Most of us learned in school that the Himalayan mountains were formed over millions of years as India plowed into Asia. As the two continued to pile into each other, the land in between crumpled, forming a landscape that makes mountaineers salivate. Geologists figured that as the crumpling progressed, a succession of faults opened up to accommodate the deformation, starting first in the north and then progressing one after the other as old ones froze up and new ones sprang into motion to the south.
As a graduate student at University of California, Los Angeles (UCLA) in the late 1990s, Catlos collected samples of garnet-bearing rock along the oldest, most northerly of these faults, the Main Central Thrust, which snakes 1500 miles across the Himalayas. Garnets record information about pressures and temperatures they experienced when they crystallized, as well as when they formed.
Back in the lab, Catlos sliced up the garnets. Using an instrument called an ion microprobe, she was surprised to find that the rocks were deep underground until very recently. Some had experienced temperatures of 500 degrees Celsius just a million years ago, a blink in geologic time. That translates to a rise of about 20 millimeters a year if everything was continuous.
“So it’s basically like an elevator,” she says. “Those rocks are coming up fast, fast, fast in geologic time.”
It also meant the fault is still active. Conventional wisdom suggested that this fault ground to a halt 20 million years ago.
“So the models for the Himalayas had to be rewritten,” she says. “There are still some people who like to hold on to those ideas. But we’re not the only people who have found it now.”
Snowmelt from the Himalayas flowing south in countless rivers nourishes millions of people in northern India through a system of dams. Some of those rivers cross the Main Central Thrust.
“If you think the fault is no longer active, your geologic models will tell you that building a dam in the area is just fine,” she says. “That’s a problem.”
Advisors to the Indian government are currently developing a seismic hazard map for the capital New Delhi, a megacity a few hundred miles from the Himalayas. Spurred by Catlos’ insight, they are now trying to determine what the possible shaking might be in New Delhi from a Himalayan earthquake.
For her discovery, she received the Geological Society of America’s 2006 Donath Medal, awarded to a young scientist for outstanding research that marks a major advance in the earth sciences.
From Chemist to Field Geologist
When Catlos began her college career at the University of California San Diego, she planned to become a laboratory chemist, but ended up a field geologist.
The transformation started when she took a class co-taught by Jeff Bada, a geochemist who studies amino acids delivered to Earth by asteroid and comet impacts, traces of which are found in Greenland ice cores.
“He came in and dazzled the class,” she recalls. “He challenged us to think about big questions like, What is the origin of the earth? How do mountains form? How can we get at that by using chemistry? And that was very interesting to me.”
She realized she didn’t have to spend her career stuck in a lab, she could actually make a living doing field work. She could go out and collect her own samples and apply chemistry to real world problems. Bada invited her to do an internship with him working on his Greenland ice cores.
Later, she set off to graduate school at UCLA with a plan to develop a new technique for dating minerals, but that wasn’t going so well. One day, her advisor, Mark Harrison opened up a cabinet in the hallway outside his office with 76 hand-sized rocks he’d collected in the Himalayas and said, “This is your new project. Welcome to field geology.”
“Those Himalayan rocks are the foundation,” says Catlos. “I still use the same techniques I used as a graduate student, but apply them to different places and different rock types.”
She was soon off to Nepal for her first major field trip. It seemed like everything that could go wrong went wrong. While on their way to India, her advisor’s family’s passports were stolen. They were locked up in Indira Gandhi International Airport until their status could be cleared up. After arriving in Nepal, their flights into the field kept getting canceled, so they finally had to rent a helicopter.
“The first trip to Nepal helped teach me the importance of planning,” she says, “having a plan B, knowing how to manage when things go wrong, understanding the culture, being aware, being street smart in a street that is not in the U.S.”
She’s taken many more field trips since then and she finds she learns something new that helps make the next trip more successful. The next year, she spent the entire summer in a tent on the Tibetan Plateau.
“I thought I don’t need any tent stakes, my luggage will hold the tent down,” she laughs. “And then these winds came through. I got rolled in my tent.”
As a field assistant working for another graduate student, she used a kite to take aerial photos and map the field area and she identified minerals. She got the job because the field assistant from the previous summer told his advisors he got a vaccination in the arm that gave him arthritis.
She ate lots of instant noodles, Power Bars, and dried flat bread. Occasionally they could buy meat in the countryside or locals would offer them food.
“There were a lot of challenges,” she says, “just like any international project: different food, environment, culture, weather, long drives, crazy traffic, sickness, personality conflicts, but I realized that I really enjoyed geology. I loved it.”
“If I hadn’t felt so passionately for it and got so excited about what we saw every day, it would have been miserable,” she adds. “So, that trip and the Himalayan trips, which were also challenging, reinforced that this career is the one for me.”
Over the next few summers, she did field work in northern and southern India, the Himalayas, Slovakia and Western Turkey.
Years after her first trip to the Tibetan Plateau, she was at a scientific conference and ran into the former grad student who had bowed out and given her the chance to go. He confessed that he really didn’t have a bad reaction to a shot. He just didn’t want to go.
A New Home in Texas
Catlos was an associate professor at Oklahoma State University for one year when she received a Harrington Fellowship to take a year leave of absence to do research at The University of Texas at Austin. During her fellowship, she also organized an international conference on the geology of the Aegean.
In 2008, she joined the Jackson School as an associate professor. Her first academic year on faculty was spent overseas, teaching at the Middle East Technical University in Turkey on a Fulbright Lectureship. She had already become interested in the North Anatolian Fault, a major strike slip fault with many similarities to the San Andreas she new well from growing up in California. The fellowship gave her a chance to meet Turkish researchers and learn more about the geology of the region.
“It’s a great place for geology,” she says. “Exposures of all rock types, all different types of faults. Two oceans have disappeared in Turkey, so the geology is fabulous.”
For the past year, she’s been back teaching and doing research in Austin. In spring 2011, she’ll teach a graduate course on the geology of the middle east.
“It’s going to cover everything from the origin of petroleum deposits to basic tectonics to volcanism to interesting environmental geology,” she says. “So it’s going to be a reader of new and exciting topics coming out of the Middle East.”
Topics will include the environmental impacts of recent wars in the Persian Gulf and the debate over the nature of the plate boundary between Cyprus and Israel. Her choice of topics reflects a mind constantly searching for solutions to geological puzzles.
“What is it?,” she asks. “Strike slip? Compression? Extension? It’s not been conclusively identified and it’s so bizarre that we’re living in this day and age and why don’t we know this?”
By Marc Airhart
For more information about the Jackson School contact J.B. Bird at jbird@jsg.utexas.edu, 512-232-9623.
