I am a geochemist and geologist specializing in lakes, wetlands, and soils, with a focus on carbonates.
I am particularly interested in what isotopes in carbonates can say about the geologic history of these types of environments. My main research goal is to understand what affects water availability in arid regions. I have done research in Tibet, the Andes, and the western United States. My current research is focused in the US Great Basin, Alaska, and the southern Rocky Mountains.
Science and Products
Denali National Park Geohazards Geologic Mapping
Geologic Framework of the Intermountain West
Serving the U.S. Geological Survey’s geochronological data
Paleohydrology of Desert Wetlands
USGS Geochron: A Database of Geochronological and Thermochronological Dates and Data
Data Release for Reconstructing paleohydrology in the northwest Great Basin since the last deglaciation using Paisley Caves fish remains (Oregon, U.S.A.)
Data release for Middle Pleistocene formation of the Rio Grande Gorge, San Luis Valley, south-central Colorado and north-central New Mexico, USA: Process, timing, and downstream implications
Data Rease for "Isotopic constraints on middle Pleistocene cave evolution, paleohydrologic flow, and environmental conditions from Fitton Cave speleothems, Buffalo National River, Arkansas"
The Seamless Integrated Geologic Mapping (SIGMa) extension to the Geologic Map Schema (GeMS)
Central Andean (28–34°S) flood record 0–25 ka from Salinas del Bebedero, Argentina
Evidence for humans in North America during the Last Glacial Maximum
Reconstructing paleohydrology in the northwest Great Basin since the last deglaciation using Paisley Caves fish remains (Oregon, U.S.A.)
Assessing geohazards to the Denali National Park road with geologic mapping
Middle Pleistocene formation of the Rio Grande Gorge, San Luis Valley, south-central Colorado and north-central New Mexico, USA: Process, timing, and downstream implications
North-south dipole in winter hydroclimate in the western United States during the last deglaciation
Establishing chronologies for alluvial-fan sequences with analysis of high-resolution topographic data: San Luis Valley, Colorado, USA
Isotopic characterization of late Neogene travertine deposits at Barrancas Blancas in the eastern Atacama Desert, Chile
Stable C, O and clumped isotope systematics and 14C geochronology of carbonates from the Quaternary Chewaucan closed-basin lake system, Great Basin, USA: Implications for paleoenvironmental reconstructions using carbonates
Preliminary geologic map of the Big Costilla Peak area, Taos County, New Mexico, and Costilla County, Colorado
Preliminary geologic map of the Vermejo Peak area, Colfax and Taos Counties, New Mexico and Las Animas and Costilla Counties, Colorado
Non-USGS Publications**
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
- Science
Denali National Park Geohazards Geologic Mapping
Denali National Park (DENA) is a major draw for tourism and recreation and a major economic engine for central Alaska. However, the geologic forces that created the steep landscape of DENA also make it prone to geologic hazards (geohazards) like landslides, debris flows, and earthquakes. DENA has only one major road, called the ‘Park Road’, that serves nearly all of its infrastructure. Since 2017...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...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 projPaleohydrology of Desert Wetlands
Springs and wetlands are among the most highly threatened ecosystems on Earth. Although geographically limited, they support more than 20% of all the threatened and endangered species in the United States. Scientists from the U.S. Geological Survey are examining the rock record to determine how springs and wetlands responded to abrupt climate change during prehistoric times and the recent geologic... - Data
USGS Geochron: A Database of Geochronological and Thermochronological Dates and Data
USGS Geochron is a database of geochronological and thermochronological dates and data. The data set contains published ages, dates, analytical information, sample metadata including location, and source citations. The following analytical techniques are represented in the data set: 40Ar/39Ar, K-Ar, U-Th-Pb, Sm-Nd, Rb-Sr, Lu-Hf, fission track, and luminescence. This data set incorporates data prevData Release for Reconstructing paleohydrology in the northwest Great Basin since the last deglaciation using Paisley Caves fish remains (Oregon, U.S.A.)
