J. W. Holt
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View article: Stratigraphic evidence for modern‐like glacier extents in south‐central Alaska within the last glacial period ( <scp>MIS</scp> 3)
Stratigraphic evidence for modern‐like glacier extents in south‐central Alaska within the last glacial period ( <span>MIS</span> 3) Open
The last (Wisconsinan) glacial period was punctuated in North America by two glacial maxima, known as the Early and Late Wisconsinan glaciations. In Alaska, these maxima and their subsequent retreats have been the object of dating efforts …
View article: Alaskan Glacier Depths from a Decade of Airborne Radar Sounding
Alaskan Glacier Depths from a Decade of Airborne Radar Sounding Open
NASA’s Operation IceBridge employed airborne radar sounders in Alaska and adjacent northwestern Canada between 2012-2021 to measure the thickness of the region’s glaciers. Here we present the first comprehensive analysis of these data, pro…
View article: The demise of the world's largest piedmont glacier: a probabilistic forecast
The demise of the world's largest piedmont glacier: a probabilistic forecast Open
Sít' Tlein, located in the St. Elias Range, which straddles Alaska's Wrangell–St. Elias National Park and Kluane National Park in the Yukon, is the world's largest piedmont glacier. Sít' Tlein has thinned considerably over 30 years of alti…
View article: A century of flow and surge history of Sít’ Tlein(Malaspina Glacier), Southeast Alaska
A century of flow and surge history of Sít’ Tlein(Malaspina Glacier), Southeast Alaska Open
Sít' Tlein (Malaspina Glacier), located in Southeast Alaska, has a complex flow history. This piedmont glacier, the largest in the world of its kind, is fed by three main tributaries that all exhibit similar flow patterns, yet with varying…
View article: A century of flow and surge history of Sít’ Tlein (Malaspina Glacier), Southeast Alaska
A century of flow and surge history of Sít’ Tlein (Malaspina Glacier), Southeast Alaska Open
Sít’ Tlein (Malaspina Glacier), located in Southeast Alaska, has a complex flow history. This piedmont glacier, the largest in the world, is fed by three main tributaries that all exhibit similar flow patterns, yet with varying surge cycle…
View article: The demise of the world's largest piedmont glacier: a probabilistic forecast
The demise of the world's largest piedmont glacier: a probabilistic forecast Open
Sít' Tlein in Alaska's St. Elias Range (briefly known as Malaspina Glacier) is the world's largest piedmont glacier and has thinned considerably over 30 years of altimetry, yet it's low-elevation piedmont lobe has remained intact in contra…
View article: Subsurface Investigations of Debris-Covered Glaciers as Mars Analogs with Drone-Based Ground Penetrating Radar
Subsurface Investigations of Debris-Covered Glaciers as Mars Analogs with Drone-Based Ground Penetrating Radar Open
Ground penetrating radar (GPR) is a valuable geophysical technology for imaging the interior of debris-covered glaciers (DCGs) on Mars and Earth. The Shallow Radar (SHARAD, 15-25 MHz) sounder onboard NASA’s Mars Reconnaissance Orbite…
View article: The Fluvial and Volcanic History of Hebrus Valles and Hephaestus Fossae on Mars
The Fluvial and Volcanic History of Hebrus Valles and Hephaestus Fossae on Mars Open
IntroductionHebrus Valles (HV) and Hephaestus Fossae (HF) are well-preserved Early Amazonian outflow channel systems carved into bedrock in SE Utopia Planitia, Mars (17-25 °N, 118-129 °E, Fig. 1). They exhibit a diverse set of mo…
View article: Synchrotron X-ray diffraction for sealed Mars Sample Return sample tubes
Synchrotron X-ray diffraction for sealed Mars Sample Return sample tubes Open
Introduction: NASA and ESA are collaborating on a Mars Sample Return (MSR) mission which aims to retrieve drill cores of Martian rock for terrestrial analysis, from Jezero Crater and the Perseverance Rover. Up to 30 samples, inside sealed …
View article: Thickness of Ruth Glacier, Alaska, and depth of its Great Gorge from ice-penetrating radar and mass conservation
Thickness of Ruth Glacier, Alaska, and depth of its Great Gorge from ice-penetrating radar and mass conservation Open
Ruth Glacier is situated in the Central Alaska Range, with the Don Sheldon Amphitheater comprising much of its broad accumulation area, directly adjacent to North America's tallest mountain, Denali. From there it funnels through the ‘Great…
View article: Active Seismic Refraction, Reflection, and Surface‐Wave Surveys in Thick Debris‐Covered Glacial Environments
Active Seismic Refraction, Reflection, and Surface‐Wave Surveys in Thick Debris‐Covered Glacial Environments Open
Debris‐covered glaciers (DCG) and rock glaciers have been increasingly studied in recent years because of the role they play within local watersheds, glacial ablation models due to climate change, and as analogs for buried ice features on …
View article: Revealing Elysium Planitia's Young Geologic History: Constraints on Lava Emplacement, Areas, and Volumes
Revealing Elysium Planitia's Young Geologic History: Constraints on Lava Emplacement, Areas, and Volumes Open
Elysium Planitia includes several outflow channels that were likely carved by aqueous erosion and subsequently infilled by younger lava flows, making Elysium Planitia the youngest volcanic terrain on Mars. Studying this region is critical …
View article: Subsurface scientific exploration of extraterrestrial environments (MINAR 5): analogue science, technology and education in the Boulby Mine, UK – CORRIGENDUM
Subsurface scientific exploration of extraterrestrial environments (MINAR 5): analogue science, technology and education in the Boulby Mine, UK – CORRIGENDUM Open
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View article: Active Seismic Refraction, Reflection and Surface-Wave Surveys in Thick Debris-Covered Glacial Environments
