R. Randall Schumann
I am a Geologist Emeritus in the Geosciences and Environmental Change Science Center in Denver, Colorado, conducting studies on the effects of climate change on landscape dynamics in coastal and fluvial environments.
I began my career at the USGS in 1980 with research focusing on fluvial geomorphology and sedimentology of anastomosing river channels; wetland hydrology; surficial uranium deposits; and the geology and geochemistry of radon in rocks and soils. I received the Department of Interior's Superior Service Award for my work on radon. I was a member of the Central Publications Group from 1995-1997 and was coordinator of computer support, GIS, and web services for the Earth Surface Processes Team from 1997-2000. I served as Team Chief Scientist (Center Director) of the Earth Surface Processes Team from 2002-2008, director of the National Ice Core Laboratory from 2007-2008, and Center Director of GECSC 2018-2020. I retired from USGS in 2022 but I am pleased and honored to continue pursuing my research interests as a Scientist Emeritus.
Education and Certifications
M.S., Geology, Colorado State University, 1985
B.A., Geography, University of Colorado, 1979
Science and Products
Filter Total Items: 39
A tale of two islands: Tectonic and orbital controls on marine terrace reoccupation, Channel Islands National Park, California, USA
In areas of low uplift rate on the Pacific Coast of North America, reoccupation of emergent marine terraces by later high sea-stands has been hypothesised to explain the existence of thermally anomalous fauna (mixtures of warm and cool species) of last interglacial age. If uplift rates have been low for much of the Quaternary, it follows that higher (older) terraces should also show evidence of re
Authors
Daniel R. Muhs, Lindsey T. Groves, Kathleen R. Simmons, R. Randall Schumann, Stephen B. DeVogel
Plant macrofossil data for 48-0 ka in the USGS North American Packrat Midden Database, version 5.0
Plant macrofossils from packrat (Neotoma spp.) middens provide direct evidence of past vegetation changes in arid regions of North America. Here we describe the newest version (version 5.0) of the U.S. Geological Survey (USGS) North American Packrat Midden Database. The database contains published and contributed data from 3,331 midden samples collected in southwest Canada, the western United Stat
Authors
Laura E. Strickland, Robert S. Thompson, Sarah Shafer, Patrick J. Bartlein, Richard T. Pelltier, Katherine H Anderson, R. Randall Schumann, Andrew K. McFadden
A complex record of last interglacial sea-level history and paleozoogeography, Santa Rosa Island, Channel Islands National Park, California, USA
Studies of marine terraces and their fossils can yield important information about sea level history, tectonic uplift rates, and paleozoogeography, but some aspects of terrace history, particularly with regard to their fossil record, are not clearly understood. Marine terraces are well preserved on Santa Rosa Island, California, and the island is situated near a major marine faunal boundary. Two p
Authors
Daniel R. Muhs, Lindsey T. Groves, Kathleen R. Simmons, R. Randall Schumann, Scott A. Minor
The marine terraces of Santa Cruz Island, California: Implications for glacial isostatic adjustment models of last-interglacial sea-level history
Glacial isostatic adjustment (GIA) models hypothesize that along coastal California, last interglacial (LIG, broadly from ~130 to ~115 ka) sea level could have been as high as +11 m to +13 m, relative to present, substantially higher than the commonly estimated elevation of +6 m. Areas with low uplift rates can test whether such models are valid. Marine terraces on Santa Cruz Island have previousl
Authors
Daniel R. Muhs, R. Randall Schumann, Lindsey T. Groves, Kathleen R. Simmons, Christopher R. Florian
Testing glacial isostatic adjustment models of last-interglacial sea level history in the Bahamas and Bermuda
Part of the spatial variation in the apparent sea-level record of the last interglacial (LIG) period is due to the diverse response of coastlines to glacial isostatic adjustment (GIA) processes, particularly where coastlines were close to the Laurentide Ice Sheet during the past two glacial periods. We tested modeled LIG paleo-sea levels on New Providence Island (NPI), Bahamas and Bermuda by inves
Authors
Daniel R. Muhs, Kathleen R. Simmons, R. Randall Schumann, Eugene S. Schweig, Mark P. Rowe
Fluvial sedimentary history of Arlington Canyon, Channel Islands National Park, California
