Mark, D.F., P.R. Renne, R. Dymock, V.C. Smith, J.I. SImon, L.E. Morgan, R.A. Staff, and B.S. Ellis, 2017. High-precision 40Ar/39Ar dating of pleistocene tuffs and temporal anchoring of the Matuyama-Brunhes boundary. Quaternary Geochronology 39, 1-23, https://doi.org/10.1016/j.quageo.2017.01.002.
Leah E Morgan, Ph.D.
Biography
I joined the 40Ar/39Ar geochronology lab at the USGS in Denver, Colorado as a research geologist in 2015. I was previously a Marie Curie postdoctoral fellow at the Scottish Universities Environmental Research Center and at the Vrije Universiteit Amsterdam. I received a PhD from the University of California at Berkeley in 2009, and a BA from Carleton College in 2004. I was born and raised in Vermont.
I have worked on a range of applications and method development issues in 40Ar/39Ar geochronology. Applications have largely focused on questions in paleoanthropology and the geologic timescale. Method development projects include developing metrologically traceable systems for measuring absolute quantities of 40Ar and 40K, and the design of a mobile neutron source for the future in situ deployment of 40Ar/39Ar capabilities on planetary surfaces.
Education
- Ph.D. Earth & Planetary Science, University of California at Berkeley, 2009
- B.S. Geology, Carleton College, 2004
Professional Experience
- 2015-present, Research Geologist, U.S. Geological Survey
- 2014, Visiting Assistant Professor, Geology Department, Carleton College
- 2011-2014, Marie Curie Postdoctoral Fellow, Scottish Universities Environmental Research Center, University of Glasgow, Scotland
- 2009-2011, Marie Curie Postdoctoral Fellow, Vrije Universiteit Amsterdam, The Netherlands
Affiliations
- 2018-present, Affiliate Faculty, Colorado School of Mines, Golden, CO
Academic and Professional Service
- 2021, co-Chair, Gordon Research Conference on Geochronology
- 2019, vice-Chair, Gordon Research Conference on Geochronology
- 2018-2019, Chair and Founder, Geochronology Division of the Geological Society of America
- 2019-present, Advisory Member, Committee for the Stratigraphy and Chronology Commission, International Union for Quaternary Research
- 2018-present, Steering Committee Member, EarthRates Research Coordination Network
USGS Service
- 2020-present, USGS TRIGA Reactor Operating Committee
- 2017-present, USGS Radiation Safety Committee
- 2016-present, USGS Rocky Mountain Science Seminar Series Convener
- 2018-2020 GGGSC Early Career Advisory Team, GGGSC
Awards
- 2019, USGS Superior Service Award
Science and Products
Date published: May 29, 2020
Status: Active Argon Geochronology
This project supports the USGS argon geochronology laboratory in Denver. The USGS 40Ar/39Ar geochronology laboratory is a state-of-the-art research facility for determining absolute ages of minerals and rocks. The 40Ar/39Ar laboratory contributes critical geochronology to individual USGS research projects and to partners in academia and other Federal...
Date published: October 4, 2019
Status: Active Geologic Framework of the Intermountain West
The Geologic Framework of the Intermountain West project was launched with the goal of producing a new digital geologic map database and 3D geologic model of a transect from the Rio Grande rift to the Basin and Range, based on a synthesis of existing geologic maps with new targeted new mapping, subsurface data, and other data sets. This database will integrate disparate map data, resolve...
Contacts: Joseph Colgan, Ren Thompson
Date published: May 8, 2019
Status: Active Serving the U.S. Geological Survey’s geochronological data
Geochronological data provide essential information necessary for understanding the timing of geologic processes and events, as well as quantifying rates and timescales key to geologic mapping, mineral and energy resource and hazard assessments. The USGS’s National Geochronological Database (NGDB) contains over 30,000 radiometric ages, but no formal update has occurred in over 20 years. This...
