Richard O Lease, Ph.D.
Richard Lease is a Research Geologist with the Alaska Science Center in Anchorage, AK
Richard conducts framework geology research on Alaska sedimentary basins, mountain belts, landscapes, and paleoclimate. His research typically utilizes the fields of stratigraphy, tectonics, geomorphology, and geochronology. His past research focused on tectonic-climatic-geodynamic interactions during growth of the Tibetan Plateau and Central Andes.
Professional Experience
2012 – Present Research Geologist, USGS Alaska Science Center, Anchorage, Alaska
2011 – 2012 Postdoctoral Fellow, University of Tuebingen, Germany
Education and Certifications
Ph.D. 2010 University of California, Santa Barbara, CA Geology
A.B. 2005 Princeton University, Princeton, NJ Geosciences
Science and Products
Carbon Isotopes, Total Organic Carbon, Programmed Pyrolysis, Volcanic Zircon U-Pb, and Geochemistry Data from the Hue Shale, Arctic Alaska - 2024
This dataset contains results from a stratigraphic section of the Hue Shale located along the Jago River in the Arctic National Wildlife Refuge at 69.9099, -143.3947 (WGS84). Sample heights were measured with a tape measure in a continuous succession. Zircon grains from volcanic ashes were analyzed via laser ablation at either the University of California, Santa Barbara (UCSB) or the University of
Fission Track Data and Ages of Apatite and U-Pb Isotopic Data and Ages of Igneous and Detrital Zircon from Selected Rocks from the Lake Clark and Lake Iliamna Region of South-Central Alaska
This data set contains fission track data and associated ages of apatite from igneous and sedimentary rocks, U-Pb isotopic data and associated ages of zircon from a subset of the igneous rock samples, and U-Pb isotopic data and associated ages of detrital zircon from a subset of the sedimentary rock samples. All samples were collected from the region surrounding Lake Clark and Lake Iliamna in sout
Whole Rock Major and Trace Element Chemistry for Igneous and Metamorphic Rocks from the Yukon-Tanana Upland, Alaska
This data set consists of one table containing whole-rock geochemistry data for 753 igneous and metamorphic rocks from the Yukon-Tanana upland of eastern interior Alaska, collected between 2013 and 2019. All materials were analyzed by ALS Global, between 2014 and 2020, by a range of different techniques, so multiple unique entries for a given element relate to different analytical methods or prepa
Whole Rock Major and Trace Element Chemistry for Igneous Rocks from Tyonek, Lime Hills, Talkeetna, McGrath, and Lake Clark Quadrangles, Western Alaska Range, Alaska
This data release contains whole rock major and trace element data for 69 igneous rock samples collected from the Western Alaska Range between 2011 and 2012. The Series field relates to chronological units discussed in Jones et al. (2021, Geosphere) and Todd et al. (2022 IN PREP). Descriptions are from original collector notebooks and are provided here for informational purposes only.
Geochemical, Geochronologic, Rock-Eval, and Spectral Gamma Ray Data for Selected Triassic Rocks in Northwestern Alaska
This set of data files contains analyses of samples representing the Triassic Shublik and Otuk Formations in Alaska. The samples were collected from the Brontosaurus 1 well and measured stratigraphic sections at Surprise Creek and Cape Lisburne. The data set includes total organic carbon (TOC), Rock-Eval (Tmax) data, geochemical data from inductively coupled plasma-optical emission spectroscopy-ma
Whole Rock Major and Trace Element Chemistry for Igneous and Sedimentary Rocks from the Western Alaska Range, Alaska
This data release contains whole rock major and trace element data for 399 igneous and sedimentary rock samples collected from the Western Alaska Range between 1968 and 2014 and funded by the Mineral Resources Program of the U.S. Geological Survey. All materials were analyzed by ALS Global, between 2014 and 2018, by a range of different techniques, so multiple unique entries for a given element re
U-Pb Isotopic Data and Ages of Detrital Zircon and Volcanic Zircon Grains from the Torok and Nanushuk Formations, Arctic Alaska, 2021
This dataset contains U-Pb isotopic data and associated ages of zircon grains from 27 sedimentary samples and one volcanic ash sample from the Cretaceous Torok and Nanushuk Formations. Seven samples were collected from outcrop and 21 samples were collected from archived core material from oil exploration wells on the North Slope of Arctic Alaska. Zircon grains were analyzed at the University of Ca
Low-Temperature Thermochronometric Data along the Fairweather Fault, Southeast Alaska, 2015-2020
This data set provides low-temperature thermochronometric data from 15 rock samples collected along the Fairweather fault in southeast Alaska. These data are from four different analyses used to estimate cooling ages: 1) apatite (U-Th)/He, 2) zircon (U-Th)/He, 3) apatite fission-track, and 4) zircon fission-track.