Active Seismic Refraction, Reflection and Surface-Wave Surveys in Thick Debris-Covered Glacial Environments Open
Debris-covered glaciers and rock glaciers have been increasingly studied in recent years because of the role they play within local watersheds, glacial ablation models due to climate change, and as analogs for buried ice features on planet…
View article: Evidence of Widespread Volcanic Activity near Hebrus Valles on Mars Revealed by SHARAD
Evidence of Widespread Volcanic Activity near Hebrus Valles on Mars Revealed by SHARAD Open
Hebrus Valles is an outflow channel system in the plain-forming terrains of southeastern Utopia Planitia, Mars. These terrains may have formed through a combination of liquid water and volcanic processes, yet their nature, subsurface struc…
View article: Photogrammetric Monitoring of Rock Glacier Motion Using High-Resolution Cross-Platform Datasets: Formation Age Estimation and Modern Thinning Rates
Photogrammetric Monitoring of Rock Glacier Motion Using High-Resolution Cross-Platform Datasets: Formation Age Estimation and Modern Thinning Rates Open
The availability of remote sensing imagery at high spatiotemporal resolutions presents the opportunity to monitor the surface motion of rock glaciers, a key constraint for characterizing the dynamics of their evolution. In this paper, we i…
View article: I. Detailed Records of Geomagnetic Field Behavior from Death Valley and Hawaii. II. An Age Constraint on Gulf of California Rifting from Santa Rosalía, Baja California
I. Detailed Records of Geomagnetic Field Behavior from Death Valley and Hawaii. II. An Age Constraint on Gulf of California Rifting from Santa Rosalía, Baja California Open
Detailed records of geomagnetic field behavior were produced and analyzed from Plio/Pleistocene sedimentary rocks of Death Valley, California and from Pleistocene/Holocene volcanic rocks of Hawaii. These records provide new information abo…
View article: Antarctic Bedmap data: Findable, Accessible, Interoperable, and Reusable (FAIR) sharing of 60 years of ice bed, surface, and thickness data
Antarctic Bedmap data: Findable, Accessible, Interoperable, and Reusable (FAIR) sharing of 60 years of ice bed, surface, and thickness data Open
One of the key components of this research has been the mapping of Antarctic bed topography and ice thickness parameters that are crucial for modelling ice flow and hence for predicting future ice loss and the ensuing sea level rise. Suppo…
View article: Synchrotron X-ray Diffraction for Early Characterisation of Sealed Mars2020 Samples
Synchrotron X-ray Diffraction for Early Characterisation of Sealed Mars2020 Samples Open
NASA, ESA and the UK are collaborating on a Mars Sample Return (MSR) mission which aims to retrieve drill cores of Martian rock for terrestrial analysis, starting with the Mars2020 rover which landed successfully in Jezero Crater in Feb. 2…
View article: Comprehensive Radar Mapping of Malaspina Glacier (Sít' Tlein), Alaska—The World's Largest Piedmont Glacier—Reveals Potential for Instability
Comprehensive Radar Mapping of Malaspina Glacier (Sít' Tlein), Alaska—The World's Largest Piedmont Glacier—Reveals Potential for Instability Open
Malaspina Glacier, located on the coast of southern Alaska, is the world's largest piedmont glacier. A narrow ice‐cored foreland zone undergoing rapid thermokarst erosion separates the glacier from the relatively warm waters of the Gulf of…
View article: Comment on essd-2022-355
Comment on essd-2022-355 Open
Abstract. Over the past 60 years, scientists have strived to understand the past, present and future of the Antarctic Ice Sheet. One of the key components of this research has been the mapping of Antarctic bed topography and ice thickness …
View article: Antarctic Bedmap data: FAIR sharing of 60 years of ice bed, surface and thickness data
Antarctic Bedmap data: FAIR sharing of 60 years of ice bed, surface and thickness data Open
Over the past 60 years, scientists have strived to understand the past, present and future of the Antarctic Ice Sheet. One of the key components of this research has been the mapping of Antarctic bed topography and ice thickness parameters…
View article: New Views of the Internal Structure of Planum Boreum from Enhanced 3D Imaging of Mars Reconnaissance Orbiter Shallow Radar Data
New Views of the Internal Structure of Planum Boreum from Enhanced 3D Imaging of Mars Reconnaissance Orbiter Shallow Radar Data Open
We present first results from a new 3D radargram produced from 3399 Mars Reconnaissance Orbiter (MRO) Shallow Radar observations of the north polar region of Mars. While incorporating an additional 5 yr of observations relative to the prio…
View article: Rock glacier composition and structure from radio wave speed analysis with dipping reflector correction
Rock glacier composition and structure from radio wave speed analysis with dipping reflector correction Open
We assess the composition and geometry of four individual rock glaciers in Alaska, Wyoming and Colorado by measuring their radio wave speed and applying these results to ground-penetrating radar depth corrections and dielectric mixing mode…
View article: The north polar basal unit of Mars: An Amazonian record of surface processes and climate events
The north polar basal unit of Mars: An Amazonian record of surface processes and climate events Open
The basal unit is a sedimentary deposit of water ice and lithic fines lying within the Planum Boreum of Mars. It can be divided into two subunits, rupēs and cavi, based on their stratigraphy and age. The basal unit lies between Late Hesper…
View article: The Scientific Legacy of NASA’s Operation IceBridge
The Scientific Legacy of NASA’s Operation IceBridge Open
The National Aeronautics and Space Administration (NASA)’s Operation IceBridge (OIB) was a 13‐year (2009–2021) airborne mission to survey land and sea ice across the Arctic, Antarctic, and Alaska. Here, we review OIB’s goals, instruments, …