Contacts: Amy Gilmer, Leah E Morgan, Ph.D., Michael Cosca, Adam M Hudson, James Paces, Joseph Colgan
Attribution: Community for Data Integration (CDI)
Date published: April 9, 2021
Argon data for Hugub Area, Kesem-Kebena-Dulecha, Ethiopia
Tephra samples were collected by Leah Morgan (now at the U.S. Geological Survey (USGS)) from the Hugub Area, Kesem-Kebena-Dulecha, Afar, Ethiopia. Sanidine grains were separated from the bulk sample and analyzed by argon geochronology at the Scottish Universities Environmental Research Centre, Scotland.
Date published: July 7, 2020
Argon data for Klamath Mountains
This dataset accompanies planned publication '40Ar/39Ar geochronology of hydrothermal activity related to orogenic gold mineralization in the Klamath Mountains, California, U.S.A.'. The Ar/Ar data are for samples that record the mineralization of the area. The geochronology provides time constraints for the mineralization studied in the manuscript. Samples were collected from the Klam
Date published: June 24, 2020
Argon data for Nepal
This dataset accompanies planned publication 'Determining fault geometry through the transport-parallel distribution of thermochronometer cooling ages'. The Ar/Ar data is for samples that record the thermal history of the area. The geochronology provides time constraints for the thermal histories studied in the manuscript. Samples were collected from Nepal, overseen by Nadine McQuarrie %2
Date published: June 19, 2020
Argon data for Amazon Craton
This dataset accompanies planned publication 'Genesis of early Neoproterozoic gold deposits, southwestern Amazon Craton, western Brazil'. The Ar/Ar data is for samples that record the mineralization of the area. The geochronology provides time constraints for the mineralization studied in the manuscript. Samples were collected from the Amazon Craton region, and collection was done by
Date published: June 5, 2020
Argon data for Central Anatolian Ophiolite
This dataset accompanies planned publication 'Conditions, mechanisms, and timing of high-grade metamorphism and ductile deformation of the southern segment of the Central Anatolian Ophiolite'. The Ar/Ar data are for samples that record the metamorphic deformation of the ophiolite. The geochronology provides time constraints for the deformation studied in the manuscript. Samples were col
Date published: June 5, 2020
Argon data for Yellow Pine
This dataset accompanies planned publication 'Timing of Hydrothermal Alteration and Au-Sb-W Mineralization, Stibnite-Yellow Pine District, Idaho'. The Ar/Ar data is for samples that record the mineralization of the area. The geochronology provides time constraints for the mineralization studied in the manuscript. Samples were collected from the Yellow Pine region, and collection was d
Date published: June 5, 2020
Argon data for Central Andes (Domeyko Range, Chile)
This dataset accompanies planned publication 'Gondwanan inheritance on the building of the western Central Andes (Domeyko Range, Chile): Structural and thermochronological approach (U-Pb and 40Ar-39Ar)'. The Ar/Ar data is for samples that record the sedimentation of the area. The geochronology provides time constraints for the sedimentation studied in the manuscript. Samples wer
Date published: May 21, 2020
Argon data for Southern Patagonian Andes
This dataset accompanies planned publication 'Detrital record of the Late Oligocene – Early Miocene mafic volcanic arc in the Southern Patagonian Andes (~51°S) from single-clast geochronology and trace element geochemistry'. The Ar/Ar data is for samples that record the detrital sedimentary record of the basin. The geochronology provides time constraints for the sedimenta
Attribution: Geology, Geophysics, and Geochemistry Science Center
Date published: October 7, 2019
Argon geochronology data for eastern Bhutan
This dataset accompanies publication 'The influence of foreland structures on hinterland cooling: evaluating the drivers of exhumation in the eastern Bhutan Himalaya'. The Ar/Ar data provides time constraints for the cooling of rocks in the study area.