Low-Temperature Thermochronometric Data from the Revelation Mountains, Western Alaska Range, 2013-2018
This data set provides low-temperature thermochronometric data from 16 rock samples collected from the Revelation Mountains area in western Alaska Range. These data are from three different analyses used to estimate cooling ages: 1) apatite (U-Th)/He, 2) zircon (U-Th)/He, and 3) apatite fission-track.
Filter Total Items: 29
Arctic Alaska deepwater organic carbon burial and environmental changes during the late Albian–early Campanian (103–82 Ma)
The middle Cretaceous greenhouse period experienced profound environmental change including episodes of enhanced global burial of organic carbon marked by carbon isotopic excursions (CIEs). However, the role and response of polar regions like the newly formed, partially enclosed Arctic Ocean Basin during middle Cretaceous carbon burial remains enigmatic. We present the first Arctic deepwater CIE r
Authors
Richard O. Lease, Katherine J. Whidden, Julie A. Dumoulin, David W. Houseknecht, Palma J. Botterell, Mark F. Dreier, Neil Patrick Griffis, Roland Mundil, Andrew Kylander-Clark, Margaret M. Sanders, John W. Counts, Jean Self-Trail, Jared T. Gooley, William A. Rouse, Rebecca A. Smith, Christina A. DeVera
Boulders modulate hillslope-channel coupling in the northern Alaska Range
Active orogens balance tectonic rock uplift with erosion, commonly via river incision coupled to landslide denudation of “threshold” hillslopes, but sediment’s role in this feedback is unclear. We report fluvial geometry, and sediment size, prevalence, and mobility across two ≤600-m-tall gneissic northern Alaska Range anticlines that sustain steep landslide-clad hillslopes but differ 10× in late P
Authors
Adrian Bender, Richard O. Lease
Fairweather transform boundary Oligocene to present orogenesis: Fairweather Range vertical extrusion and rotation of the Yakutat microplate at ca. 3 Ma
Oblique-slip along transform fault boundaries is often partitioned between a strike-slip system and thrust faults that accommodate contraction. However, topography along the Yakutat-North American transform (Fairweather fault), is asymmetric with low-terrain above active thrusts on the western, Yakutat side of the transform and high topography on the continental side with peaks >4500 m (Mount Fair
Authors
Jeff Benowitz, Richard O. Lease, Peter J. Haeussler, Terry Pavlis, Michael Mann
Geophysical constraints on continental rejuvenation in central China: Implications for outward growth of the Tibetan Plateau
Continental rejuvenation results from the tectonic reactivation of crustal structures and lithospheric reworking by mantle flow. Geochemical observations and field mapping have traditionally provided the primary evidence for the secular evolution of crustal composition and tectonic processes during continental rejuvenation. Nonetheless, the impact of continental rejuvenation on the observed presen
Authors
Yi-Peng Zhang, Pei-Zhen Zhang, Richard O. Lease, Min-Juan Li, Renjie Zhou, Bin-Bin Xu, Si-Yuan Chen, Xu-Zhang Shen, Wen-Jun Zheng, Xiao-Hui He, Wei-Tao Wang, Yue-Jun Wang
Insights into glendonite formation from the upper Oligocene Sagavanirktok Formation, North Slope, Alaska
The type locality for the upper Oligocene Nuwok Member of the Sagavanirktok Formation (Carter Creek, North Slope, Alaska, USA) contains abundant occurrence of glendonite, a pseudomorph after the calcium carbonate mineral ikaite, which typically forms in the shallow subsurface of cold marine sediments. The region during the time of Nuwok Member deposition was located at a high latitude, similar to
