Elmira Wan
Elmira is Project Chief of the Tephrochronology Project at Geology, Minerals, Energy, and Geophysics Science Ctr. She studies tephrochronology & micropaleotonology, specializes in geochronostratigraphy of volcanic ash and planktic foraminiferal biostratigraphy. Afer joining USGS in 1985, her research focuses on marine to terrestrial sites in the Pacific Ocean, mainland U.S., Hawai'i,
Professional Experience
2006 - present, Project Chief, USGS Tephrochronology Project, Menlo Park, CA
1990 - 2006, Geologist, USGS, Tephrochronology Project, Menlo Park, CA
1988 - 1990, Draftsman, Univ. of Utah, Geoscience Illustrations, Salt Lake City, UT
1984 - 1987, Senior Preparator, UC Berkeley Museum of Paleontology, Berkeley, CA
1982 - 1984, Preparator, American Museum of Natural History, New York, NY
1985, 1987, Physical Science Technician, USGS, Branch of Paleontology and Stratigraphy, Menlo Park, CA
Education and Certifications
Paleontology, University of California, Berkeley, 1988
Science and Products
USGS Tephrochronology (Tephra) Project
Tephrochronology is the study of volcanic ash deposits, combining petrology, geochemistry, and isotopic dating methods. We use tephrochronology, along with other chronostratigraphic techniques, to (1) determine the ages of coincident deposits, and, when multiple tephra layers are present, determine the history of geologic events and rates of geologic processes; and (2) correlate sediments from...
Tephra geochemistry of the Ibex Hollow Tuff, a 12-Ma super-eruption
These tables contain geochemical data collected for tephra samples either correlated with or in the same type section with the Ibex Hollow Tuff. Most samples were collected by Andrei Sarna-Wojcicki and Mike Perkins, but some were submitted to the U.S. Geological Survey Tephrochronology Project for analysis by other persons. Electron microprobe analysis (EMA) was performed at the U.S. Geological Su
Geologic map of the Providence Mountains in parts of the Fountain Peak and adjacent 7.5' quadrangles, San Bernardino County, California
IntroductionThe Providence Mountains are in the eastern Mojave Desert about 60 km southeast of Baker, San Bernardino County, California. This range, which is noted for its prominent cliffs of Paleozoic limestone, is part of a northeast-trending belt of mountainous terrain more than 100 km long that also includes the Granite Mountains, Mid Hills, and New York Mountains. Providence Mountains State R
Surficial geology and stratigraphy of Pleistocene Lake Manix, San Bernardino County, California
Pluvial Lake Manix and its surrounding drainage basin, in the central Mojave Desert of California, has been a focus of paleoclimate, surficial processes, and neotectonic studies by the U.S. Geological Survey (USGS) since about 2004. The USGS initiated studies of Lake Manix deposits to improve understanding of the paleoclimatic record and the shifts in atmospheric circulation that controlled precip
Geologic map and upper Paleozoic stratigraphy of the Marble Canyon area, Cottonwood Canyon quadrangle, Death Valley National Park, Inyo County, California
This geologic map and pamphlet focus on the stratigraphy, depositional history, and paleogeographic significance of upper Paleozoic rocks exposed in the Marble Canyon area in Death Valley National Park, California. Bedrock exposed in this area is composed of Mississippian to lower Permian (Cisuralian) marine sedimentary rocks and the Jurassic Hunter Mountain Quartz Monzonite. These units are overl
Filter Total Items: 24
Ibex Hollow Tuff from ca. 12 Ma supereruption, southern Idaho, identified across North America, eastern Pacific Ocean, and Gulf of Mexico
The Ibex Hollow Tuff, 12.08 ± 0.03 Ma (40Ar/39Ar), is a widespread tephra layer erupted from the Bruneau-Jarbidge volcanic field of southern Idaho. Tephra from this eruption was deposited across much of western and central North America and adjacent ocean areas. We identified the Ibex Hollow Tuff at Trapper Creek, Idaho, near its eruption site, and at 15 distal sites, from the Pacific Ocean to the
Authors
Andrei M. Sarna-Wojcicki, Jeffrey R. Knott, John A. Westgate, James R. Budahn, John A. Barron, Colin J. Bray, Greg A. Ludvigson, Charles E. Meyer, David M. Miller, Rick E. Otto, Nicholas J.G. Pearce, Charles C. Smith, Laura Walkup, Elmira Wan, James Yount
Late Cenozoic tephrochronology of the Mount Diablo area within the evolving plate-tectonic boundary zone of northern California
We present a tephrochronologic/chronostratigraphic database for the Mount Diablo area and greater San Francisco Bay region that provides a spatial and temporal framework for geologic studies in the region, including stratigraphy, paleogeography, tectonics, quantification of earth surface processes, recurrence of natural hazards, and climate change. We identified and correlated 34 tephra layers wit
Authors
Andrei Sarna-Wojcicki, Raymond Sullivan, Alan L. Deino, Laura Walkup, J. Ross Wagner, Elmira Wan