Date published: April 19, 2019
Data to accompany U.S. Geological Survey Data Series 1099: Petrographic, geochemical and geochronologic data for Cenozoic volcanic rocks of the Tonopah, Divide, and Goldfield Mining Districts, Nevada
This dataset is the assembled analytical results of geochemical, petrographic, and geochronologic data for samples, principally those of unmineralized Tertiary volcanic rocks, from the Tonopah, Divide, and Goldfield mining districts of west-central Nevada. Much of the data presented here for the Tonopah and Divide districts are for samples collected by Bonham and Garside (1979) du
Date published: April 1, 2019
Argon geochronology data forMultiproxy Cretaceous-Paleogene boundary event stratigraphy: an Umbria-Marche basin-wide perspective
This dataset accompanies publication 'Multiproxy Cretaceous-Paleogene boundary event stratigraphy: an Umbria-Marche basin-wide perspective'.
Attribution: Geology, Geophysics, and Geochemistry Science Center
Date published: January 31, 2019
Argon geochronology data for La Garita caldera
This dataset accompanies publication 'A supervolcano and its sidekicks: A 100 ka eruptive chronology of the Fish Canyon Tuff and associated units of the La Garita magmatic system', in review in Geology, which analyzed eruptive products from the La Garita caldera.
Year Published: 2021
Gondwanic inheritance on the building of the western Central Andes (Domeyko Range, Chile): Structural and thermochronological approach (U-Pb and 40Ar-39Ar)
Tectonics inheritance controls the evolution of many orogens. To unravel the role of the Gondwanan heritage (late Paleozoic to Triassic) over the building of the Central Andes in northern Chile (Domeyko Range), we performed detrital U‐Pb zircon and 40Ar/39Ar muscovite geochronology along with structural analyses (kinematics and structural...
Espinoza, Mauricio; Oliveros, Veronica; Vasquez, Paulina; Giambiagi, Laura; Morgan, Leah E.; Gonzalez, Rodrigo; Solari, Luigi; Bechis, Florencia
Year Published: 2021
Interpreting and reporting 40Ar/39Ar geochronologic data
The 40Ar/39Ar dating method is among the most versatile of geochronometers, having the potential to date a broad variety of K-bearing materials spanning from the time of Earth’s formation into the historical realm. Measurements using modern noble-gas mass spectrometers are now producing 40Ar/39Ar dates with analytical uncertainties of ∼0.1%,...
Schaen, Allen J.; Jicha, Brian R.; Hodges, Kip V.; Vermeesch, Pieter; Stelten, Mark E.; Mercer, Cameron M.; Phillips, David; Rivera, Tiffany; Jourdan, Fred; Matchan, Erin L.; Hemming, Sidney R.; Morgan, Leah E.; Kelley, Simon P.; Cassata, William S.; Heizler, Matt T.; Vasconcelos, Paulo M.; Benowitz, Jeff A.; Koppers, Anthony A.P. ; Mark, Darren F.; Niespolo, Elizabeth M.; Courtney J. Sprain; Hames, William E.; Kuiper, Klaudia F.; Turrin, Brent D.; Renne, Paul R.; Ross, Jake; Nomade, Sebastian; Guillou, Hervé; Webb, Laura E.; Cohen, Barbara A.; Calvert, Andrew T.; Joyce, Nancy; Ganderød, Morgan; Wijbrans, Jan; Ishizuka, Osamu; He, Huaiyu; Ramirez, Adán; Pfänder, Jörg; Lopez-Martínez, Margarita; Qiu, Huaning; Singer, Brad S.
Year Published: 2020
Constraining central Himalayan (Nepal) fault geometry through integrated thermochronology and thermokinematic modeling
Constraining the subsurface structural geometry of the central Himalaya continues to prove difficult, even after the 2015 Gorkha earthquake and the resulting insights into the trajectory of the Main Himalayan thrust (MHT). To this end, we apply a thermokinematic model to evaluate four possible balanced cross section geometries based on three...
Ghoshal, Surydoy; McQuarrie, Nadine; Robinson, Delores; Adhikari, D.P.; Morgan, Leah E.; Ehlers, Todd A.