Authors
John W. Counts, Madeleine Vickers, Martha (Rebecca) Stokes, Whittney Spivey, Kristina Frank Gardner, Jean Self-Trail, Jared T. Gooley, Ryan J. McAleer, Aaron M. Jubb, David W. Houseknecht, Richard O. Lease, Neil Patrick Griffis, Martin S. Vickers, Kasia Śliwińska, Hannah Gail Dooley Tompkins, Adam M. Hudson
Oligocene–Miocene northward growth of the Tibetan Plateau: Insights from intermontane basins in the West Qinling Belt, NW China
Growth of the Tibetan Plateau, Earth’s broadest and highest elevation collisional system, shapes orographic barriers, reorganizes drainage networks, and influences surface erosion and sediment delivery, whose changes in space and provenance feed back to intracontinental tectonic processes. Studies of interior basins within the northern Tibetan Plateau provide new sediment accumulation, provenance,
Authors
Yi-Peng Zhang, Wei-Tao Wang, Richard O. Lease, Renjie Zhou, Yue-Jun Wang, Yong-Gang Yan, Ying Wang, Wen-Jun Zheng, Bing-Xu Liu, Zhi-Gang Li, Hao Liang, Ge-Ge Hui, Chuang Sun, Qing-Ying Tian, Bin-Bin Xu, Pei-Zhen Zhang
Rapid active thrust faulting at the northern Alaska Range front
Plate convergence rates strongly influence seismicity and mountain building inboard of convergent margins, but the distribution and kinematics of structures accommodating farfield convergence can be elusive. In interior Alaska, Yakutat microplate convergence drives late Pleistocene–recent right slip on the Denali fault, but westward-decreasing slip rates leave substantial residual Yakutat motion u
Authors
Adrian Bender, Richard O. Lease, Tammy M. Rittenour, James V. Jones
Yukon River incision drove organic carbon burial in the Bering Sea during global climate changes at 2.6 and 1 Ma
River erosion affects the carbon cycle and thus climate by exporting terrigenous carbon to seafloor sediment and by nourishing CO2-consuming marine life. The Yukon River–Bering Sea system preserves rare source-to-sink records of these processes across profound changes in global climate during the past 5 million years (Ma). Here, we expand the terrestrial erosion record by dating terraces along the
Authors
Adrian Bender, Richard O. Lease, Lee B. Corbett, Paul R. Bierman, Marc W. Caffee, James V. Jones, Douglas C. Kreiner
Biosiliceous, organic-rich, and phosphatic facies of Triassic strata of northwest Alaska: Transect across a high-latitude, low-angle continental margin
The Shublik Formation (Middle and Upper Triassic) is a mixed siliciclastic-carbonate-phosphatic unit in northern Alaska. It generated oil found in Prudhoe Bay and other accumulations and is a prospective self-sourced resource play on Alaska’s North Slope. Its distal, deeper-water equivalent—the Otuk Formation—consists largely of radiolarian chert, mudstone, and limestone and contains potential gas
Authors
Julie A. Dumoulin, Katherine J. Whidden, William A. Rouse, Richard O. Lease, Adam Boehlke, Paul O'Sullivan
Quantifying large-scale continental shelf margin growth and dynamics across mid-Cretaceous Arctic Alaska with detrital zircon U-Pb dating
Sequence stratigraphy provides a unifying framework for integrating diverse observations to interpret sedimentary basin evolution; however, key time assumptions about stratigraphic elements spanning hundreds of kilometers are rarely quantified. We integrate new detrital zircon U-Pb (DZ) dates from 28 samples with seismic mapping to establish a chronostratigraphic framework across 800 km and ~20 m.