This dataset includes tables of stratigraphic age-depth information for Paisley Caves 2 and 5, in Oregon U.S.A., along with tables of fish bone abundance and stable and strontium isotopic data for fish remains and geological samples from the study area surrounding the Paisley Caves.Data release for Middle Pleistocene formation of the Rio Grande Gorge, San Luis Valley, south-central Colorado and north-central New Mexico, USA: Process, timing, and downstream implications
This dataset includes tables of 3He-isotopic data used to calculate surface exposure ages for samples of basalt, and U- and Th-isotopic data used to calculate uranium-series age estimates (230Th/U method) and initial 234U/238U activity ratios for samples of pedogenic carbonate formed in soils on alluvial fans in the San Luis Valley, Colorado, USA. These data are included in the publication: RuleData Rease for "Isotopic constraints on middle Pleistocene cave evolution, paleohydrologic flow, and environmental conditions from Fitton Cave speleothems, Buffalo National River, Arkansas"
Data release for "Isotopic constraints on middle Pleistocene cave evolution, paleohydrologic flow, and environmental conditions from Fitton Cave speleothems, Buffalo National River, Arkansas". Extended abstract for the 2017 Karst Interest Group meeting. Includes sample information, U-Th isotope compositions, calculated U-series (230Th/U) ages and initial 234U/238U activity ratios, Sr isotopic co - Publications
The Seamless Integrated Geologic Mapping (SIGMa) extension to the Geologic Map Schema (GeMS)
Geologic maps are the fundamental building blocks of surface and subsurface three-dimensional geologic framework models of the Earth’s crust. However, as the production and availability of geologic map databases continues to increase, inconsistent data models and the lack of synthesized, national geologic map data at scales appropriate for informed decision making negatively affect the functionalCentral Andean (28–34°S) flood record 0–25 ka from Salinas del Bebedero, Argentina
The Salinas del Bebedero occupies an isolated basin in the foreland of central Argentina at 33°S and was flooded repeatedly over past 25 ka. Isotopic evidence demonstrates that this flooding was due to overflow of the nearby Río Desaguadero with waters derived from the distant (≥300 km) central Andes between 28–34°S. Stratigraphic and shoreline evidence shows that floods occurred most frequently bEvidence for humans in North America during the Last Glacial Maximum
Archaeologists and researchers in allied fields have long sought to understand human colonization of North America. When, how, and from where did people migrate, and what were the consequences of their arrival for the established fauna and landscape are enduring questions. Here, we present evidence from excavated surfaces of in situ human footprints from White Sands National Park (New Mexico, USA)Reconstructing paleohydrology in the northwest Great Basin since the last deglaciation using Paisley Caves fish remains (Oregon, U.S.A.)
The arid northwest Great Basin underwent substantial hydroclimate changes in the past 15,000 years, greatly affecting its desert ecosystems and prehistoric people. There are conflicting interpretations of the timing of hydrologic changes in this region, requiring more records to resolve the dominant climatic drivers. The Paisley Caves archaeological site, located near former pluvial Lake ChewaucanAssessing geohazards to the Denali National Park road with geologic mapping
Denali National Park (DENA) is home to iconic and breathtaking landscapes surrounding the tallest mountain range in North America, the Alaska Range. The park, which covers 6 million acres, is a major draw for tourism and recreation, making it an important economic engine for central Alaska. However, the geologic forces that created the beautiful, steep landscape of DENA also make it prone to geoloMiddle Pleistocene formation of the Rio Grande Gorge, San Luis Valley, south-central Colorado and north-central New Mexico, USA: Process, timing, and downstream implications
The Rio Grande is the fourth longest river in North America extending over 3,000 km from the Rocky Mountains to the Gulf of Mexico. The Pleistocene evolution of this river from individual subbasins into a coalesced fluvial system has been long debated. Herein, we constrain the middle Pleistocene evolution of the northernmost and largest Rio Grande basin, the San Luis basin, and the timing of incisNorth-south dipole in winter hydroclimate in the western United States during the last deglaciation