Year Published: 2020
Conditions and timing of high-grade metamorphism and ductile deformation of the southern segment of the Central Anatolian Ophiolite
Ophiolitic fragments scattered over a wide area of Central Anatolia exhibit varying degrees of metamorphism, from unmetamorphosed to upper amphibolite facies, although geochemical similarities suggest they are all part of the Central Anatolian Ophiolite (CAO). Magmatic crystallization of oceanic crust in the CAO at ~ 91 Ma coincided with high...
Radwany, Molly S.; Morgan, Leah E.; Whitney, Donna L.
Year Published: 2020
Detrital record of the late Oligocene – Early Miocene mafic volcanic arc in the southern Patagonian Andes (~51 °S) from single-clast geochronology and trace element geochemistry
Retroarc foreland basins are important archives of continental arc magmatism and upper plate deformational processes that control the evolution of continental lithosphere. However, resolving source areas in foreland basin infill dominated from mixed mafic and recycled sediment using conventional methods such as detrital zircon geochronology poses...
VanderLeest, Rebecca A; Fosdick, Julie C; Leonard, Joel S; Morgan, Leah E.
Year Published: 2019
Geologic map of the Poncha Pass area, Chaffee, Fremont, and Saguache Counties, Colorado
This report presents a 1:24,000-scale geologic map, cross sections, and descriptive and interpretative text for the Poncha Pass area in central Colorado. The map area is irregular in shape, covering all of one 7 ½' quadrangle (Poncha Pass) and parts of five others (Mount Ouray, Maysville, Salida West, Salida East, and Wellsville). The map...
Minor, Scott A.; Caine, Jonathan Saul; Ruleman, Chester A.; Fridrich, Christopher J.; Chan, Christine F.; Brandt, Theodore R.; Holm-Denoma, Christopher S.; Morgan, Leah E.; Cosca, Michael A.; Grauch, V. J.Attribution: Geosciences and Environmental Change Science Center, Geology, Geophysics, and Geochemistry Science Center, Geology, Minerals, Energy, and Geophysics Science Center, Region 7: Upper Colorado Basin
View Citation
Minor, S.A., Caine, J.S., Ruleman, C.A., Fridrich, C.J., Chan, C.F., Brandt, T.R., Holm-Denoma, C.S., Morgan, L.E., Cosca, M.A., and Grauch, V.J.S., 2019, Geologic map of the Poncha Pass area, Chaffee, Fremont, and Saguache Counties, Colorado: U.S. Geological Survey Scientific Investigations Map 3436, 4 sheets, scale 1:24,000, https://doi.org/10.3133/sim3436.
Year Published: 2019
Multiproxy Cretaceous-Paleogene boundary event stratigraphy: An Umbria-Marche basin-wide perspective
The complete and well-studied pelagic carbonate successions from the Umbria-Marche Basin (Italy) permit the study of the event-rich stratigraphical interval around the Cretaceous-Paleogene (K-Pg) boundary (e.g., Deccan volcanism, boundary impact, Paleocene recovery and climate). To test the robustness of various proxy records (bulk carbonate δ13C...
Sinnesael, Matthias; Montanari, Alessandro; Frontalini, Fabrizio; Coccioni, Rodolfo; Gattacceca, Jerome; Snoeck, Christophe; Wegner, Wencke; Koeberl, Christian; Morgan, Leah E.; de Winter, Niels; DePaolo, Donald J.; Claeys, Philippe
Year Published: 2019
The influence of foreland structures on hinterland cooling: evaluating the drivers of exhumation in the eastern Bhutan Himalaya
Understanding, and ideally quantifying, the relative roles of climatic and tectonic processes during orogenic exhumation is critical to resolving the dynamics of mountain building. However, vastly differing opinions regarding proposed drivers often complicate how thermochronometric ages are interpreted, particularly from the hinterland portions of...
McQuarrie, Nadine; Eizenhofer, Paul R.; Long, Sean P.; Tobgay, Tobgay; Ehlers, Todd A.; Blythe, Ann; Morgan, Leah E.; Gilmore, Michelle; Dering, Gregory M.