Authors
Richard O. Lease, David W. Houseknecht, Andrew R. C. Kylander-Clark
The role of preexisting upper plate strike-slip faults during long-lived (ca. 30 Myr) oblique flat slab subduction, southern Alaska
Upper plates of subduction zones commonly respond to flat slab subduction by structural reactivation, magmatic arc disruption, and foreland basin inversion. However, the role of active strike-slip faults in focusing convergent deformation and magmatism in response to oblique flat slab subduction remains less clear. Here, we present new detrital apatite fission-track (dAFT) ages from 12 modern catc
Authors
Trevor Waldien, Richard O. Lease, Sarah Roeske, Jeff Benowitz, Paul O'Sullivan
Geomorphic expression and slip rate of the Fairweather fault, southeast Alaska, and evidence for predecessors of the 1958 rupture
Active traces of the southern Fairweather fault were revealed by light detection and ranging (lidar) and show evidence for transpressional deformation between North America and the Yakutat block in southeast Alaska. We map the Holocene geomorphic expression of tectonic deformation along the southern 30 km of the Fairweather fault, which ruptured in the 1958 moment magnitude 7.8 earthquake. Digital
Authors
Robert C. Witter, Adrian Bender, Katherine M. Scharer, Christopher DuRoss, Peter J. Haeussler, Richard O. Lease
Science and Products
Carbon Isotopes, Total Organic Carbon, Programmed Pyrolysis, Volcanic Zircon U-Pb, and Geochemistry Data from the Hue Shale, Arctic Alaska - 2024
This dataset contains results from a stratigraphic section of the Hue Shale located along the Jago River in the Arctic National Wildlife Refuge at 69.9099, -143.3947 (WGS84). Sample heights were measured with a tape measure in a continuous succession. Zircon grains from volcanic ashes were analyzed via laser ablation at either the University of California, Santa Barbara (UCSB) or the University of
Fission Track Data and Ages of Apatite and U-Pb Isotopic Data and Ages of Igneous and Detrital Zircon from Selected Rocks from the Lake Clark and Lake Iliamna Region of South-Central Alaska
This data set contains fission track data and associated ages of apatite from igneous and sedimentary rocks, U-Pb isotopic data and associated ages of zircon from a subset of the igneous rock samples, and U-Pb isotopic data and associated ages of detrital zircon from a subset of the sedimentary rock samples. All samples were collected from the region surrounding Lake Clark and Lake Iliamna in sout
Whole Rock Major and Trace Element Chemistry for Igneous and Metamorphic Rocks from the Yukon-Tanana Upland, Alaska
This data set consists of one table containing whole-rock geochemistry data for 753 igneous and metamorphic rocks from the Yukon-Tanana upland of eastern interior Alaska, collected between 2013 and 2019. All materials were analyzed by ALS Global, between 2014 and 2020, by a range of different techniques, so multiple unique entries for a given element relate to different analytical methods or prepa
Whole Rock Major and Trace Element Chemistry for Igneous Rocks from Tyonek, Lime Hills, Talkeetna, McGrath, and Lake Clark Quadrangles, Western Alaska Range, Alaska
This data release contains whole rock major and trace element data for 69 igneous rock samples collected from the Western Alaska Range between 2011 and 2012. The Series field relates to chronological units discussed in Jones et al. (2021, Geosphere) and Todd et al. (2022 IN PREP). Descriptions are from original collector notebooks and are provided here for informational purposes only.
Geochemical, Geochronologic, Rock-Eval, and Spectral Gamma Ray Data for Selected Triassic Rocks in Northwestern Alaska
This set of data files contains analyses of samples representing the Triassic Shublik and Otuk Formations in Alaska. The samples were collected from the Brontosaurus 1 well and measured stratigraphic sections at Surprise Creek and Cape Lisburne. The data set includes total organic carbon (TOC), Rock-Eval (Tmax) data, geochemical data from inductively coupled plasma-optical emission spectroscopy-ma
Whole Rock Major and Trace Element Chemistry for Igneous and Sedimentary Rocks from the Western Alaska Range, Alaska
This data release contains whole rock major and trace element data for 399 igneous and sedimentary rock samples collected from the Western Alaska Range between 1968 and 2014 and funded by the Mineral Resources Program of the U.S. Geological Survey. All materials were analyzed by ALS Global, between 2014 and 2018, by a range of different techniques, so multiple unique entries for a given element re
U-Pb Isotopic Data and Ages of Detrital Zircon and Volcanic Zircon Grains from the Torok and Nanushuk Formations, Arctic Alaska, 2021
This dataset contains U-Pb isotopic data and associated ages of zircon grains from 27 sedimentary samples and one volcanic ash sample from the Cretaceous Torok and Nanushuk Formations. Seven samples were collected from outcrop and 21 samples were collected from archived core material from oil exploration wells on the North Slope of Arctic Alaska. Zircon grains were analyzed at the University of Ca
Low-Temperature Thermochronometric Data along the Fairweather Fault, Southeast Alaska, 2015-2020
This data set provides low-temperature thermochronometric data from 15 rock samples collected along the Fairweather fault in southeast Alaska. These data are from four different analyses used to estimate cooling ages: 1) apatite (U-Th)/He, 2) zircon (U-Th)/He, 3) apatite fission-track, and 4) zircon fission-track.
