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Articles 1 - 14 of 14
Full-Text Articles in Physical Sciences and Mathematics
Pace And Process Of Active Folding And Fluvial Incision Across The Kantishna Hills Anticline, Central Alaska, A. M. Bender, R. O. Lease, P. J. Haeussler, Tammy M. Rittenour, L. B. Corbett, P. R. Bierman, M. W. Caffee
Pace And Process Of Active Folding And Fluvial Incision Across The Kantishna Hills Anticline, Central Alaska, A. M. Bender, R. O. Lease, P. J. Haeussler, Tammy M. Rittenour, L. B. Corbett, P. R. Bierman, M. W. Caffee
Geosciences Faculty Publications
Rates of northern Alaska Range thrust system deformation are poorly constrained. Shortening at the system's west end is focused on the Kantishna Hills anticline. Where the McKinley River cuts across the anticline, the landscape records both Late Pleistocene deformation and climatic change. New optically stimulated luminescence and cosmogenic 10Be depth profile dates of three McKinley River terrace levels (~22, ~18, and ~14–9 ka) match independently determined ages of local glacial maxima, consistent with climate‐driven terrace formation. Terrace ages quantify rates of differential bedrock incision, uplift, and shortening based on fault depth inferred from microseismicity. Differential rock uplift and incision (≤1.4 …
Assessing Ground Penetrating Radar's Ability To Image Subsurface Characteristics Of Icy Debris Fans In Alaska And New Zealand, Robert W. Jacob, Jeffrey M. Trop, R. Craig Kochel
Assessing Ground Penetrating Radar's Ability To Image Subsurface Characteristics Of Icy Debris Fans In Alaska And New Zealand, Robert W. Jacob, Jeffrey M. Trop, R. Craig Kochel
Faculty Journal Articles
Icy debris fans have recently been described as fan shaped depositional landforms associated with (or formed during) deglaciation, however, the subsurface characteristics remain essentially undocumented. We used ground penetrating radar (GPR) to non-invasively investigate the subsurface characteristics of icy debris fans (IDFs) at McCarthy Glacier, Alaska, USA and at La Perouse Glacier, South Island of New Zealand. IDFs are largely unexplored paraglacial landforms in deglaciating alpine regions at the mouths of bedrock catchments between valley glaciers and icecaps. IDFs receive deposits of mainly ice and minor lithic material through different mass-flow processes, chiefly ice avalanche and to a lesser extent …
The 2015 Landslide And Tsunami In Taan Fiord, Alaska, Bretwood Higman, Breanyn Macinnes, Colin Bloom
The 2015 Landslide And Tsunami In Taan Fiord, Alaska, Bretwood Higman, Breanyn Macinnes, Colin Bloom
All Faculty Scholarship for the College of the Sciences
Glacial retreat in recent decades has exposed unstable slopes and allowed deep water to extend beneath some of those slopes. Slope failure at the terminus of Tyndall Glacier on 17 October 2015 sent 180 million tons of rock into Taan Fiord, Alaska. The resulting tsunami reached elevations as high as 193 m, one of the highest tsunami runups ever documented worldwide. Precursory deformation began decades before failure, and the event left a distinct sedimentary record, showing that geologic evidence can help understand past occurrences of similar events, and might provide forewarning. The event was detected within hours through automated seismological …
Alaskan Marine Transgressions Record Out-Of-Phase Arctic Ocean Glaciation During The Last Interglacial, Louise Farquharson, Daniel Mann, Tammy M. Rittenour, Pamela Groves, Guido Grosse, Benjamin Jones
Alaskan Marine Transgressions Record Out-Of-Phase Arctic Ocean Glaciation During The Last Interglacial, Louise Farquharson, Daniel Mann, Tammy M. Rittenour, Pamela Groves, Guido Grosse, Benjamin Jones
Geosciences Faculty Publications
Ongoing climate change focuses attention on the Arctic cryosphere’s responses to past and future climate states. Although it is now recognized the Arctic Ocean Basin was covered by ice sheets and their associated floating ice shelves several times during the Late Pleistocene, the timing and extent of these polar ice sheets remain uncertain. Here we relate a relict barrier-island system on the Beaufort Sea coast of northern Alaska to the isostatic effects of a previously unrecognized ice shelf grounded on the adjacent continental shelf. A new suite of optically stimulated luminescence dates show that this barrier system formed during one …
Geomorphology Of Icy Debris Fans: Delivery Of Ice And Sediment To Valley Glaciers Decoupled From Icecaps, R. Craig Kochel, Jeffrey M. Trop, Robert W. Jacob
Geomorphology Of Icy Debris Fans: Delivery Of Ice And Sediment To Valley Glaciers Decoupled From Icecaps, R. Craig Kochel, Jeffrey M. Trop, Robert W. Jacob