Year Published: 2019
Petrology of volcanic rocks associated with silver-gold (Ag-Au) epithermal deposits in the Tonopah, Divide, and Goldfield Mining Districts, Nevada
Miocene calc-alkaline volcanic rocks, part of the southern segment of the ancestral Cascades magmatic arc, are spatially, temporally, and likely genetically associated with precious metal epithermal deposits in the Tonopah, Divide, and Goldfield Districts of west-central Nevada. In the Tonopah mining district, volcanic rocks include the Mizpah...
du Bray, Edward A.; John, David A.; Colgan, Joseph P.; Vikre, Peter G.; Cosca, Michael A.; Morgan, Leah E.Attribution: Geology, Geophysics, and Geochemistry Science Center, Geology, Minerals, Energy, and Geophysics Science Center, Geosciences and Environmental Change Science Center, Mineral Resources Program, Region 7: Upper Colorado Basin
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du Bray, E.A., John, D.A., Colgan, J.P., Vikre, P.G., Cosca, M.A., and Morgan, L.E., 2019, Petrology of volcanic rocks associated with silver-gold (Ag-Au) epithermal deposits in the Tonopah, Divide, and Goldfield mining districts, Nevada: U.S. Geological Survey Scientific Investigations Report 2019–5024, 22 p., https://doi.gov/10.3133/sir20195024.
Year Published: 2019
Petrographic, geochemical, and geochronologic data for cenozoic volcanic rocks of the Tonopah, Divide, and Goldfield Mining Districts, Nevada
The purpose of this report is to summarize geochemical, petrographic, and geochronologic data for samples, principally those of unmineralized Tertiary volcanic rocks, from the Tonopah, Divide, and Goldfield mining districts of west-central Nevada (fig. 1). Much of the data presented here for the Tonopah and Divide districts are for samples...
du Bray, Edward A.; John, David A.; Vikre, Peter G.; Colgan, Joseph P.; Cosca, Michael A.; Morgan, Leah E.; Fleck, Robert J.; Premo, Wayne R.; Holm-Denoma, Christopher S.Attribution: Geology, Geophysics, and Geochemistry Science Center, Geosciences and Environmental Change Science Center, Region 7: Upper Colorado Basin
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du Bray, E.A., John, D.A., Vikre, P.G., Colgan, J.P., Cosca, M.A., Morgan, L.E., Fleck, R.J., Premo, W.R., and Holm-Denoma, C.S., 2019, Petrographic, geochemical, and geochronologic data for Cenozoic volcanic rocks of the Tonopah, Divide, and Goldfield mining districts, Nevada: U.S. Geological Survey Data Series 1099, 15 p., https://doi.org/10.3133/ds1099.
Year Published: 2019
Revisiting Herto: New evidence of Homo sapiens from Ethiopia
Localities in the radiometrically dated Upper Herto Member of Ethiopia’s Bouri Formation continue to produce new data that complement and extend initial reports of fossils and artifacts published in 2003. Results of these revisits are reported here and include the in situ recovery of artifacts from the same sediments containing hominid fossils. We...
Sahle, Yonatan; Beyene, Yonas; Defleur, Alban; Asfaw, Berhane; WoldeGabriel, Giday; Hart, William K; Morgan, Leah E.; Renne, Paul R.; Carlson, Joshua; White, Tim D
Year Published: 2019
A supervolcano and its sidekicks: A 100 ka eruptive chronology of the Fish Canyon Tuff and associated units of the La Garita magmatic system
Establishing temporal constrains on major volcanic eruptions is limited by the precision of existing geochronometers. Prior work on the La Garita caldera, created by the eruption of the Fish Canyon Tuff, failed to resolve temporal differences between pre-, syn-, and post-collapse eruptive units. Here, we report 40Ar/39Ar geochronologic data...
