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HISTORY AND PHILOSOPHY OF GEOLOGY DIVISION STUDENT AWARD

Student Award for 2011 to Margaret Rosenburg

 

Citation by Bill Brice: Margaret Rosenburg is a PH.D. candidate at California Institute of Technology in Planetary Science, with a minor in the history and philosophy of science.  As part of her thesis on the topography and surface processes of the moon, she examined the work of G. K. Gilbert (1843-1918) and his ideas about the origin of Arizona's Meteor Crater, and the influence this and later work had on others in the field, especially as it pertained to the creation of lunar craters.

 

In 1890, Gilbert undertook a study of the Arizona crater and came to the conclusion that some kind of steam explosion, not meteorite impact, was the mechanism responsible for the feature.  Several people took exception to Gilbert's ideas, notably Daniel M. Barringer, whose name is now associated with the crater.  Barringer provided counter evidence which strongly supported an impact origin, but Gilbert did not respond.  This created uncertainty within the scientific community as to its origin and the debate lasted for decades.  Although he did not re-visit his ideas about the Arizona crater, Gilbert, instead, turned his attention to the lunar craters, even experimenting with projectiles and soft sand to compare the shapes of the lunar craters to what appeared in the sand after it was hit by a projectile.  This study, truly cross-disciplinary in character, led him to conclude that the impact theory best fit the observations and his experimental data.  Oddly he did not go back and re-examine his ideas regarding the Arizona crater in light of these findings; perhaps a topic for further work.

 

Ms. Rosenburg's analysis of what happened next shows that Gilbert's ideas were welcomed neither by the geologists nor the astronomers, for each group felt that he was working too far outside his accepted area and this led him "…dangerously close to speculation."  As she described the situation, it was a clash of two different philosophical approaches to doing science.  As Ms. Rosenburg put it, “Astronomers, comfortable working purely from visual observations of the surface, tended to propose explanations based on terrestrial analogs,…  The field of geology, on the other hand, was more firmly rooted in the inductive method of gathering samples, and many geologists rejected any hypothesis for crater formation as mere speculation in the absence of enough empirical data.”   Her study nicely demonstrates that a person’s reputation in one area of study does not necessarily extend into a different one.

 

Ms. Rosenburg's work is a fine example of integrating the historical development of ideas into a modern study.  She has shown that from the examination of these past conflicts universal themes emerge that have timeless application.

 

The History & Philosophy Division of the Geological Society of America is pleased to present its Student Award for 2011 to Ms. Margaret Rosenburg of the California Institute of Technology.

 

ABSTRACT: G.K. Gilbert: Discipline Boundaries and the Impact Hypothesis

 

The impact hypothesis for the formation of craters found on the Earth, the Moon, and other planetary bodies has had a long and eventful history from the time it was first proposed in the seventeenth century to the present day, where it forms a pillar of the modern discipline of planetary science. This record has been summarized by several historians of science, particularly with the goal of determining reasons for the apparent delay in acceptance of the theory. Many factors have been suggested to have contributed to a continued skepticism of the impact hypothesis throughout the late nineteenth and twentieth centuries, ranging from an incomplete understanding of impact physics to the influence of specific scientific authority figures and their personalities. In this paper, I focus on an understudied aspect of the story: the interdisciplinary conflict between astronomers and geologists and the tensions generated by early cross-disciplinary studies of lunar and terrestrial craters. Each field possessed its own concept of "good science," its own methods, professional hierarchies, and organizations. A successful application of geological principles to the craters of the Moon--an astronomical body--required not only interaction with the representatives of each discipline, but compromise as well. The mechanics of achieving such compromise were not straightforward, and neither were they always understood by those directly involved. Here I use the works of G. K. Gilbert (1843-1918) on lunar craters and Meteor Crater in Arizona to trace the attitudes of both communities regarding theories of crater formation and the emergence of researchers equipped to apply the methods of both disciplines.

 

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