Journal articles: 'Glaciers – Montana'

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Ferrigno, Jane G. "Recession of Grasshopper Glacier, Montana, Since 1898." Annals of Glaciology 8 (1986): 65–68. http://dx.doi.org/10.3189/s0260305500001154.

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Grasshopper Glacier is a cirque glacier in the central Rocky Mountains of the United States. It is a remnant of the “Little Ice Age”, rather than the more widespread and older Pinedale Glaciation. The glacier has not been monitored on a regular basis and very few maps have been published of the area, but it has been studied, photographed, occasionally mapped, and described by scientific and non-scientific groups, at different times since 1898. These photographic, cartographic, and written records make it possible to trace the fluctuations of this glacier since 1898. Grasshopper Glacier has had periods of positive mass balance, but the overall trend has been negative, with accelerated melting in recent years. It is estimated that Grasshopper Glacier has lost about 50% of its area and as much as 90% of its volume, since 1898. Other Rocky Mountain glaciers are experiencing similar wastage and, if current conditions continue, these glaciers will disappear by the middle of the next century.

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Ferrigno, Jane G. "Recession of Grasshopper Glacier, Montana, Since 1898." Annals of Glaciology 8 (1986): 65–68. http://dx.doi.org/10.1017/s0260305500001154.

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Grasshopper Glacier is a cirque glacier in the central Rocky Mountains of the United States. It is a remnant of the “Little Ice Age”, rather than the more widespread and older Pinedale Glaciation. The glacier has not been monitored on a regular basis and very few maps have been published of the area, but it has been studied, photographed, occasionally mapped, and described by scientific and non-scientific groups, at different times since 1898. These photographic, cartographic, and written records make it possible to trace the fluctuations of this glacier since 1898. Grasshopper Glacier has had periods of positive mass balance, but the overall trend has been negative, with accelerated melting in recent years. It is estimated that Grasshopper Glacier has lost about 50% of its area and as much as 90% of its volume, since 1898. Other Rocky Mountain glaciers are experiencing similar wastage and, if current conditions continue, these glaciers will disappear by the middle of the next century.

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Goff, Paepin, and David R. Butler. "James Dyson (1948) Shrinkage of Sperry and Grinnell Glaciers, Glacier National Park, Montana. Geographical Review 38(1): 95–103." Progress in Physical Geography: Earth and Environment 40, no. 4 (June 30, 2016): 616–21. http://dx.doi.org/10.1177/0309133316652820.

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A warming climate is melting the namesake glaciers of Glacier National Park, Montana, USA. James Dyson’s 1948 paper was one of the earliest publications to emphasize climate change impacts to the cryosphere through an examination of Sperry and Grinnell Glaciers. This paper, combined with his subsequent works, acts as a pillar for current glacier monitoring efforts.

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Carrara, Paul E. "Holocene and latest Pleistocene glacial chronology, Glacier National Park, Montana." Canadian Journal of Earth Sciences 24, no. 3 (March 1, 1987): 387–95. http://dx.doi.org/10.1139/e87-041.

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Moraines of two different age groups have been identified fronting the present-day glaciers and snowfields in Glacier National Park, Montana. The subdued, vegetated moraines of the older group have been found at 25 sites, mainly in the central part of the Lewis Range. These older moraines are in places overlain by the Mazama ash. Although the exact age of the moraines has not been determined by radiocarbon dating, vegetative evidence and correlation with other pre-altithermal age moraines in the Rocky Mountains suggest that these older moraines date from 10 000 BP or earlier. Whether these moraines are the product of a separate advance after the end of the Wisconsin glaciation or are simply the product of the last advance or stillstand of Wisconsin glaciers before final deglaciation is not known.Moraines of the younger group, consisting of fresh bouldery rubble, are common throughout Glacier Park. Tree-ring analyses indicate that some of these younger moraines were deposited by advances that culminated during the mid-19th century. At that time there were more than 150 glaciers in Glacier Park. This episode of mid-19th century climatic cooling resulted in the most extensive glacial advance in this region since the end of the Wisconsin glaciation.Present-day glaciers have shrunk drastically from their mid-19th century positions; more than half the glaciers present during that time no longer exist. Much of this retreat occurred between 1920 and the mid-1940's, corresponding to a period of above-average summer temperatures and below-average annual precipitation in this region. Between 1966 and 1979, several of the larger glaciers in the Mount Jackson area of Glacier Park advanced as much as 100 m.

