James W. Head
2015 Penrose Medal
Presented to James W. Head
Citation by Carle M. Pieters
The Penrose Medal is awarded for outstanding original contributions and achievements that mark major advances in the science of geology. It is fitting that this year’s award highlights the evolution that has occurred in the last 50 years in the application of pure Earth geology to understanding the geology of planetary bodies. The awardee is a pioneer in applying fundamental geological principles, derived from field studies in the Appalachians, Antarctica, Hawaii, Mount St. Helens and the seafloor, to the study of the geological processes that form the geological record of the Moon, planets, satellites and small bodies. Following his field-based thesis on Devonian carbonate basin evolution in the Appalachians, Jim Head began work with NASA in the selection of Apollo landing sites, geological field training of the Apollo astronauts, Apollo mission operations, and analysis of returned materials. Most importantly he helped ensure that the returned samples could be linked to the geological characteristics of the landing sites through original research on these areas and their relation to impact basins. He continued his Earth field studies by providing geological insights into the fundamental quantification of the ascent and eruption of magma on the Earth in both the submarine and subaerial environment. He then turned to bringing this Earth geology insight to study the fundamental geological processes that form the geological record of the crusts of other planetary bodies, with basic research in processes of ascent and eruption of magma and the interpretation of surface features on the Moon, Mars, Venus and Mercury. Involvement in United States, Soviet Union, European Space Agency and international space missions brought original contributions on the tectonic styles exhibited by the terrestrial planets and the nature and history of the impact cratering record. A major goal was to elucidate the first half of planetary geologic history to provide important perspective on the “missing chapters” in Earth geologic history. He has spent five field seasons in the Antarctic Dry Valleys, documenting cold-environment geological processes and applying them to interpreting the climate history of the planet Mars. Returning to his field roots, he has also provided field insight into guidelines for geologic unit definition and characterization, with application to remote mapping of the Moon, Mercury and Venus. This year’s Penrose Medalist, Prof. James W. Head, has directly brought terrestrial geological insight into the fields of planetary materials, geophysics, atmospheres, remote sensing, and climate studies, through outstanding original contributions and achievements that mark major advances in the science of geology.
It is a great honor to receive the Penrose Medal “for outstanding original contributions and achievements that mark major advances in the science of geology.” It has been a great adventure to be involved in the evolution that has occurred in the last 50 years in the application of pure Earth geology to understanding the geology of planetary bodies. As a geologist, it has been very important to apply fundamental geological principles, derived from field studies in Antarctica, Hawaii, Mount St. Helens and the seafloor, to the study of the geological processes that form the geological record of the Moon, planets and satellites.
I want to acknowledge the pivotal role in my career played by my undergraduate mentors at Washington and Lee University, Ed Spencer and Sam Kozak. These individuals both taught and inspired me with detailed field studies in the Appalachians and Montana, in exploring critical questions about the history of the Earth, and in thinking about the planets. In graduate school at Brown University, Leo Laporte and Tim Mutch engaged and excited me in using stratigraphy to unravel Earth history and paleoenvironments. Tim Mutch encouraged me to look up at the planets, with my feet planted firmly in the geology of our Home Planet, Earth, and encouraged me to explore and look beyond the horizon. At NASA Noel Hinners and Farouk El Baz taught me to be a systems engineer, a perspective that has been critical to my scientific career. I am greatly indebted to many mentors during the Apollo Lunar Exploration Program in the great adventure of exploring the Moon, including Apollo Astronauts Dave Scott, John Young and Jack Schmitt, who have remained close friends to this day.
The extensive lunar database provided by the very successful Apollo Program enabled application of geological principles and processes to lunar problems. It has been an extreme pleasure to work with Lionel Wilson on the basic framework for the generation, ascent and eruption of magma on the Moon and apply these to the assessment of the lunar volcanological record. The geological record provided insight into the tectonic structure of the Moon, and its early thermal evolution. Working with Sean Solomon, we established the basic framework of cross-cutting and superposition relationships of geologic tectonic structures for each of the major impact basins, and used the ages and spacing to determine lithospheric thickness as a function of time over the Moon, further characterizing the Moon as a “one-plate planet.”
Apollo also showed that impact cratering was a fundamental geological process in early planetary history. The importance of huge impact basins in the crustal and lithospheric evolution of the Moon led us to document the evidence of geological and thermal effects of basin formation, and the influence of the changing thermal state of the Moon on basin formation and relaxation.
During this time it was very important to continue Earth geological field studies with emphasis on effusive and explosive eruptions in subaerial (Hawaii, Mount St. Helens) and submarine (Seamount 6, East Pacific Rise, Loihi and the Gorda Ridge) environments. Working with Lionel Wilson and colleagues, the basic principles of ascent and eruption were developed and the relationships between observed landforms and key physical volcanology parameters were outlined. We tried to provide key links between basic geological observations and the process of magma ascent and eruption in submarine explosive volcanism and in a new model for Earth kimberlite eruptions.
Exploration of Earth’s “twin” planet, Venus provided huge surprises. Working with Earth-based radar images, US Pioneer-Venus data, Soviet scientists and as a guest investigator on the Soviet Venera 15-16 missions, lander panoramas and radar images and altimetry of the surface were analyzed. Geological processes forming and modifying Venus were mapped and documented, and the early outlines of the geological history emerged. Participation in the Magellan Mission led to a synthesis of the globally observed geology and setting of the full array of volcanic features. We outlined the basic principles of magma ascent and eruption in the unusual high-pressure, high-temperature Venus environment, and enabled landforms to be interpreted in a physical volcanology context. Working with colleagues Alexander Basilevsky and Mikhail Ivanov, we documented the major geological units on Venus and their stratigraphic relationships, leading to the geological mapping of several quadrangles and a global geological map of Venus.
It has been a great pleasure to be involved in the MESSENGER mission to Mercury and gain substantial insights into volcanism, tectonism, geochemistry and chronology of this enigmatic planet. Participation in the Galileo Mission to Jupiter and its satellites offered an opportunity to apply basic geological principles to volcanically active Io, and the very different icy worlds of Europa, Ganymede and Callisto. Analysis of small solar system bodies involved participation as a Guest Investigator in the Soviet Phobos Missions and in the analysis of asteroids targeted during the Galileo mission (Gaspra Ida, Dactyl). We were able to gain new insights into the formation of surface geological features and the nature of cratering on small bodies. Most recently, work has focused on the nature of the grooves on Phobos and the amount of Mars crater ejecta that might be in the soil of Phobos.
Many geological features seen on Mars have been attributed to cold-climate and perhaps periglacial processes, and collaboration with glacial geologist David Marchant led to a very successful series of field seasons in the Antarctic Dry Valleys during which time the basic outlines of microclimate zones there were documented and applied to developing criteria for their recognition on Mars. At the same time, contacts were developed and collaboration established with Francois Forget and his colleagues (prominent climate modelers in the field of Martian GCMs and their use in assessing the climate history of Mars); new aspects of Noachian GCMs have been developed to help clarify the overall evolution of the climate of Mars.
It has been a great pleasure to help to bring terrestrial geological insight into the fields of planetary materials, geophysics, atmospheres, remote sensing, and climate studies, through the help of many, many individuals, both teachers and students.