Low-Temperature Thermochronometric Data from the Revelation Mountains, Western Alaska Range, 2013-2018
This data set provides low-temperature thermochronometric data from 16 rock samples collected from the Revelation Mountains area in western Alaska Range. These data are from three different analyses used to estimate cooling ages: 1) apatite (U-Th)/He, 2) zircon (U-Th)/He, and 3) apatite fission-track.
Filter Total Items: 29
Arctic Alaska deepwater organic carbon burial and environmental changes during the late Albian–early Campanian (103–82 Ma)
The middle Cretaceous greenhouse period experienced profound environmental change including episodes of enhanced global burial of organic carbon marked by carbon isotopic excursions (CIEs). However, the role and response of polar regions like the newly formed, partially enclosed Arctic Ocean Basin during middle Cretaceous carbon burial remains enigmatic. We present the first Arctic deepwater CIE r
Authors
Richard O. Lease, Katherine J. Whidden, Julie A. Dumoulin, David W. Houseknecht, Palma J. Botterell, Mark F. Dreier, Neil Patrick Griffis, Roland Mundil, Andrew Kylander-Clark, Margaret M. Sanders, John W. Counts, Jean Self-Trail, Jared T. Gooley, William A. Rouse, Rebecca A. Smith, Christina A. DeVera
Boulders modulate hillslope-channel coupling in the northern Alaska Range
Active orogens balance tectonic rock uplift with erosion, commonly via river incision coupled to landslide denudation of “threshold” hillslopes, but sediment’s role in this feedback is unclear. We report fluvial geometry, and sediment size, prevalence, and mobility across two ≤600-m-tall gneissic northern Alaska Range anticlines that sustain steep landslide-clad hillslopes but differ 10× in late P
Authors
Adrian Bender, Richard O. Lease
Fairweather transform boundary Oligocene to present orogenesis: Fairweather Range vertical extrusion and rotation of the Yakutat microplate at ca. 3 Ma
Oblique-slip along transform fault boundaries is often partitioned between a strike-slip system and thrust faults that accommodate contraction. However, topography along the Yakutat-North American transform (Fairweather fault), is asymmetric with low-terrain above active thrusts on the western, Yakutat side of the transform and high topography on the continental side with peaks >4500 m (Mount Fair
Authors
Jeff Benowitz, Richard O. Lease, Peter J. Haeussler, Terry Pavlis, Michael Mann
Geophysical constraints on continental rejuvenation in central China: Implications for outward growth of the Tibetan Plateau
Continental rejuvenation results from the tectonic reactivation of crustal structures and lithospheric reworking by mantle flow. Geochemical observations and field mapping have traditionally provided the primary evidence for the secular evolution of crustal composition and tectonic processes during continental rejuvenation. Nonetheless, the impact of continental rejuvenation on the observed presen
Authors
Yi-Peng Zhang, Pei-Zhen Zhang, Richard O. Lease, Min-Juan Li, Renjie Zhou, Bin-Bin Xu, Si-Yuan Chen, Xu-Zhang Shen, Wen-Jun Zheng, Xiao-Hui He, Wei-Tao Wang, Yue-Jun Wang
Insights into glendonite formation from the upper Oligocene Sagavanirktok Formation, North Slope, Alaska
The type locality for the upper Oligocene Nuwok Member of the Sagavanirktok Formation (Carter Creek, North Slope, Alaska, USA) contains abundant occurrence of glendonite, a pseudomorph after the calcium carbonate mineral ikaite, which typically forms in the shallow subsurface of cold marine sediments. The region during the time of Nuwok Member deposition was located at a high latitude, similar to
Authors
John W. Counts, Madeleine Vickers, Martha (Rebecca) Stokes, Whittney Spivey, Kristina Frank Gardner, Jean Self-Trail, Jared T. Gooley, Ryan J. McAleer, Aaron M. Jubb, David W. Houseknecht, Richard O. Lease, Neil Patrick Griffis, Martin S. Vickers, Kasia Śliwińska, Hannah Gail Dooley Tompkins, Adam M. Hudson
Oligocene–Miocene northward growth of the Tibetan Plateau: Insights from intermontane basins in the West Qinling Belt, NW China