Faculty Journal Articles
The pace and volume of mass flow processes contributing ice and sediment to icy debris fans (IDFs) were documented at sites in Alaska and New Zealand by integrating field observations, drone and time-lapse imagery, ground penetrating radar, and terrestrial laser scanning. Largely unstudied, IDFs are supraglacial landforms at the mouths of bedrock catchments between valley glaciers and icecaps. Time-lapse imagery recorded 300–2300 events reaching 15 fans during intervals from nine months to two years. Field observations noted hundreds of deposits trapped within catchments weekly that were later remobilized onto fans. Deposits were mapped on images taken three to four times …
Topography Of The Mantle Transition Zone Discontinuities Beneath Alaska And Its Geodynamic Implications: Constraints From Receiver Function Stacking, Haider H. Dahm, Stephen S. Gao, Fansheng Kong, Kelly H. Liu
Topography Of The Mantle Transition Zone Discontinuities Beneath Alaska And Its Geodynamic Implications: Constraints From Receiver Function Stacking, Haider H. Dahm, Stephen S. Gao, Fansheng Kong, Kelly H. Liu
Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works
The 410 and 660 km discontinuities (d410 and d660, respectively) beneath Alaska and adjacent areas are imaged by stacking 75,296 radial receiver functions recorded by 438 broadband seismic stations with up to 30 years of recording period. When the 1-D IASP91 Earth model is used for moveout correction and time depth conversion, significant and spatially systematic variations in the apparent depths of the d410 and d660 are observed. The mean apparent depth of the d410 and d660 for the entire study area is 417 ± 12 km and 665 ± 12 km, respectively, and the mean mantle transition zone (MTZ) …
Geochemical Evidence For Seasonal Controls On The Transportation Of Holocene Loess, Matanuska Valley, Southern Alaska, Usa, Daniel R. Muhs, James R. Budahn, Gary Skipp, John P. Mcgeehin
Geochemical Evidence For Seasonal Controls On The Transportation Of Holocene Loess, Matanuska Valley, Southern Alaska, Usa, Daniel R. Muhs, James R. Budahn, Gary Skipp, John P. Mcgeehin
United States Geological Survey: Staff Publications
Loess is a widespread Quaternary deposit in Alaska and loess accretion occurs today in some regions, such as the Matanuska Valley. The source of loess in the Matanuska Valley has been debated for more than seven decades, with the Knik River and the Matanuska River, both to the east, being the leading candidates and the Susitna River, to the west, as a less favorable source. We report here new stratigraphic, mineralogic, and geochemical data that test the competing hypotheses of these river sources. Loess thickness data are consistent with previous studies that show that a source or sources lay to …
Using Satellite Image Analysis For Locating Prehistoric Archaeological Sites In Alaska's Central Brooks Range, Robert Hickey, J. Keeney
Using Satellite Image Analysis For Locating Prehistoric Archaeological Sites In Alaska's Central Brooks Range, Robert Hickey, J. Keeney
Geography Faculty Scholarship
In this pilot study, we apply satellite image analysis to archaeological site prospection in Alaska's Brooks Range. Our goal was to test whether satellite remote sensing, which has been successful in locating large archaeological features associated with sedentary peoples, could be applied to arctic interior sites associated with mobile hunter–gatherers. In particular, we strove to develop a relatively straightforward and inexpensive model using existing data which could be used to help guide archaeology surveys. Using 1-m resolution IKONOS imagery of Lake Matcharak along the upper Noatak River, we produced a Normalized Difference Vegetation Index (NDVI) and tasseled cap transformation of …
Loess Origin, Transport, And Deposition Over The Past 10,000 Years, Wrangell-St. Elias National Park, Alaska, Daniel R. Muhs, James R. Budahn, John P. Mcgeehin, E. Arthur Bettis Iii, Gary Skipp, James B. Paces, Elisabeth A. Wheeler
Loess Origin, Transport, And Deposition Over The Past 10,000 Years, Wrangell-St. Elias National Park, Alaska, Daniel R. Muhs, James R. Budahn, John P. Mcgeehin, E. Arthur Bettis Iii, Gary Skipp, James B. Paces, Elisabeth A. Wheeler
United States Geological Survey: Staff Publications
