In the Field at Mineral King

(From left) Dr. Greene, Cory, and Conner after summiting the 11,947 ft. Vandever Mountain at Mineral King, with Mt. Whitney in the distance.

After nineteen days in sunny California, Dr. Greene, Cory, and I have returned to Ohio. Our field session was a great success, giving us scores of samples to begin analyzing in the coming weeks. Dr. Greene was an excellent field leader for us new geologists, and a big thanks goes out to him and his parents for hosting us during our days in San Francisco. The trip was a tremendous learning experience, and what better location than the beautiful Sierra?

The Mineral King Valley is located within Sequoia National Park, a few hours east of Visalia, California. We drove the six or so hours from Daly City (near San Fran), at sea level, to the campground at over 7,000 ft. in elevation. From there, our hiking and field work ranged from 8,000 ft. to nearly 12,000. Never before had I done such strenuous hiking at such a high elevation. There’s no room to write all of the awesome things (geological or otherwise) that we saw, but the highlights ranged from seeing abundant wildlife, a bear, and the stunning views of mountain lakes and panoramas of the Southern Sierra from the tops of high peaks.

Conner and Cory in Mineral King Valley, Timber Gap and the colorful pendant rocks in the background.

Then, of course, there’s the geology. Cory and I had some time to develop our “elevator speech” through talking to the various hikers curious about our astoundingly heavy packs and our rock hammers. Most hikers were genuinely interested in the rocks of the beautiful valley. Our speech went a little something like this:

The Sierra Nevada most people think of is made up of gray-white granite, the same granite that rock climbers love. Granite comes from deep within the crust essentially as a liquid magma. It bubbles up in large plutons that wipe away most of the previously existing crust. The red and brown rocks seen throughout Mineral King (see above) are remnants of the sedimentary and volcanic rocks that the granitic magma intruded into. When the granite was emplaced, these older rocks were stretched, squeezed, heated, and sheared into the metamorphic rocks present today, and all this happened many kilometers beneath the earth’s surface. Over millions of years, the rock on top was weathered away, exposing the mountains that tower over the landscape now. Our research is focused primarily on the metamorphic remnants left between the classic granite mountains.

I am working with Dr. Erik Klemetti to analyze the ages of these older rocks (roughly 100-130 million years old) in order to understand that magmatic systems that both formed the Sierra and existed previously. Cory and Dr. Greene are studying the structure of the metamorphic rocks to analyze the strain and stress that deformed them during the intrusive process. All of this will give us a better picture of what happened at Mineral King and how mountains like the Sierra Nevada form. We hope to take geologic knowledge of the Mineral King Pendant to the next level, based on the important research of other geologists who have been working on this area for the past few decades.

Sheared granitoid in mylonitic zone. This is one of the samples now ready to date this week.

The field session was a lot of fun, and more importantly, my geological knowledge in this area increased immensely. I’m looking forward to what data arises and how that compares to the data that we have now. I can’t wait to see what the rocks tell us.

For more pictures from the trip, check out my web album!

Conner Toth

Conner Toth '15 Geoscience Major Spanish Minor