Interest in Papago rocks grows into new discoveries
Editor's note: This story is part of a series of student profiles that are part of our December 2015 commencement coverage.
When Ron Dorn, professor and instructor of Emily Kaba’s course in Landform Processes, began talking about “geomorphology puzzles,” and especially the odd-looking rocky hills just north of campus in Papago Park, Emily Kaba was intrigued.
Kaba came to ASU from Dubai in the United Arab Emirates, where she’d been born and raised. With a multilingual family in which she learned Norwegian from her mother and Arabic from her father, Emily attended a British school. As a senior in high school under the British system, she chose three topics to focus her studies on: theater, performance arts and geography.
“In geography, we were expected to conduct research, and I was surprised at how much I enjoyed it,” said Kaba. She chose to focus on water sustainability — but still intended to focus on theater and performance arts in her college studies, until she visited her brother, who was at that time studying at ASU.
“I loved the ASU campus and the desert environment, and ended up the next year as a freshman here, majoring in geography,” Kaba said.
As a sophomore, she had an opportunity to do an internship with ASU’s Decision Center for a Desert City, where she researched the process of decision making within Arizona’s irrigation districts.
It was that same semester that Dorn introduced her to the many questions that exist about landforms and how they came to be. He told her that the rocks that form the rounded caves of the Papago Hills — with their small clusters of smooth holes — are called “tafoni,” and that scientists don’t fully understand how they form. He told her about a few hiking trails where she could look at tafoni in real life — and along with the trails, Kaba discovered her honors thesis research path.
Kaba was able to train to use one of ASU’s powerful electron microprobes. She gathered samples of tafoni from Papago Park as well as Picketpost Mountain near Superior, Arizona, and on a trip home, was also able to collect samples from a site in neighboring Oman. She mastered the art of preparing the samples for the electron microprobe and analyzing the microprobe’s images together with results of X-ray analysis — processes more typically undertaken as part of doctoral or post-doctoral studies.
Her observations and analysis began to reveal some pieces of the puzzle. In all three locations, chemical and physical processes work together to erode rock into the unique tafoni surface. The processes in the samples from Papago Park and Oman appeared to be quite similar — but although the Picketpost Mountain rocks look very similar, they appeared to have a very different history.
Another key finding is that processes operating on the tiniest components of the rock influence those operating at a slightly larger scale, and these in turn generate the tafoni forms that we see.
These findings are novel enough to be published, and writing at least one paper to submit to a scientific journal is high on Kaba’s post-graduation to-do list.