Geomorphic history of Lake Manix, Mojave Desert, California: Evolution of a complex terminal lake basin
The US Environmental Protection Agency's short-term freshwater effluent test methods include a fish (Pimephales promelas), a cladoceran (Ceriodaphnia dubia), and a green alga (Raphidocelis subcapitata). There is a recognized need for additional taxa to accompany the three standard species for effluent testing. An appropriate additional taxon is unionid mussels because mussels are widely distribute
Authors
Marith C. Reheis, David M. Miller, James B. Paces, Charles G. Oviatt, Joanna R. Redwine, Darrell Kaufman, Jordon Bright, Elmira Wan
Lake Andrei: A pliocene pluvial lake in Eureka Valley, Eastern California
We used geologic mapping, tephrochronology and 40Ar/39Ar dating to describe evidence of a ca. 3.5 Ma pluvial lake in Eureka Valley, eastern California, that we informally name herein Lake Andrei. We identified six different tuffs in the Eureka Valley drainage basin including two previously undescribed tuffs: the 3.509 ± 0.009 Ma tuff of Hanging Rock Canyon and the 3.506 ± 0.010 Ma tuff of Last Cha
Authors
Jeffrey R. Knott, Elmira Wan, Alan L. Deino, Mitch Casteel, Marith C. Reheis, Fred Phillips, Laura Walkup, Kyle McCarty, David N. Manoukian, Ernest Nuñez
Pleistocene lakes and paleohydrologic environments of the Tecopa basin, California: Constraints on the drainage integration of the Amargosa River
The Tecopa basin in eastern California was a terminal basin that episodically held lakes during most of the Quaternary until the basin and its modern stream, the Amargosa River, became tributary to Death Valley. Although long studied for its sedimentology, diagenesis, and paleomagnetism, the basin’s lacustrine and paleoclimate history has not been well understood, and conflicting interpretations e
Authors
Marith C. Reheis, John Caskey, Jordon Bright, James B. Paces, Shannon A. Mahan, Elmira Wan
Middle Pleistocene infill of Hinkley Valley by Mojave River sediment and associated lake sediment: Depositional architecture and deformation by strike-slip faults
Hinkley Valley in the Mojave Desert, near Barstow about 140 km northeast of Los Angeles and midway between Victorville Valley and the Lake Manix basin, contains a thick sedimentary sequence delivered by the Mojave River. Our study of sediment cores drilled in the valley indicates that Hinkley Valley was probably a closed playa basin with stream inflow from four directions prior to Mojave River inf
Authors
David M. Miller, Elizabeth Haddon, Victoria E. Langenheim, Andrew J. Cyr, Elmira Wan, Laura Walkup, Scott W. Starratt
Late Neogene–Quaternary tephrochronology, stratigraphy, and paleoclimate of Death Valley, California, USA
Sedimentary deposits in midlatitude continental basins often preserve a paleoclimate record complementary to marine-based records. However, deriving that paleoclimate record depends on having well-exposed deposits and establishing a sufficiently robust geochronology. After decades of research, we have been able to correlate 77 tephra beds exposed in multiple stratigraphic sections in the Death Val
Authors
Jeffrey R. Knott, Michael N Machette, Elmira Wan, Ralph E. Klinger, Joseph C Liddicoat, Andrei M. Sarna-Wojcicki, Robert J. Fleck, Alan L. Deino, John W Geissman, Janet L. Slate, David Wahl, Brian P. Wernicke, Stephen G. Wells, John C. Tinsley, Jeffrey C Hathaway, Veva M. Weamer
The story of a Yakima fold and how it informs Late Neogene and Quaternary backarc deformation in the Cascadia subduction zone, Manastash anticline, Washington, USA
The Yakima folds of central Washington, USA, are prominent anticlines that are the primary tectonic features of the backarc of the northern Cascadia subduction zone. What accounts for their topographic expression and how much strain do they accommodate and over what time period? We investigate Manastash anticline, a north vergent fault propagation fold typical of structures in the fold province. F
Authors
Harvey M. Kelsey, Tyler C. Ladinsky, Lydia M. Staisch, Brian Sherrod, Richard J. Blakely, Thomas Pratt, William Stephenson, Jackson K. Odum, Elmira Wan
Holocene environmental changes inferred from biological and sedimentological proxies in a high elevation Great Basin lake in the northern Ruby Mountains, Nevada, USA
Multi-proxy analyses were conducted on a sediment core from Favre Lake, a high elevation cirque lake in the northern Ruby Mountains, Nevada, and provide a ca. 7600 year record of local and regional environmental change. Data indicate that lake levels were lower from 7600-5750 cal yr BP, when local climate was warmer and/or drier than today. Effective moisture increased after 5750 cal yr BP and rem
Authors
David B. Wahl, Scott W. Starratt, Lysanna Anderson, Jennifer E. Kusler, Christopher C. Fuller, Jason A. Addison, Elmira Wan
Quaternary tephrochronology and deposition in the subsurface Sacramento–San Joaquin Delta, California, U.S.A.