Morgan, Leah E.; Johnstone, Samuel A.; Gilmer, Amy K.; Cosca, Michael A.; Thompson, Ren A.Attribution: Geology, Geophysics, and Geochemistry Science Center, Geosciences and Environmental Change Science Center, Region 7: Upper Colorado Basin
View Citation
Morgan, L. E., Johnstone, S. A., Gilmer, A. K., Cosca, M. A., & Thompson, R. A. (2019). A supervolcano and its sidekicks: A 100 ka eruptive chronology of the Fish Canyon Tuff and associated units of the La Garita magmatic system, Colorado, USA. Geology, 47(5), 453-456.
Pre-USGS Publications
Morgan, L.E., 2017. 40Ar/39Ar and K-Ar Geochronology, in: A.S. Gilbert (ed.), Encyclopedia of Geoarchaeology. Encyclopedia of Earth Science Series. Springer, Dordrecht, https://doi.org/10.1007/978-1-4020-4409-0.
Morgan, L.E., 2015. Noble Gas Mass Spectrometry, in: W.J. Rink, and J.W. Thompson (eds.), Encyclopedia of Scientific Dating Methods. Encyclopedia of Earth Science Series. Springer, Dordrecht, https://doi.org/10.1007/978-94-007-6304-3_118.
Sahle, Y., L.E. Morgan, D.R. Braun, W.K. Hutchings, 2014. Chronological and behavioral contexts of the earliest Middle Stone Age in the Gademotta Formation, Main Ethiopian Rift, Quaternary International, v. 331, p. 6-19, https://doi.org/10.1016/j.quaint.2013.03.010.
Mark, D.F., M. Petraglia, V.C. Smith, L.E. Morgan, D.N. Barfod, B.S Ellis, N.J. Pearce, J.N. Pal, R. Korisettar, 2014. A high-precision 40Ar/39Ar age for the Young Toba Tuff and dating of ultra- distal tephra: forcing of Quaternary climate and implications for hominin occupation of India, Quaternary Geochronology, v. 21, p. 90-103, https://doi.org/10.1016/j.quageo.2012.12.004.
Sahle, Y., W.K. Hutchings, D.R. Braun, J.C. Sealy, L.E. Morgan, A. Negash, B. Atnafu, 2013. Earliest stone-tipped projectiles from the Ethiopian Rift date to >279,000 years ago. PLOS ONE, v. 8, no. 11, e78092, https://doi.org/10.1371/journal.pone.0078092.
Morgan, L.E., D.F. Mark, J. Imlach, D.N. Barfod, 2013. FCs-EK: A new sampling of the Fish Canyon tuff 40Ar/39Ar neutron flux monitor, in: Jourdan, F., Mark, D., and Verati, C. (eds.), Advances in 40Ar/39Ar Dating: from Archaeology to Planetary Sciences. Geological Society, London, Special Publications, 378, https://doi.org/10.1144/SP378.21.
Renne, P.R., A.L. Deino, F.J. Hilgen, K.F. Kuiper, D.F. Mark, W.S. Mitchell, L.E. Morgan, R. Mundil, J. Smit, 2013. Timescales of critical events around the Cretaceous-Paleogene boundary. Science, v. 339, p. 684-687, https://doi.org/10.1126/science.1230492.
Schoene, B., D.J. Condon, L.E. Morgan, N. McLean, 2013. Precision and accuracy in geochronology. Elements Magazine, v.9, no.1, p. 23-28, http://elementsmagazine.org/past-issue-archive/2013-volume-9/#February2013.
Renne, P.R., S.R. Mulcahy, W.S. Cassata,, L.E. Morgan, S.P. Kelley, L. Hlusko, J. Njau, 2012. Retention of inherited Ar by alkali feldspar xenocrysts in a magma: Kinetic constraints from Ba zoning profiles. Geochimica et Cosmochimica Acta, v. 93, p. 129-142, https://doi.org/10.1016/j.gca.2012.06.029.
