Western Nevada College Professor of Geosciences Dr. Winnie Kortemeier has determined that Lake Tahoe is 2.3 million years old, making it North America’s oldest freshwater permanent lake and the third oldest in the world. This conclusion was reached through radiometric dating of rocks and examination of basalt that interacted with the lake's water.
“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 explained. “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 September 23 at the Anaheim Convention Center in Anaheim, California.
“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 online.
Dr. Kortemeier has been researching Lake Tahoe since 2005 and earned her doctorate degree in Geology from the University of Nevada, Reno in 2012, focusing on 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 stated.
The formation of Lake Tahoe is attributed to active faults creating extensional fault-block basins similar to those forming other ancient lakes such as Lake Baikal in Siberia (5-10.3 million years old) and Lake Tanganyika in East Africa (8-10 million years old).
“These really old lakes have active faults, so they don’t fill up with sediment,” noted Dr. Kortemeier.
After a one-year sabbatical dedicated to completing this research project, Dr. Kortemeier expressed 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.
There is still time to register for Dr. Kortemeier's Geology 105 National Parks class starting October 7, which includes both online and in-person options.