazed that they can see the story in the rocks,” Dr. Kortemeier said. “It’s mind-opening when they realize that 2.3 million years ago, where they are standing today was underwater.”

Dr. Kortemeier is uniquely suited to guide such explorations. In 2024, through decades of research and radiometric dating of basalt that interacted with Lake Tahoe’s waters, she confirmed that the lake is at least 2.3 million years old. This discovery established Lake Tahoe as the oldest permanent freshwater lake in North America and one of the oldest in the world.

Students were deeply engaged throughout the trip, with one calling Dr. Kortemeier a “geology angel” for showing them such hidden wonders. “When there are new classes that come together, it opens them to learning about geology,” she added. “These field trips really get students interested in geology and make them want to pursue this field of study in college.”

As the sun sparkled off Tahoe’s blue waters, students not only learned about the ancient volcanic forces that shaped the region but also felt inspired by the chance to stand on history itself — a classroom 2.3 million years in the making.

To learn more about WNC's Geology program, email Dr, Kortemeier at winnie.kortemeier@wnc.edu.