Contemporary glaciogenic dust has not received much attention, because most research has been on glaciogenic dust of the last glacial period or non-glaciogenic dust of the present interglacial period. Nevertheless, dust from modern glaciogenic sources may be important for Fe inputs to primary producers in the ocean. Adjacent to the subarctic Pacific Ocean, we studied a loess section near Chitina, Alaska along the Copper River in Wrangell-St. Elias National Park, where dust has been accumulating over the past ~10,000 years. Mass accumulation rates for the fine-grained (<20 >µm) fraction of this loess section are among the highest reported for the …
Ice-Age Megafauna In Arctic Alaska: Extinction, Invasion, Survival, Daniel H. Mann, Pamela Groves, Michael L. Kunz, Richard E. Reanier, Benjamin V. Gaglioti
Ice-Age Megafauna In Arctic Alaska: Extinction, Invasion, Survival, Daniel H. Mann, Pamela Groves, Michael L. Kunz, Richard E. Reanier, Benjamin V. Gaglioti
United States Geological Survey: Staff Publications
Radical restructuring of the terrestrial, large mammal fauna living in arctic Alaska occurred between 14,000 and 10,000 years ago at the end of the last ice age. Steppe bison, horse, and woolly mammoth became extinct, moose and humans invaded, while muskox and caribou persisted. The ice age mega fauna was more diverse in species and possibly contained 6x more individual animals than live in the region today. Mega faunal biomass during the last ice age may have been 30x greater than present. Horse was the dominant species in terms of number of individuals. Lions, short-faced bears, wolves, and possibly grizzly …
From Sink To Resurgence: The Buffering Capacity Of A Cave System In The Tongass National Forest, Usa, Chris Groves, Melissa Hendrikson
From Sink To Resurgence: The Buffering Capacity Of A Cave System In The Tongass National Forest, Usa, Chris Groves, Melissa Hendrikson
Earth, Environmental, and Atmospheric Sciences Faculty Publications
The Tongass National Forest of Southeast Alaska, USA, provides a unique environment for monitoring the impact of the cave system on water quality and biological productivity. The accretionary terrane setting of the area has developed into a complex and heterogeneous geologic landscape which includes numerous blocks of limestone with intense karstification. During the Wisconsian glaciation, there were areas of compacted glacial sediments and silts deposited over the bedrock. Muskeg peatlands developed over these poorly drained areas. The dominant plants of the muskeg ecosystem are Sphagnum mosses, whose decomposition leads to highly acidic waters with pH as low as 2.4. These …
Storm Response And Water Balance Of Temperate Rainforest Karst Watersheds: Tongass National Forest, Alaska, Johanna Kovarik
Storm Response And Water Balance Of Temperate Rainforest Karst Watersheds: Tongass National Forest, Alaska, Johanna Kovarik
Masters Theses & Specialist Projects
The Tongass National Forest in southeast Alaska contains 2,176 square kilometers of karst. As part of the evolving Tongass Land Management Plan, research into the function of karst systems is crucial in understanding how forest management affects not only karst areas but also surrounding ecosystems. Dye trace and water balance results in two watersheds on the north end of Prince of Wales Island demonstrate the difficulty in containing the effects of management, as water can enter karst catchments from unknown sources at different flow regimes. A dye trace was conducted in Windgate and Canyon Block watersheds. Two sinking streams were …
Arctic Gold, Alaska, Joel Halpern
Arctic Gold, Alaska, Joel Halpern
Emeritus Faculty Author Gallery
To armchair travelers, especially in the United States, few places have a stronger allure than far-off Alaska. Now that the "wild and woolly" west is really alive only so far as it serves to accentuate our historical heritage, this land of the far north has become our last frontier. To the geologist, mineralogist, and, I might add, even to the layman, one of the most interesting features of the territory is its large placer gold deposits. Every American boy has heard of the Nome gold rush, and the more literarily adventurous have undoubtedly delved into the sagas of Jack London. …
Arctic Gold, Joel Halpern
Arctic Gold, Joel Halpern
Anthropology Department Faculty Publication Series
To armchair travelers, especially in the United States, few places have a stronger allure than far-off Alaska. Now that the "wild and woolly" west is really alive only so far as it serves to accentuate our historical heritage, this land of the far north has become our last frontier. To the geologist, mineralogist, and, I might add, even to the layman, one of the most interesting features of the territory is its large placer gold deposits. Every American boy has heard of the Nome gold rush, and the more literarily adventurous have undoubtedly delved into the sagas of Jack London. …