We document characteristics of tephra, including facies and geochemistry, from 27 subsurface sites in the Sacramento-San Joaquin Delta, California, to obtain stratigraphic constraints in a complex setting. Analyzed discrete tephra deposits are correlative with: 1) an unnamed tephra from the Carlotta Formation near Ferndale, California, herein informally named the ash of Wildcat Grade (<~1.450 - >~
Authors
Katherine L. Maier, Emma Gatti, Elmira Wan, Daniel J. Ponti, Mark Pagenkopp, Scott W. Starratt, Holly A. Olson, John Tinsley
Distribution of biologic, anthropogenic, and volcanic constituents as a proxy for sediment transport in the San Francisco Bay Coastal System
Although conventional sediment parameters (mean grain size, sorting, and skewness) and provenance have typically been used to infer sediment transport pathways, most freshwater, brackish, and marine environments are also characterized by abundant sediment constituents of biological, and possibly anthropogenic and volcanic, origin that can provide additional insight into local sedimentary processes
Authors
Mary McGann, Li H. Erikson, Elmira Wan, Charles L. Powell, Rosalie F. Maddocks
Structure and tectonic evolution of the eastern Española Basin, Rio Grande rift, north-central New Mexico
We describe the structure of the eastern Española Basin and use stratigraphic and stratal attitude data to interpret its tectonic development. This area consists of a west-dipping half graben in the northern Rio Grande rift that includes several intrabasinal grabens, faults, and folds. The Embudo–Santa Clara–Pajarito fault system, a collection of northeast- and north-striking faults in the center
Authors
Daniel Koning, V. J. Grauch, Sean D. Connell, J. Ferguson, William McIntosh, Janet L. Slate, Elmira Wan, W.S. Baldridge
Science and Products
USGS Tephrochronology (Tephra) Project
Tephrochronology is the study of volcanic ash deposits, combining petrology, geochemistry, and isotopic dating methods. We use tephrochronology, along with other chronostratigraphic techniques, to (1) determine the ages of coincident deposits, and, when multiple tephra layers are present, determine the history of geologic events and rates of geologic processes; and (2) correlate sediments from...