Growth of the Tibetan Plateau, Earth’s broadest and highest elevation collisional system, shapes orographic barriers, reorganizes drainage networks, and influences surface erosion and sediment delivery, whose changes in space and provenance feed back to intracontinental tectonic processes. Studies of interior basins within the northern Tibetan Plateau provide new sediment accumulation, provenance,
Authors
Yi-Peng Zhang, Wei-Tao Wang, Richard O. Lease, Renjie Zhou, Yue-Jun Wang, Yong-Gang Yan, Ying Wang, Wen-Jun Zheng, Bing-Xu Liu, Zhi-Gang Li, Hao Liang, Ge-Ge Hui, Chuang Sun, Qing-Ying Tian, Bin-Bin Xu, Pei-Zhen Zhang
Rapid active thrust faulting at the northern Alaska Range front
Plate convergence rates strongly influence seismicity and mountain building inboard of convergent margins, but the distribution and kinematics of structures accommodating farfield convergence can be elusive. In interior Alaska, Yakutat microplate convergence drives late Pleistocene–recent right slip on the Denali fault, but westward-decreasing slip rates leave substantial residual Yakutat motion u
Authors
Adrian Bender, Richard O. Lease, Tammy M. Rittenour, James V. Jones
Yukon River incision drove organic carbon burial in the Bering Sea during global climate changes at 2.6 and 1 Ma
River erosion affects the carbon cycle and thus climate by exporting terrigenous carbon to seafloor sediment and by nourishing CO2-consuming marine life. The Yukon River–Bering Sea system preserves rare source-to-sink records of these processes across profound changes in global climate during the past 5 million years (Ma). Here, we expand the terrestrial erosion record by dating terraces along the
Authors
Adrian Bender, Richard O. Lease, Lee B. Corbett, Paul R. Bierman, Marc W. Caffee, James V. Jones, Douglas C. Kreiner
Biosiliceous, organic-rich, and phosphatic facies of Triassic strata of northwest Alaska: Transect across a high-latitude, low-angle continental margin
The Shublik Formation (Middle and Upper Triassic) is a mixed siliciclastic-carbonate-phosphatic unit in northern Alaska. It generated oil found in Prudhoe Bay and other accumulations and is a prospective self-sourced resource play on Alaska’s North Slope. Its distal, deeper-water equivalent—the Otuk Formation—consists largely of radiolarian chert, mudstone, and limestone and contains potential gas
Authors
Julie A. Dumoulin, Katherine J. Whidden, William A. Rouse, Richard O. Lease, Adam Boehlke, Paul O'Sullivan
Quantifying large-scale continental shelf margin growth and dynamics across mid-Cretaceous Arctic Alaska with detrital zircon U-Pb dating
Sequence stratigraphy provides a unifying framework for integrating diverse observations to interpret sedimentary basin evolution; however, key time assumptions about stratigraphic elements spanning hundreds of kilometers are rarely quantified. We integrate new detrital zircon U-Pb (DZ) dates from 28 samples with seismic mapping to establish a chronostratigraphic framework across 800 km and ~20 m.
Authors
Richard O. Lease, David W. Houseknecht, Andrew R. C. Kylander-Clark
The role of preexisting upper plate strike-slip faults during long-lived (ca. 30 Myr) oblique flat slab subduction, southern Alaska
Upper plates of subduction zones commonly respond to flat slab subduction by structural reactivation, magmatic arc disruption, and foreland basin inversion. However, the role of active strike-slip faults in focusing convergent deformation and magmatism in response to oblique flat slab subduction remains less clear. Here, we present new detrital apatite fission-track (dAFT) ages from 12 modern catc
Authors
Trevor Waldien, Richard O. Lease, Sarah Roeske, Jeff Benowitz, Paul O'Sullivan
Geomorphic expression and slip rate of the Fairweather fault, southeast Alaska, and evidence for predecessors of the 1958 rupture
Active traces of the southern Fairweather fault were revealed by light detection and ranging (lidar) and show evidence for transpressional deformation between North America and the Yakutat block in southeast Alaska. We map the Holocene geomorphic expression of tectonic deformation along the southern 30 km of the Fairweather fault, which ruptured in the 1958 moment magnitude 7.8 earthquake. Digital
Authors
Robert C. Witter, Adrian Bender, Katherine M. Scharer, Christopher DuRoss, Peter J. Haeussler, Richard O. Lease