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Dr. Mary Chapman

Senior Scientist

Currently resides in Orangvale, CA
mchapman [at]
Areas of Expertise
Earth, Mars | Mapping, Volcanism

Research Interests

My specialties are sedimentology, stratigraphy, volcanology, petrography, geomorphology, planetary surface image analysis, geologic mapping, and general geologic field studies.  Major interests include:

  • Geologic mapping of planetary surfaces with an emphasis on Mars.
  • Sub-ice volcanism and volcano-ice interactions on Earth and Mars.
  • Catastrophic floods and fluvial materials on Earth and Mars.
  • Terrestrial analog studies of planetary features.
  • Sedimentology and stratigraphy of Mesozoic rocks on the Colorado Plateau.
  • Depositional, compositional, and petrographic aspects of volcaniclastic sediments.
  • Extinction horizons on Earth and meteoritic/climatic/volcanogenic implications.

Professional History

Volcano/Ice Interaction on Mars:

The major scientific contribution of this facet of my work has been the investigation of volcano/ice interaction on Mars and Earth, specifically the study of sub-ice volcanism features in Iceland as analogs for features observed on Mars, specifically in and around Valles Marineris and on the flanks of Elysium Mons. I'm generally recognized as expert on Martian sub-ice volcanism having lead authorship in a several papers, participated in organizing an international workshop, and being Co-Editor of a Geological Society of London text. I've been invited to give presentations at AAAS, AGU, GSL/GSA, and ESA meetings on the subject, funded by NASA to study the process on Mars and Earth, pursued the topic as the focus of my Ph.D. Dissertation "Possible Icelandic Analogs for Valles Marineris Interior Layered Deposits and Associated Outflow Channels on Mars," and produced a volcano-ice interaction page on the US Geological Survey AstroTeam website. Finally, my volcano-ice work on Earth and Mars was the basis of an invitation to produce a chapter in "Volcanic Worlds: Exploring the Solar System's Volcanoes" (Rosaly Lopes and Tracy Gregg, Eds.) written and edited solely by female Planetary Scientists.

Fluvial Processes on Mars, and Planetary Mapping:

Another major scientific contribution and an emphasis of my work have been the documentation and interpretation of fluvial materials on Mars. Fluvial deposits on Mars provide evidence for the presence of surficial, flowing water on that planet and are thus of strong interest to terrestrial and planetary geologists alike. My work in mapping these deposits in Kasei Valles and Mangala Valles---two of the largest fluvial channels on Mars---forms part of the foundation for continued work by myself and others to understand the importance of water in shaping that planet's surface. I authored the 1st three USGS 1:500,000-scale maps of Mars as landing site studies and therefore set the format for all of the successive maps. These early mapping efforts were the key for others to initiate the Mars USGS 1:500,000-scale Geologic Mapping Program and receive NASA funds for 1:500,000-scale Mars mapping efforts. One of my Kasei Valles geologic maps was also the first author-produced digital compilation of a USGS I-map and was part of a national push to produce digital products. My previous mapping and interpretation of fluvial and lacustrine landforms in Granicus Valles, and in the Elysium region also contributes to our understanding of the continuity of fluvial processes on Mars.

Colorado Plateau Studies (Terrestrial Geology):

A. I was trained as a terrestrial geologist and was involved in coal & uranium exploration, coal mining and Central Utah Project water tunnel excavation, and research studies of the Colorado Plateau for most of my early career. For example, the emphasis of my M.S. Thesis ("Depositional and Compositional Aspects of Volcanogenic Clasts in the Upper Member of the Carmel Formation, Southern Utah") was an examination of the terrestrial sedimentological and petrologic record for evidence of arc volcanism and catastrophic flooding. I wrote a GSA paper on the topic citing evidence for large-scale catastrophic flooding in southern Utah. This study is significant because it recognized, for the first time, widespread debris flows and catastrophic floods which contain large (>9 m diameter) boulders of welded rhyolitic tuff in fine-grained redbeds within two members of the Middle Jurassic Carmel Formation in southern Utah (Kane County)--this discovery provided a link between the Jurassic magmatic arc in the south-central Basin and Range area and continental strata on the Colorado Plateau. My familiarity with these types of terrestrial processes influenced the direction of my later planetary research with catastrophic flood channels and led me to jointly write a paper questioning the interpretations of Mars Pathfinder observations. I continued my involvement with plateau rocks by using my knowledge to assess geologic sites for Johnson Space Center EVA Project (1999-2009), lead planetary analog field trips in northern Arizona, and contributed to proto-type rover field engineering studies.

B. Planetary Geology also involves the field of Meteoritics (the study of bolides, meteorites, and impact craters). My terrestrial background with Mesozoic rocks and interest in the subject of Meteoritics pushed me to research the Triassic/Jurassic boundary rocks in Nevada/Utah/Arizona in order to assess the causes of Late Triassic extinctions. The T-J boundary is one of the "Big 5" extinction boundaries on Earth that has been tied to a possible bolide impact. My work the TJB has led to my 1991 volunteering with Museum of N. New Mexico Late Triassic dinosaur trackway studies (which helped to better determine the boundary location on the Plateau), and to working on a petrographic study of Snyder Quarry--a Upper Triassic Coelophysoid (Dinosauria: Theropoda) bone bed in New Mexico. The faunal age of the Snyder Quarry dinosaur die-out site (210-215 Ma) in central New Mexico that was suggested to overlap the radiometric age of the 100-km-diameter Manicouagan impact crater (214 ± 1 Ma), and large impacts are suggested to be associated with global fires, and the early dinosaur, reptile, and amphibian deaths in the quarry have been attributed to a widespread paleowildfire. My work has been to investigate the possible connections between the ancient wildfire and dinosaur deaths at the quarry. In my other petrographic and sedimentologic TJB studies, I've found possible cosmogenic (extra-terrestrial dust) spherules in the lower Moenave Formation in Nevada that may imply global aridity was responsible for extinctions near or at the Triassic-Jurassic boundary.

Outreach and Education

Over the years I have participated in numerous educational outreach events. Currently I am working on producing a Children's Science Webcomic tentatively titled "The Real People of Earth: Geo-Detectives", and both writing and illustrating the text. The work is planned as one in a series of interactive web-based (and perhaps hardcopy) animations written and drawn for children (ages 10-16) to present normally dry geological science in a more lively entertaining manner.

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