WNC professor: Lake Tahoe is North America’s oldest freshwater, permanent lake, 3rd oldest in world

Before considerable scientific research by Western Nevada College Professor of Geosciences Dr. Winnie Kortemeier, it was understood that Lake Tahoe, the largest alpine lake in North America, was created during the Pleistocene era, also known as the Ice Age, roughly 10,000 to 2.6 million years ago.

Through her radiometric dating of rocks and examining the basalt that has interacted with the water of Lake Tahoe, Dr. Kortemeier has determined that the lake is 2.3 million years old.

As a result, Dr. Kortemeier has concluded that Lake Tahoe is North America’s oldest freshwater, permanent lake — and the third oldest in the world.

“Fortunately, basaltic lava flows interacted with the lake water and lake sediments when the lava erupted millions of years ago. We were then able to radiometrically date the basalt to determine the age of Lake Tahoe,” Dr. Kortemeier said. “After looking at the data from other ancient lakes, I was surprised to find that it’s the third-oldest lake in the world.”

Dr. Kortemeier will present her findings at the Geological Society of America’s annual meeting on Sept. 23 at the Anaheim Convention Center in Anaheim, Calif.

“I'm sure Dr. Kortemeier's discovery about Lake Tahoe makes us all feel a little bit younger. Seriously, we are extremely proud of Dr. Kortemeier and her research,” said WNC President Dr. J. Kyle Dalpe. “She's a great role model for our students and brings a variety of real-world experiences to them in the classroom.”

A summary of her findings can be viewed at https://gsa.confex.com/gsa/2024AM/meetingapp.cgi/Paper/405032.

Dr. Kortemeier has been conducting research at Lake Tahoe since 2005 and received her doctorate degree in Geology from the University of Nevada, Reno in 2012. In her doctorate program at UNR, she focused on the Pleistocene volcanism and shifting shorelines at Lake Tahoe.

“I love Lake Tahoe and its spectacular geology. I take students up there every semester on field trips, and I do like sharing what I know about it,” she said.

The Tahoe Basin and Lake Tahoe formed from active faults that created the Carson Range and Sierra Nevada. The oldest lakes in the world — Lake Baikal, Siberia (5-10.3 million years old) and Lake Tanganyika, East Africa (8-10 million years old) — were also created by extensional fault-block basins, establishing them as permanent lakes.

“These really old lakes have active faults, so they don’t fill up with sediment,” Dr. Kortemeier said.

After a one-year sabbatical that allowed her to wrap up the research project on Lake Tahoe, Dr. Kortemeier learned how much she missed teaching.

“I’d like to teach forever. I missed all of the interaction that I have with staff and students,” said Dr. Kortemeier, who began her 35th year teaching at WNC in August. “Typically, sabbaticals show people how appealing retirement might be, but it showed me the opposite.”

There still is time to register for Kortemeier's Geology 105 National Parks class, which starts Oct. 7. Learn more about the geology of U.S. national parks, including Great Basin National Park in Nevada. The class meets on Wednesdays from 1 to 3:45 p.m. Online and in-person options are available. For more information, phone 775-445-3267.