During the termination of the last glacial period the western U.S. experienced exceptionally wet conditions, driven by changes in location and strength of the mid-latitude winter storm track. The distribution of modern winter precipitation is frequently characterized by a north-south wet/dry dipole pattern, controlled by interaction of the storm track with ocean-atmosphere conditions over the PaciEstablishing chronologies for alluvial-fan sequences with analysis of high-resolution topographic data: San Luis Valley, Colorado, USA
On active alluvial fans, debris-flow deposits and frequent avulsions produce a rough topographic surface. As is the case in many initially rough landforms produced by catastrophic processes, the topography of alluvial fans is progressively smoothed, producing textural differences useful in establishing relative age criteria for fans. Here, we outline an approach for defining a quantitative, numeriIsotopic characterization of late Neogene travertine deposits at Barrancas Blancas in the eastern Atacama Desert, Chile
Here we explore the potential of spring-related, surface and subsurface carbonates as an archive of paleoenvironmental change at Barrancas Blancas, located in the broadest and driest sector of the Atacama Desert at 24.5°S. From these deposits we present a new stable isotopic record of paleoenvironmental conditions over portions of the past ~ 11.5 Ma. U-Pb dates from the carbonates, both surface anStable C, O and clumped isotope systematics and 14C geochronology of carbonates from the Quaternary Chewaucan closed-basin lake system, Great Basin, USA: Implications for paleoenvironmental reconstructions using carbonates
Isotopic compositions of lacustrine carbonates are commonly used for dating and paleoenvironmental reconstructions. Here we use carbonate δ13C and δ18O, clumped (Δ47), and 14C compositions to better understand the carbonate isotope system in closed-basin lakes and trace the paleohydrologic and temperature evolution in the Chewaucan closed-basin lake system, northern Great Basin, USA, over the LastPreliminary geologic map of the Big Costilla Peak area, Taos County, New Mexico, and Costilla County, Colorado
This map covers the Big Costilla Peak, New Mex.‒Colo. quadrangle and adjacent parts of three other 7.5 minute quadrangles: Amalia, New Mex.‒Colo., Latir Peak, New Mex., and Comanche Point, New Mex. The study area is in the southwesternmost part of that segment of the Sangre de Cristo Mountains known as the Culebra Range; the Taos Range segment lies to the southwest of Costilla Creek and its tributPreliminary geologic map of the Vermejo Peak area, Colfax and Taos Counties, New Mexico and Las Animas and Costilla Counties, Colorado
This geologic map covers four 7.5-minute quadrangles-The Wall, NM-CO (New Mexico-Colorado), Vermejo Park, NM-CO, Ash Mountain, NM, and Van Bremmer Park, NM. The study area straddles the boundary between the eastern flank of the Sangre de Cristo Mountains and the western margin of the Raton Basin, with about two-thirds of the map area in the basin. The Raton Basin is a foreland basin that formed imNon-USGS Publications**
Licht, A., Quade, J., Kowler, A., de Los Santos, M., Hudson, A., Schauer, A., Huntington, K., Copeland, P., Lawton, T., 2017. Impact of the North American monsoon on isotope paleoaltimeters: implications for the paleoaltimetry of the American Southwest. American Journal of Science 317, 1-33.Conroy, J.L, Hudson, A.M., Overpeck, J.T., Liu K.-B., Wang L., 2017. The primacy of multidecadal to centennial variability of late-Holocene forced change of the Asian Monsoon on the southern Tibetan Plateau. Earth and Planetary Science Letters 458, 337-348.Hudson, A.M., Olsen, J.W., Quade, J., Lei G., Huth, T.E., Zhang H., 2016. A regional record of expanded Holocene wetlands and prehistoric human occupation from paleowetland deposits of the western Yarlung Tsangpo valley, Tibetan Plateau. Quaternary Research 86, 13-33.Perreault, C., Boulanger, M.T., Hudson, A.M., Rhode, D., Madsen, D.B., Olsen, J.W., Steffen, M.L., Quade, J., Glascock, M.D., Brantingham, P.J., 2016. Characterization of obsidian from the Tibetan Plateau by XRF and NAA. Journal of Archaeological Science: Reports 5, 392-399.Phillips, F.M., Kelly, M.A., Hudson, A.M., Stone, J.O.H., Schaefer, J., Marrero, S., Fifield, K., Finkel, R., Lowell, T.V., 2016, CRONUS-Earth calibrations samples from the Huancané moraines, Quelccaya Ice Cap, Peru. Quaternary Geochronology, 31, 220-236.
