Andrea Balbas

Andrea Balbas
California Institute of Technology

2018 Doris M. Curtis Outstanding Woman in Science Award

Presented to Andrea Balbas

Citation by Peter U. Clark

Andrea Balbas is a remarkable person who has proven that she has what it takes to succeed at the highest level – she has all the makings of becoming a real star. She has an unusually mature perspective and understanding of the “big” questions and knows how to go about addressing them in truly novel ways. She is one of the most creative students I have encountered, frequently thinking “outside of the box” in her quest for new and exciting research questions. She is an exceptional and exceptionally hard-working scientist with a wide-ranging scientific tool kit. Given the breadth and depth of her dissertation research as well as her high intellect, enthusiasm for teaching, and personal drive to serve as a role model, especially for underrepresented minorities and women, Andrea embodies the very essence of the Doris Curtis Outstanding Woman in Science Award.

For her dissertation research, Andrea worked on several outstanding questions regarding timing of large variations in the geomagnetic field and various aspects of cosmogenic nuclides including the controls on their production and fluxes in the atmosphere and their application to one of the greatest geological stories ever told. Her first project developed a high-precision 40Ar/39Ar geochronology from the Galapagos Islands that constrained the age of a geomagnetic excursion known as the Santa Rosa excursion. Previously interpreted to be the Matayama-Brunhes (M-B) reversal, Andrea obtained new high-precision 40Ar/39Ar ages that demonstrated that the excursion was older, with the newly derived age (925.1 ± 4.5 ka) suggesting it recorded the Santa Rosa excursion that had previously only been identified at higher latitudes. This result was only possible because her new chronology represented a vast improvement in accuracy and precision over previous dating from the site. The record from the Galapagos suggests an 86% reduction in absolute field intensity in the equatorial region. These data are particularly significant in suggesting that the Santa Rosa excursion was a large and apparently short-lived (<3 kyr) geomagnetic anomaly, illustrating the potential for the geodynamo to alter the geomagnetic field in less than a few millennia.

Andrea next worked in Tahiti, where she completed the field planning, fieldwork, field mapping and sample collection of 13 lava flows that spanned the M-B reversal. Andrea analyzed 46 samples for 40Ar/39Ar ages from 13 lava flows that bracket and precede the M-B reversal, with 2 s errors ranging from ~3.5 ka to 5 ka on ages ranging from 857 ka to 771 ka – a remarkable achievement. Because of these high-precision results, Andrea was able to conclude that there were several rapid and short-lived changes in field orientation up to 33,000 years prior to the M-B reversal that occurred during an extended period of reduced field strength recorded in sediments. She then used a simple stochastic model to show that these rapid polarity changes are highly attenuated in sediment records with low sedimentation rates. This prolonged 33,000-year period of reduced field strength and increased geomagnetic instability supports models that show frequent centennial-to-millennial scale polarity changes in the presence of a strongly weakened dipole field. This research has tremendous implications for geodynamo behavior as well as for understanding the age of the reversal, which serves as a critical stratigraphic constraint for latest Cenozoic events.

Andrea’s last major research project for her Ph.D. involved using, for the first time, cosmogenic nuclides to date the geomorphic features that formed in association with the late-Pleistocene Missoula floods, which are the largest floods known from the geologic record, with freshwater fluxes equivalent to the combined flux from all of the world’s rivers today. Although it is now clear that there were multiple late Pleistocene floods, nearly all of our understanding of the age of the floods comes from rhythmically bedded slackwater deposits that, while constraining the duration of the interval of flooding episodes, provide no information on the amplitudes and routes taken by floods at different times. Such information can only be established by constraining the age of the flood-landscape elements that comprise the Channeled Scabland and other parts of the flood path, but this remains largely unknown because of the dearth of organic material for radiocarbon dating associated with these landscapes. Andrea addressed this question by dating flood landscapes with cosmogenic nuclides, collecting samples from across the swath of the flood reach, from eastern Washington to central Oregon. Andrea obtained 32 10Be ages on flood features and the terminal moraine of the Cordilleran Ice Sheet that influenced flood routing. By virtue of having developed the first comprehensive chronology of Missoula flood history, her work represents the next great chapter in developing and refining our understanding of this amazing part of Earth’s history.

In summary, Andrea Balbas represents an outstanding citizen-scholar who has demonstrated academic excellence and exceptional potential for research activity. In my experience with some very bright and successful graduate students, Andrea ranks among the very best in her promise to make important and significant research contributions in the earth sciences. Her strengths are many, and include her enthusiasm, her creativity, her self-motivation, her independence in getting work done, her attention to details, and her expertise in field and laboratory work. Intellectually, Andrea is on par with the brightest graduate students I have encountered, and she has demonstrated an outstanding ability to critically evaluate hypotheses as well as to develop new and important ideas. She is also a model citizen and colleague, always being available to help fellow students with their research as well as contribute in numerous ways to college activities. Andrea is a wonderful scientist and colleague who has already conducted groundbreaking research for her dissertation and offers tremendous promise for continued success both in research and in mentoring of women and minorities. She is truly an ideal recipient of the Doris Curtis Outstanding Woman in Science Award.

2018 Doris M. Curtis Outstanding Woman in Science Award — Response by Andrea Balbas

Thank you Peter for your kind and generous words as well as your years of friendship and loyalty. I’m overwhelmed and elated to be selected as the Doris M. Curtis Outstanding Woman in Science, especially by the Geological Society of America that declares their unwavering support for women in the geosciences. I am deeply grateful that they have created such an award that highlights the hard-earned achievements of female scientists.

My graduate studies revolved around age determination methodologies. Geochronology is about the timing of geological events. However, its aim is to tell us more than simply “when” something occurred. It informs other important questions about geologic processes, such as the order in which and how fast events occurred, and if two seemingly disparate events actually are concurrent in time. Ultimately, it aids in answering the fundamental question of why something occurred. I love such work because it allows me to test bold hypotheses that address big picture geologic questions. I am grateful to have been guided by Peter Clark and Anthony Koppers during my graduate tenure at Oregon State University. This graduate research would not have been possible without generous support from the National Science Foundation and Ford Foundation. During this exciting time, I wrote three papers on the timing and dynamics of paleomagnetic anomalies and megaflood processes.

We have not yet achieved equality for women in the geosciences but beacons of support surround us. There is grace in accepting the differences of others and dignity in valuing such diversity. There is an abundance of dignity in the loyalty, compassion, empathy and integrity required to celebrate and honor the contributions made by those that do not share one’s own lifestyle, gender, race or socio-economic status. These attributes can’t be acquired by any means other than courageous choice. Such are the choices that heroes make and I have been beyond fortunate to be supported by such courageous people throughout my career thus far. This award is theirs. Any scientific contributions I have made are a direct result of their selflessness and generosity. These people have helped me become a better scientist and made my life better; Dennis Kent, Rob Coe, Brent Dalrymple, Robert Duncan, Robert Butler, Jim O’Connor, Victor Baker, Bruce Bjornstad, Hannes Brueckner, Cecilia McHugh, Josh Cuzzone, Aaron Barth, Brendan Reilly, Shaun Marcott, Julia Rosen, Edward Brook, Anthony Koppers, Joseph Stoner, Peter Clark, Ashanti Johnson, Cindy Weinstein, Felicia Hunt, and Kevin Konrad.

I am tremendously grateful and honored to be named the Doris M. Curtis Outstanding Woman in Science. I hope I can continue to conduct such exciting research about our amazing planet with such wonderful people. Thank you from the bottom of my heart.