Morgan, L.E., P.R. Renne, R. Galotti, G. Kieffer, M. Piperno, J.-P. Raynal, 2012. A chronological framework for a long and persistent archeological record: Melka Kunture, Ethiopia. Journal of Human Evolution, v. 62, no. 1, p. 104-115, https://doi.org/10.1016/j.jhevol.2011.10.007.
Frost, S.R., H.L. Schwartz, L. Giemsch, L.E. Morgan, P.R. Renne, M. Wildgoose, C. Saanane, F. Schrenk, K. Harvati, 2012. Refined age estimates and paleoanthropological investigation of the Manyara Beds, Tanzania. Journal of Anthropological Sciences, v. 90, p. 151-161, https://doi.org/10.4436/jass.90001.
Schwartz, H., P.R. Renne, L.E. Morgan, M.M. Wildgoose, P.C. Lippert, S.R. Frost, K. Harvati, F. Schrenk, C. Saanane, 2012. Geochronology of the Manyara Beds, northern Tanzania: stratigraphy and new magnetostratigraphy and 40Ar/39Ar ages. Quaternary Geochronology, v. 7, no. 1, p. 48-66, https://doi.org/10.1016/j.quageo.2011.09.002.
Morgan, L.E., O. Postma, K.F. Kuiper, D.F. Mark, W. van der Plas, S. Davidson, M. Perkin, I. Villa, J.R. Wijbrans, 2011. A metrological approach to measuring 40Ar* concentrations in K-Ar and 40Ar/39Ar mineral standards, Geochem. Geophys. Geosyst., v. 12, p. A0AA20, https://doi.org/10.1029/2011GC003719.
Renne, P.R., A.L. Deino, W.E. Hames, M.T. Heizler, S.R. Hemming, K.V. Hodges, A.A.P. Koppers, D.F. Mark, L.E. Morgan, D. Phillips, B.S. Singer, B.D. Turrin, I.M. Villa, M. Villeneuve and J.R. Wijbrans, 2009. Data reporting norms for 40Ar/39Ar geochronology. Quaternary Geochronology, v. 4, no. 5, p. 346-352, https://doi.org/10.1016/j.quageo.2009.06.005.
Renne, P.R., W.S. Cassata, and L.E. Morgan, 2009. The isotopic composition of atmospheric argon and 40Ar/39Ar geochronology: time for a change? Quaternary Geochronology, v. 4, no. 4, p. 288-298, https://doi.org/10.1016/j.quageo.2009.02.015.
40Ar/39Ar Ages of the Middle Awash Late Miocene
Renne, P. R., L.E. Morgan, G. WoldeGabriel, W.K. Hart, Y. Haile-Selassie, and T.D. White, 2009. 40Ar/39Ar Ages of the Middle Awash Late Miocene, in: Haile-Selassie, Y., and WoldeGabriel, G. (eds.), Ardipithecus kadabba: Late Miocene evidence from the Middle Awash, Ethiopia. University of California Press, Berkeley, CA.
Morgan, L.E., P.R. Renne, R.E. Taylor, and G. WoldeGabriel, 2009. Archaeological age constraints from eruption ages of obsidian: Examples from the Middle Awash, Ethiopia. Quaternary Geochronology, v. 4, p. 193-203, https://doi.org/10.1016/j.quageo.2009.01.001.
Morgan, L.E. and P.R. Renne, 2008. Diachronous Dawn of Africa’s Middle Stone Age: New 40Ar/39Ar ages from the Ethiopian Rift. Geology, v. 36, no. 12, p. 967-970, https://doi.org/10.1130/G25213A.1.
Gihring, T.M., L.-H. Lin, M. Davidson, T.C. Onstott, L. Morgan, M. Milleson, T.L. Kieft, E. Trimarco, D.L. Balkwill, and M.E. Dollhopf, 2006. The Distribution of Microbial Taxa in the Subsurface Water of the Kalahari Shield, South Africa. Geomicrobiology Journal, v. 23, p. 415-430, https://doi.org/10.1080/01490450600875696.