Arlington Canyon, in the northwest part of Santa Rosa Island, Channel Islands National Park, California, has been the setting for important scientific discoveries over the past half century, including the oldest human remains in North America, several vertebrate fossil sites, and purported evidence of a catastrophic extinction event at the end of the Pleistocene. The canyon is filled with alluvial
Authors
R. Randall Schumann, Jeffrey S. Pigati
Quaternary sea-level history and the origin of the northernmost coastal aeolianites in the Americas: Channel Islands National Park, California, USA
Along most of the Pacific Coast of North America, sand dunes are dominantly silicate-rich. On the California Channel Islands, however, dunes are carbonate-rich, due to high productivity offshore and a lack of dilution by silicate minerals. Older sands on the Channel Islands contain enough carbonate to be cemented into aeolianite. Several generations of carbonate aeolianites are present on the Cali
Authors
Daniel R. Muhs, Jeffrey S. Pigati, R. Randall Schumann, Gary L. Skipp, Naomi Porat, Stephen B. DeVogel
Reply to the discussion of Pinter et al. on ‘Fluvial system response to late Pleistocene-Holocene sea-level change on Santa Rosa Island, Channel Islands National Park, California’ by Schumann et al. (2016)
We appreciate the thoughtful discussion offered by Pinter et al. (2017) because it gives us an opportunity to elucidate some of the main points of our study, address some apparent misinterpretations, and recapitulate one of our conclusions. Pinter et al.’s discussion emphasizes and reinforces some of the important concepts we presented but also raises questions regarding specific aspects of our st
Authors
R. Randall Schumann, Jeffrey S. Pigati
Late Quaternary fluvial history of Santa Cruz Island, California, USA
The geologic history of fluvial systems on Santa Cruz Island (SCI) is complex, involving responses to both allogenic and autogenic forcings. During periods of low or lowering sea level, canyons on the island were eroded and sediment was transported off the island onto the exposed marine shelf. When sea level rose, streams aggraded, building a sedimentary wedge that progressed from the shelf upstre
Authors
R. Randall Schumann, Jeffrey S. Pigati
Uranium delivery and uptake in a montane wetland, north-central Colorado, USA
Comprehensive sampling of peat, underlying lakebed sediments, and coexisting waters of a naturally uraniferous montane wetland are combined with hydrologic measurements to define the important controls on uranium (U) supply and uptake. The major source of U to the wetland is groundwater flowing through locally fractured and faulted granite gneiss of Proterozoic age. Dissolved U concentrations in f
Authors
R. Randall Schumann, Robert A. Zielinski, James K. Otton, Michael P. Pantea, William H. Orem
Fluvial system response to late Pleistocene-Holocene sea-level change on Santa Rosa Island, Channel Islands National Park, California
Santa Rosa Island (SRI) is one of four east-west aligned islands forming the northern Channel Islands chain, and one of the five islands in Channel Islands National Park, California, USA. The island setting provides an unparalleled environment in which to record the response of fluvial systems to major changes of sea level. Many of the larger streams on the island occupy broad valleys that have be
Authors
R. Randall Schumann, Jeffery S. Pigati, John P. McGeehin
Late Quaternary sea-level history and the antiquity of mammoths (Mammuthus exilis and Mammuthus columbi), Channel Islands NationalPark, California, USA
Fossils of Columbian mammoths (Mammuthus columbi) and pygmy mammoths (Mammuthus exilis) have been reported from Channel Islands National Park, California. Most date to the last glacial period (Marine Isotope Stage [MIS] 2), but a tusk of M. exilis (or immature M. columbi) was found in the lowest marine terrace of Santa Rosa Island. Uranium-series dating of corals yielded ages from 83.8 ± 0.6 ka to
Authors
Daniel R. Muhs, Kathleen R. Simmons, Lindsey T. Groves, John P. McGeehin, R. Randall Schumann, Larry D. Agenbroad
Geologic Records of High Sea Levels
This project studies past high sea levels on coastlines that preserve fossil coral reefs or marine terraces. We ascertain the magnitudes of sea-level high stands by field mapping, stratigraphic measurements, and precise elevation measurements. Geochronology is accomplished by radiocarbon dating of mollusks (for Holocene-to-last-glacial deposits), uranium-series dating of corals (for high-sea...
