In his words: Cal State Fullerton undergrad searches for clues to volcanic eruptions in new window

John Ayers with Dr. Vali Memeti

October 11, 2017

We left well before dawn in my Toyota Yaris and made the 382-mile journey this summer from Whittier to Tuolumne Meadows in Yosemite National Park. My 19-year-old brother, Matthew, rode shotgun and relaxed in the car en route. My younger brother accompanied me on this journey to be my field assistant and hiking companion — a safety precaution — and to help me carry out rock samples for later study in the lab.

The entire car ride was a mixed bag of emotions for me: immensely excited to backpack, camp and get the chance of a lifetime to do some awesome field work, yet feeling a little nervous and scared at the same time. One thing Vali Memeti, assistant professor of geological sciences and my research adviser, has often mentioned is that if you’re scared or worried, it’s because you care about what lies ahead, and you want to succeed or do well.

My objectives for the field trip were to map the selected research area and collect samples for geochemical analyses to be performed in the lab as research for my undergraduate thesis, “Investigating Causes of Compositional Variation in the Half Dome Grandiorite, Tuolumne Intrusive Complex, Yosemite National Park, California: Big or Small Magma Chambers?”

In the field, the research consisted of mapping the eastern lobe of the Half Dome granodiorite unit found in Lyell Canyon in Tuolumne Meadows. Gaining an understanding of the growth and evolution of magma — molten rock found in deep reservoirs preserved in fossilized magma chambers known as plutons — provides knowledge of the magma plumbing of volcanic eruptions at the surface.

A better insight into how volcanic eruptions are connected to magma reservoirs and what processes cause these eruptions might improve the ability to predict future volcanic events. By researching the compositional variations in plutons, geologists can determine a sequence of events about how magma systems behave, like a detective trying to solve a mystery.

In Tuolumne Meadows, we observed compositional variations by recording and taking measurements of magmatic foliation, mineral abundance and characteristics associated with the half dome granodiorite unit.

We spent six days in the field backpacking in, close to seven miles along the John Muir Trail. Being first-time backpackers made us nervous, so we were fortunate to have had help from two graduate students, Louis Oppenheim and Melissa Chambers.

They had conducted field work in similar areas and spent the first few days camping with us. After being with the grad students and spending a full day of mapping and sample collecting with Memeti, I spent the remainder of the week walking across the canyon mountainside mapping the half dome granodiorite unit. Setting up a routine and working all day long in the Yosemite Valley landscape was both strenuous and mixed with tremendous natural beauty. We spent our lunch breaks eating in the middle of the woods overlooking the Tuolumne River.

At night, we would filter water and start a camp fire. After eating dinner, I’d update my field map and reflect on the day.

Each morning, we arose tired and exhausted after a full day of hiking, however, the cool Sierra Nevada breeze kept us going strong, focusing on the daily objectives.

My morning routine included making sure to have all the necessary gear with us for the long day ahead. The pack list included a G.P.S. unit, map board, azimuthal compass, sunscreen, insect repellent, food and, most important, water.

Many afternoons were spent sweating in 80-degree heat, after having kept a wary eye on possible storm clouds forming throughout the morning. The storm clouds passed over us multiple times only to rain and thunder over the next ridge. Our last afternoon in the field brought excitement as we dashed for cover during a hail and rain storm in Lyell Canyon. We found safety under sparse trees on lower ground.

Another memorable part of the experience in the field was meeting hikers along the John Muir and Pacific Crest trails. Our campsite was set up along the John Muir Trail, and on a few nights, we were joined by a couple of solo hikers, pausing along their treks to spend the night. Laughs around the campfire were exchanged while eating our dehydrated foods.

Zach, one of the more experienced hikers, shared some advice for future backpacking trips. He suggested making a list of everything we packed, then crossing out everything we never used, to lighten our load the next time. The look on Zach’s face was priceless when he learned that deodorant was part of my supply, then we all laughed at my realization that deodorant makes no difference after days on the trail.

At the end of a busy and hard work-filled week, Matthew and I packed up camp, along with the samples, and hiked our way out of Lyell Canyon. Though excited to head home, the hike out was also bittersweet because we were leaving behind so much beauty.

Field work is a necessary component in geological sciences, and it strengthens the skills and character of anyone pursuing an education and career in this field. The experience will stick with me for the rest of my life.

Earth science major John Ayers is back in the lab this fall extracting thin sections from the samples collected in July and August and preparing them for X-ray fluorescence spectrometry. His senior thesis is designed to further the understanding of some of the complex interactions that occur below the earth’s surface.