Tephra geochemistry of the Ibex Hollow Tuff, a 12-Ma super-eruption
These tables contain geochemical data collected for tephra samples either correlated with or in the same type section with the Ibex Hollow Tuff. Most samples were collected by Andrei Sarna-Wojcicki and Mike Perkins, but some were submitted to the U.S. Geological Survey Tephrochronology Project for analysis by other persons. Electron microprobe analysis (EMA) was performed at the U.S. Geological Su
Geologic map of the Providence Mountains in parts of the Fountain Peak and adjacent 7.5' quadrangles, San Bernardino County, California
IntroductionThe Providence Mountains are in the eastern Mojave Desert about 60 km southeast of Baker, San Bernardino County, California. This range, which is noted for its prominent cliffs of Paleozoic limestone, is part of a northeast-trending belt of mountainous terrain more than 100 km long that also includes the Granite Mountains, Mid Hills, and New York Mountains. Providence Mountains State R
Surficial geology and stratigraphy of Pleistocene Lake Manix, San Bernardino County, California
Pluvial Lake Manix and its surrounding drainage basin, in the central Mojave Desert of California, has been a focus of paleoclimate, surficial processes, and neotectonic studies by the U.S. Geological Survey (USGS) since about 2004. The USGS initiated studies of Lake Manix deposits to improve understanding of the paleoclimatic record and the shifts in atmospheric circulation that controlled precip
Geologic map and upper Paleozoic stratigraphy of the Marble Canyon area, Cottonwood Canyon quadrangle, Death Valley National Park, Inyo County, California
This geologic map and pamphlet focus on the stratigraphy, depositional history, and paleogeographic significance of upper Paleozoic rocks exposed in the Marble Canyon area in Death Valley National Park, California. Bedrock exposed in this area is composed of Mississippian to lower Permian (Cisuralian) marine sedimentary rocks and the Jurassic Hunter Mountain Quartz Monzonite. These units are overl
Filter Total Items: 24
Ibex Hollow Tuff from ca. 12 Ma supereruption, southern Idaho, identified across North America, eastern Pacific Ocean, and Gulf of Mexico
The Ibex Hollow Tuff, 12.08 ± 0.03 Ma (40Ar/39Ar), is a widespread tephra layer erupted from the Bruneau-Jarbidge volcanic field of southern Idaho. Tephra from this eruption was deposited across much of western and central North America and adjacent ocean areas. We identified the Ibex Hollow Tuff at Trapper Creek, Idaho, near its eruption site, and at 15 distal sites, from the Pacific Ocean to the
Authors
Andrei M. Sarna-Wojcicki, Jeffrey R. Knott, John A. Westgate, James R. Budahn, John A. Barron, Colin J. Bray, Greg A. Ludvigson, Charles E. Meyer, David M. Miller, Rick E. Otto, Nicholas J.G. Pearce, Charles C. Smith, Laura Walkup, Elmira Wan, James Yount
Late Cenozoic tephrochronology of the Mount Diablo area within the evolving plate-tectonic boundary zone of northern California
We present a tephrochronologic/chronostratigraphic database for the Mount Diablo area and greater San Francisco Bay region that provides a spatial and temporal framework for geologic studies in the region, including stratigraphy, paleogeography, tectonics, quantification of earth surface processes, recurrence of natural hazards, and climate change. We identified and correlated 34 tephra layers wit
Authors
Andrei Sarna-Wojcicki, Raymond Sullivan, Alan L. Deino, Laura Walkup, J. Ross Wagner, Elmira Wan
Geomorphic history of Lake Manix, Mojave Desert, California: Evolution of a complex terminal lake basin
The US Environmental Protection Agency's short-term freshwater effluent test methods include a fish (Pimephales promelas), a cladoceran (Ceriodaphnia dubia), and a green alga (Raphidocelis subcapitata). There is a recognized need for additional taxa to accompany the three standard species for effluent testing. An appropriate additional taxon is unionid mussels because mussels are widely distribute
Authors
Marith C. Reheis, David M. Miller, James B. Paces, Charles G. Oviatt, Joanna R. Redwine, Darrell Kaufman, Jordon Bright, Elmira Wan
Lake Andrei: A pliocene pluvial lake in Eureka Valley, Eastern California
We used geologic mapping, tephrochronology and 40Ar/39Ar dating to describe evidence of a ca. 3.5 Ma pluvial lake in Eureka Valley, eastern California, that we informally name herein Lake Andrei. We identified six different tuffs in the Eureka Valley drainage basin including two previously undescribed tuffs: the 3.509 ± 0.009 Ma tuff of Hanging Rock Canyon and the 3.506 ± 0.010 Ma tuff of Last Cha
Authors
Jeffrey R. Knott, Elmira Wan, Alan L. Deino, Mitch Casteel, Marith C. Reheis, Fred Phillips, Laura Walkup, Kyle McCarty, David N. Manoukian, Ernest Nuñez
Pleistocene lakes and paleohydrologic environments of the Tecopa basin, California: Constraints on the drainage integration of the Amargosa River