Strontium isotope, amino acid, and fossil taxonomy data to aid in identifying instances of marine terrace reoccupation on Anacapa and San Miguel Islands, California, USA
In areas of low uplift rate on the Pacific Coast of North America, reoccupation of emergent marine terraces by later high-sea stands has been hypothesized to explain the existence of thermally anomalous faunas (mixtures of warm and cool species) of last interglacial age. If uplift rates have been low for much of the Quaternary, it follows that higher (older) terraces should also show evidence of r
Uranium and Strontium geochronology data for marine terraces on Santa Rosa Island, Channel Islands National Park, California, USA
Studies of marine terraces and their fossils can yield important information about sea level history, tectonic uplift rates, and paleozoogeography. The marine terrace record on Santa Rosa Island, California is complex. Two prominent low-elevation terraces appear to record the ~80 ka (MIS 5a) and ~120 ka (MIS 5e) high-sea stands, based on U-series dating of fossil corals, but interpretations are te
USGS North American Packrat Midden Database, Version 5.0
This data release contains the data tables for the USGS North American Packrat Midden Database (version 5.0). This version of the Midden Database contains data for 3,331 packrat midden samples obtained from published sources (journal articles, book chapters, theses, dissertations, government and private industry reports, conference proceedings) as well as unpublished data contributed by researche
Stratigraphic, geochemical, and hydrologic data for the Boston Peak wetland, Larimer County, CO, USA
Comprehensive sampling of peat, underlying lakebed sediments, and coexisting waters of a naturally uraniferous montane wetland are combined with hydrologic measurements to define the important controls on uranium (U) supply and uptake. The major source of U to the wetland is groundwater flowing through locally fractured and faulted granite gneiss of Proterozoic age. Dissolved U concentrations in f
Map showing radon potential of rocks and soils in Fairfax County, Virginia
Since 1984, indoor radon has gained national attention as a significant health hazard in the United States. Radon is a colorless, odorless, radioactive gas derived from uranium by radioactive decay. The U.S. Environmental Protection Agency (EPA) now projects that 5,000 to 20,000 lung-cancer deaths per year may be attributed to the long-term exposure to indoor radon and its radioactive decay produc
Science and Products
Filter Total Items: 39
A tale of two islands: Tectonic and orbital controls on marine terrace reoccupation, Channel Islands National Park, California, USA
In areas of low uplift rate on the Pacific Coast of North America, reoccupation of emergent marine terraces by later high sea-stands has been hypothesised to explain the existence of thermally anomalous fauna (mixtures of warm and cool species) of last interglacial age. If uplift rates have been low for much of the Quaternary, it follows that higher (older) terraces should also show evidence of re
Authors
Daniel R. Muhs, Lindsey T. Groves, Kathleen R. Simmons, R. Randall Schumann, Stephen B. DeVogel
Plant macrofossil data for 48-0 ka in the USGS North American Packrat Midden Database, version 5.0
Plant macrofossils from packrat (Neotoma spp.) middens provide direct evidence of past vegetation changes in arid regions of North America. Here we describe the newest version (version 5.0) of the U.S. Geological Survey (USGS) North American Packrat Midden Database. The database contains published and contributed data from 3,331 midden samples collected in southwest Canada, the western United Stat
Authors
Laura E. Strickland, Robert S. Thompson, Sarah Shafer, Patrick J. Bartlein, Richard T. Pelltier, Katherine H Anderson, R. Randall Schumann, Andrew K. McFadden
A complex record of last interglacial sea-level history and paleozoogeography, Santa Rosa Island, Channel Islands National Park, California, USA
Studies of marine terraces and their fossils can yield important information about sea level history, tectonic uplift rates, and paleozoogeography, but some aspects of terrace history, particularly with regard to their fossil record, are not clearly understood. Marine terraces are well preserved on Santa Rosa Island, California, and the island is situated near a major marine faunal boundary. Two p
