A place to explore the natural setting (geology, flora & fauna), people, constructed infrastructure and historical events that play and have played a part in shaping the Sierra Nevada as we know it today.
Our own giantbrookie is the resident expert in this piece.
Ask Me: Ancient lava flow created Fresno County’s Table Mountain
BY PAULA LLOYD
Special to The Fresno BEE
March 7, 2015
Question: When I flew over Table Mountain over 20 years ago it looked like an ancient lava flow. A few years later when I climbed Pin Cushion Mountain with my two daughters we found volcanic material at the top. What is the history of Table Mountain? Was there an ancient volcano nearby?
— Woodrow Nichols, Fresno
Answer: Table Mountain is indeed an ancient lava flow “about 10 million years old,” according to John Wakabayashi, associate professor of geology at California State University, Fresno.
The creation of Table Mountain began when lava from a volcano far to the east filled the ancestral San Joaquin River canyon, he said. After the Sierra Nevada range was pushed up, soil erosion left the ancient, flat lava bed higher than the surrounding area.
“It’s inverted topography,” Wakabayashi said.
An article in the December 2012 newsletter of the Sierra Foothill Conservancy said the lava flow came from a volcano in Nevada.
“That’s likely, but it’s not confirmed. It was at least east of the Sierra Nevada,” maybe around Mono Lake or north and east of there, Wakabayashi said.
Eric, thanks for posting. Interesting. What I remember reading about the tabletops as a girl growing up in Fresno is that they were once the valley floor, which was then uplifted. Erosion than wore away the softer material around the tabletops. I didn't know about this column in the Bee.