The Tecopa basin in eastern California was a terminal basin that episodically held lakes during most of the Quaternary until the basin and its modern stream, the Amargosa River, became tributary to Death Valley. Although long studied for its sedimentology, diagenesis, and paleomagnetism, the basin’s lacustrine and paleoclimate history has not been well understood, and conflicting interpretations e
Authors
Marith C. Reheis, John Caskey, Jordon Bright, James B. Paces, Shannon A. Mahan, Elmira Wan
Middle Pleistocene infill of Hinkley Valley by Mojave River sediment and associated lake sediment: Depositional architecture and deformation by strike-slip faults
Hinkley Valley in the Mojave Desert, near Barstow about 140 km northeast of Los Angeles and midway between Victorville Valley and the Lake Manix basin, contains a thick sedimentary sequence delivered by the Mojave River. Our study of sediment cores drilled in the valley indicates that Hinkley Valley was probably a closed playa basin with stream inflow from four directions prior to Mojave River inf
Authors
David M. Miller, Elizabeth Haddon, Victoria E. Langenheim, Andrew J. Cyr, Elmira Wan, Laura Walkup, Scott W. Starratt
Late Neogene–Quaternary tephrochronology, stratigraphy, and paleoclimate of Death Valley, California, USA
Sedimentary deposits in midlatitude continental basins often preserve a paleoclimate record complementary to marine-based records. However, deriving that paleoclimate record depends on having well-exposed deposits and establishing a sufficiently robust geochronology. After decades of research, we have been able to correlate 77 tephra beds exposed in multiple stratigraphic sections in the Death Val
Authors
Jeffrey R. Knott, Michael N Machette, Elmira Wan, Ralph E. Klinger, Joseph C Liddicoat, Andrei M. Sarna-Wojcicki, Robert J. Fleck, Alan L. Deino, John W Geissman, Janet L. Slate, David Wahl, Brian P. Wernicke, Stephen G. Wells, John C. Tinsley, Jeffrey C Hathaway, Veva M. Weamer
The story of a Yakima fold and how it informs Late Neogene and Quaternary backarc deformation in the Cascadia subduction zone, Manastash anticline, Washington, USA
The Yakima folds of central Washington, USA, are prominent anticlines that are the primary tectonic features of the backarc of the northern Cascadia subduction zone. What accounts for their topographic expression and how much strain do they accommodate and over what time period? We investigate Manastash anticline, a north vergent fault propagation fold typical of structures in the fold province. F
Authors
Harvey M. Kelsey, Tyler C. Ladinsky, Lydia M. Staisch, Brian Sherrod, Richard J. Blakely, Thomas Pratt, William Stephenson, Jackson K. Odum, Elmira Wan
Holocene environmental changes inferred from biological and sedimentological proxies in a high elevation Great Basin lake in the northern Ruby Mountains, Nevada, USA
Multi-proxy analyses were conducted on a sediment core from Favre Lake, a high elevation cirque lake in the northern Ruby Mountains, Nevada, and provide a ca. 7600 year record of local and regional environmental change. Data indicate that lake levels were lower from 7600-5750 cal yr BP, when local climate was warmer and/or drier than today. Effective moisture increased after 5750 cal yr BP and rem
Authors
David B. Wahl, Scott W. Starratt, Lysanna Anderson, Jennifer E. Kusler, Christopher C. Fuller, Jason A. Addison, Elmira Wan
Quaternary tephrochronology and deposition in the subsurface Sacramento–San Joaquin Delta, California, U.S.A.
We document characteristics of tephra, including facies and geochemistry, from 27 subsurface sites in the Sacramento-San Joaquin Delta, California, to obtain stratigraphic constraints in a complex setting. Analyzed discrete tephra deposits are correlative with: 1) an unnamed tephra from the Carlotta Formation near Ferndale, California, herein informally named the ash of Wildcat Grade (<~1.450 - >~
Authors
Katherine L. Maier, Emma Gatti, Elmira Wan, Daniel J. Ponti, Mark Pagenkopp, Scott W. Starratt, Holly A. Olson, John Tinsley
Distribution of biologic, anthropogenic, and volcanic constituents as a proxy for sediment transport in the San Francisco Bay Coastal System
Although conventional sediment parameters (mean grain size, sorting, and skewness) and provenance have typically been used to infer sediment transport pathways, most freshwater, brackish, and marine environments are also characterized by abundant sediment constituents of biological, and possibly anthropogenic and volcanic, origin that can provide additional insight into local sedimentary processes
Authors
Mary McGann, Li H. Erikson, Elmira Wan, Charles L. Powell, Rosalie F. Maddocks
Structure and tectonic evolution of the eastern Española Basin, Rio Grande rift, north-central New Mexico
We describe the structure of the eastern Española Basin and use stratigraphic and stratal attitude data to interpret its tectonic development. This area consists of a west-dipping half graben in the northern Rio Grande rift that includes several intrabasinal grabens, faults, and folds. The Embudo–Santa Clara–Pajarito fault system, a collection of northeast- and north-striking faults in the center
Authors
Daniel Koning, V. J. Grauch, Sean D. Connell, J. Ferguson, William McIntosh, Janet L. Slate, Elmira Wan, W.S. Baldridge