Authors
Daniel R. Muhs, Lindsey T. Groves, Kathleen R. Simmons, R. Randall Schumann, Scott A. Minor
The marine terraces of Santa Cruz Island, California: Implications for glacial isostatic adjustment models of last-interglacial sea-level history
Glacial isostatic adjustment (GIA) models hypothesize that along coastal California, last interglacial (LIG, broadly from ~130 to ~115 ka) sea level could have been as high as +11 m to +13 m, relative to present, substantially higher than the commonly estimated elevation of +6 m. Areas with low uplift rates can test whether such models are valid. Marine terraces on Santa Cruz Island have previousl
Authors
Daniel R. Muhs, R. Randall Schumann, Lindsey T. Groves, Kathleen R. Simmons, Christopher R. Florian
Testing glacial isostatic adjustment models of last-interglacial sea level history in the Bahamas and Bermuda
Part of the spatial variation in the apparent sea-level record of the last interglacial (LIG) period is due to the diverse response of coastlines to glacial isostatic adjustment (GIA) processes, particularly where coastlines were close to the Laurentide Ice Sheet during the past two glacial periods. We tested modeled LIG paleo-sea levels on New Providence Island (NPI), Bahamas and Bermuda by inves
Authors
Daniel R. Muhs, Kathleen R. Simmons, R. Randall Schumann, Eugene S. Schweig, Mark P. Rowe
Fluvial sedimentary history of Arlington Canyon, Channel Islands National Park, California
Arlington Canyon, in the northwest part of Santa Rosa Island, Channel Islands National Park, California, has been the setting for important scientific discoveries over the past half century, including the oldest human remains in North America, several vertebrate fossil sites, and purported evidence of a catastrophic extinction event at the end of the Pleistocene. The canyon is filled with alluvial
Authors
R. Randall Schumann, Jeffrey S. Pigati
Quaternary sea-level history and the origin of the northernmost coastal aeolianites in the Americas: Channel Islands National Park, California, USA
Along most of the Pacific Coast of North America, sand dunes are dominantly silicate-rich. On the California Channel Islands, however, dunes are carbonate-rich, due to high productivity offshore and a lack of dilution by silicate minerals. Older sands on the Channel Islands contain enough carbonate to be cemented into aeolianite. Several generations of carbonate aeolianites are present on the Cali
Authors
Daniel R. Muhs, Jeffrey S. Pigati, R. Randall Schumann, Gary L. Skipp, Naomi Porat, Stephen B. DeVogel
Reply to the discussion of Pinter et al. on ‘Fluvial system response to late Pleistocene-Holocene sea-level change on Santa Rosa Island, Channel Islands National Park, California’ by Schumann et al. (2016)
We appreciate the thoughtful discussion offered by Pinter et al. (2017) because it gives us an opportunity to elucidate some of the main points of our study, address some apparent misinterpretations, and recapitulate one of our conclusions. Pinter et al.’s discussion emphasizes and reinforces some of the important concepts we presented but also raises questions regarding specific aspects of our st
Authors
R. Randall Schumann, Jeffrey S. Pigati
Late Quaternary fluvial history of Santa Cruz Island, California, USA
The geologic history of fluvial systems on Santa Cruz Island (SCI) is complex, involving responses to both allogenic and autogenic forcings. During periods of low or lowering sea level, canyons on the island were eroded and sediment was transported off the island onto the exposed marine shelf. When sea level rose, streams aggraded, building a sedimentary wedge that progressed from the shelf upstre
Authors
R. Randall Schumann, Jeffrey S. Pigati
Uranium delivery and uptake in a montane wetland, north-central Colorado, USA
Comprehensive sampling of peat, underlying lakebed sediments, and coexisting waters of a naturally uraniferous montane wetland are combined with hydrologic measurements to define the important controls on uranium (U) supply and uptake. The major source of U to the wetland is groundwater flowing through locally fractured and faulted granite gneiss of Proterozoic age. Dissolved U concentrations in f
Authors