Phillips, F.M., Argento, D.C., Balco, G., Caffee, M.W., Clem, J., Dunai, T.J., Finkel, R., Goehring, B., Gosse, J.C., Hudson, A.M., Jull, A.J.T., Kelly, M.A., Kurz, M., Lal, D., Lifton, N., Marrero, S.M., Nishiizumi, K., Reedy, R.C., Schaefer, J., Stone, J.O.H., Swanson, T., Zreda, M.G., 2016, The CRONUS-Earth project: a synthesis. Quaternary Geochronology 31, 119-154.Phillips, F.M., Argento, D.C., Bourles, D.L., Caffee, M.W., Dunai, T.J., Goehring, B., Gosse, J.C., Hudson, A.M., Jull, A.J.T., Kelly, M., Lifton, N., Marrero, S.M., Nishiizumi, K., Reedy, R.C., Stone, J.O.H., 2016, Where now? Reflections on future directions for cosmogenic nuclide research from the CRONUS Projects. Quaternary Geochronology 31, 155-159.Hudson, A.M., Quade, J., Huth, T.E., Lei G., Cheng H., Edwards, R.L., Olsen, J.W., and Zhang H., 2015, Lake level reconstruction for 12.8-2.3 ka for the Ngangla Ring Tso closed-basin lake system, southwest Tibetan Plateau. Quaternary Research 83, 66-79.Huth, T.E., Hudson, A.M., Quade J., Lei G., and Zhang H., 2015, Paleohydrologic reconstruction of Holocene climate 11.5-5.0 ka based on shoreline dating and hydrologic budget modeling of Baqan Tso, southwestern Tibetan Plateau. Quaternary Research 83, 80-93.Grimstead, D.N., Reynolds, A.C., Hudson, A.M., Akins, N.J., Betancourt, J.L., 2015, Low 87Sr/86Sr variance in turkey remains reveal domestication at Chaco Canyon. Journal of Archaeological Methods and Theory 23, 127-149Hudson, A.M., Olsen, J.W., and Quade, J., 2014, Radiocarbon dating of interdune paleowetland deposits to constrain the age of mid- to Late Holocene microlithic artifacts from the Zhongba site, southwestern Qinghai-Tibet Plateau. Geoarchaeology 29, 33-46.Huntington, K.W., Saylor, J., Quade, J., and Hudson, A.M., 2015, New constraints on Tibetan Plateau uplift from carbonate clumped isotope thermometry. Geological Society of America Bulletin 127, 181-199.Kelly, M.A., Lowell, T.V., Applegate, P.J., Phillips, F.M., Schaefer, J.M., Smith, C.A., Kim, H., Leonard, K., and Hudson, A.M., 2015, A locally calibrated late glacial 10Be production rate from a low-latitude, high-altitude site in the Peruvian Andes: Quaternary Geochronology 26, 70-85Hudson, A.M., and Quade, J., 2013, Long-term asymmetry in monsoon climate on the Tibetan Plateau: Geology 41, 351-354.Kelly, M.A., Lowell, T.V., Applegate, P.J., Smith, C.A., Phillips, F.M., and Hudson, A.M., 2012, Late glacial fluctuations of Quelccaya Ice Cap, southeastern Peru: Geology 40, 991-994.Pelletier, J.D., Engelder, T.M., Comeau, D., Hudson, A., Leclerc, M., Youberg, A., and Diniega, S., 2009. Tectonic and structural control of fluvial channel morphology in metamorphic core complexes: The example of the Catalina-Rincon core complex, Arizona, Geosphere, 5, 363-384.**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.