R. Randall Schumann, Robert A. Zielinski, James K. Otton, Michael P. Pantea, William H. Orem
Fluvial system response to late Pleistocene-Holocene sea-level change on Santa Rosa Island, Channel Islands National Park, California
Santa Rosa Island (SRI) is one of four east-west aligned islands forming the northern Channel Islands chain, and one of the five islands in Channel Islands National Park, California, USA. The island setting provides an unparalleled environment in which to record the response of fluvial systems to major changes of sea level. Many of the larger streams on the island occupy broad valleys that have be
Authors
R. Randall Schumann, Jeffery S. Pigati, John P. McGeehin
Late Quaternary sea-level history and the antiquity of mammoths (Mammuthus exilis and Mammuthus columbi), Channel Islands NationalPark, California, USA
Fossils of Columbian mammoths (Mammuthus columbi) and pygmy mammoths (Mammuthus exilis) have been reported from Channel Islands National Park, California. Most date to the last glacial period (Marine Isotope Stage [MIS] 2), but a tusk of M. exilis (or immature M. columbi) was found in the lowest marine terrace of Santa Rosa Island. Uranium-series dating of corals yielded ages from 83.8 ± 0.6 ka to
Authors
Daniel R. Muhs, Kathleen R. Simmons, Lindsey T. Groves, John P. McGeehin, R. Randall Schumann, Larry D. Agenbroad
Geologic Records of High Sea Levels
This project studies past high sea levels on coastlines that preserve fossil coral reefs or marine terraces. We ascertain the magnitudes of sea-level high stands by field mapping, stratigraphic measurements, and precise elevation measurements. Geochronology is accomplished by radiocarbon dating of mollusks (for Holocene-to-last-glacial deposits), uranium-series dating of corals (for high-sea...
Strontium isotope, amino acid, and fossil taxonomy data to aid in identifying instances of marine terrace reoccupation on Anacapa and San Miguel Islands, California, USA
In areas of low uplift rate on the Pacific Coast of North America, reoccupation of emergent marine terraces by later high-sea stands has been hypothesized to explain the existence of thermally anomalous faunas (mixtures of warm and cool species) of last interglacial age. If uplift rates have been low for much of the Quaternary, it follows that higher (older) terraces should also show evidence of r
Uranium and Strontium geochronology data for marine terraces on Santa Rosa Island, Channel Islands National Park, California, USA
Studies of marine terraces and their fossils can yield important information about sea level history, tectonic uplift rates, and paleozoogeography. The marine terrace record on Santa Rosa Island, California is complex. Two prominent low-elevation terraces appear to record the ~80 ka (MIS 5a) and ~120 ka (MIS 5e) high-sea stands, based on U-series dating of fossil corals, but interpretations are te
USGS North American Packrat Midden Database, Version 5.0
This data release contains the data tables for the USGS North American Packrat Midden Database (version 5.0). This version of the Midden Database contains data for 3,331 packrat midden samples obtained from published sources (journal articles, book chapters, theses, dissertations, government and private industry reports, conference proceedings) as well as unpublished data contributed by researche
Stratigraphic, geochemical, and hydrologic data for the Boston Peak wetland, Larimer County, CO, USA
Comprehensive sampling of peat, underlying lakebed sediments, and coexisting waters of a naturally uraniferous montane wetland are combined with hydrologic measurements to define the important controls on uranium (U) supply and uptake. The major source of U to the wetland is groundwater flowing through locally fractured and faulted granite gneiss of Proterozoic age. Dissolved U concentrations in f
Map showing radon potential of rocks and soils in Fairfax County, Virginia
Since 1984, indoor radon has gained national attention as a significant health hazard in the United States. Radon is a colorless, odorless, radioactive gas derived from uranium by radioactive decay. The U.S. Environmental Protection Agency (EPA) now projects that 5,000 to 20,000 lung-cancer deaths per year may be attributed to the long-term exposure to indoor radon and its radioactive decay produc