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Florentine, Caitlyn, Mark Skidmore, Marvin Speece, Curtis Link, and Colin A. Shaw. "Geophysical analysis of transverse ridges and internal structure at Lone Peak Rock Glacier, Big Sky, Montana, USA." Journal of Glaciology 60, no. 221 (2014): 453–62. http://dx.doi.org/10.3189/2014jog13j160.

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AbstractRock glaciers are periglacial alpine landforms that are found in many locations worldwide. Whereas well-developed models of deformation are established for traditional alpine glaciers, rock glacier deformation is poorly understood. Geophysical data from Lone Peak Rock Glacier (LPRG), southwest Montana, USA, are paired with lidar bare-earth 1 m digital elevation model (DEM) analysis to explore potential genetic relationships between internal composition, structure and regularly spaced arcuate transverse ridges expressed at the rock glacier surface. The internal composition of LPRG is heterogeneous, with frozen debris and clean ice overlain by an unconsolidated talus mantle. Upslope-dipping, clearly distinguished reflectors in the ground-penetrating radar (GPR) longitudinal survey at LPRG correspond to transverse ridges. The spacing and slope of individual features at the surface and in the subsurface were measured and compared and are found to be similar. The structures observed at LPRG and other rock glaciers are similar to structures detected in glaciotectonically altered sediment, ice-cored moraines and other rock glacier settings. This finding suggests that transverse ridges on rock glaciers may be used as geomorphic indicators of internal deformation. This study contributes to the body of research on the application of GPR to rock glaciers, and is the first to directly pair and analyze individual surface topographic features with internal structures.

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Allen, Thomas R. "Topographic context of glaciers and perennial snowfields, Glacier National Park, Montana." Geomorphology 21, no. 3-4 (January 1998): 207–16. http://dx.doi.org/10.1016/s0169-555x(97)00059-7.

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Johnson, Gunnar, Heejun Chang, and Andrew Fountain. "Active rock glaciers of the contiguous United States: geographic information system inventory and spatial distribution patterns." Earth System Science Data 13, no. 8 (August 17, 2021): 3979–94. http://dx.doi.org/10.5194/essd-13-3979-2021.

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Abstract. In this study we present the Portland State University Active Rock Glacier Inventory (n=10 332) for the contiguous United States, derived from the manual classification of remote sensing imagery (Johnson, 2020; https://doi.org/10.1594/PANGAEA.918585). Individually, these active rock glaciers are found across widely disparate montane environments, but their overall distribution unambiguously favors relatively high, arid mountain ranges with sparse vegetation. While at least one active rock glacier is identified in each of the 11 westernmost states, nearly 88 % are found in just five states: Colorado (n=3889), Montana (n=1813), Idaho (n=1689), Wyoming (n=839), and Utah (n=834). Mean active rock glacier area is estimated at 0.10 km2, with cumulative active rock glacier area totaling 1004.05 km2. Active rock glaciers are assigned to a three-tier classification system based on area thresholds and surface characteristics known to correlate with downslope movement. Class 1 features (n=7042, average area = 0.12 km2) appear to be highly active, Class 2 features (n=2415, average area = 0.05 km2) appear to be intermediately active, and Class 3 features (n=875, average area = 0.04 km2) appear to be minimally active. This geospatial inventory will allow past active rock glacier research findings to be spatially extrapolated, help facilitate further active rock glacier research by identifying field study sites, and serve as a valuable training set for the development of automated rock glacier identification and classification methods applicable to other large regional studies.

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Clark, Adam M., Daniel B. Fagre, Erich H. Peitzsch, Blase A. Reardon, and Joel T. Harper. "Glaciological measurements and mass balances from Sperry Glacier, Montana, USA, years 2005–2015." Earth System Science Data 9, no. 1 (January 23, 2017): 47–61. http://dx.doi.org/10.5194/essd-9-47-2017.

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Abstract. Glacier mass balance measurements help to provide an understanding of the behavior of glaciers and their response to local and regional climate. In 2005 the United States Geological Survey established a surface mass balance monitoring program on Sperry Glacier, Montana, USA. This project is the first quantitative study of mass changes of a glacier in the US northern Rocky Mountains and continues to the present. The following paper describes the methods used during the first 11 years of measurements and reports the associated results. From 2005 to 2015, Sperry Glacier had a cumulative mean mass balance loss of 4.37 m w.e. (water equivalent). The mean winter, summer, and annual glacier-wide mass balances were 2.92, −3.41, and −0.40 m w.e. yr−1 respectively. We derive these cumulative and mean results from an expansive data set of snow depth, snow density, and ablation measurements taken at selected points on the glacier. These data allow for the determination of mass balance point values and a time series of seasonal and annual glacier-wide mass balances for all 11 measurement years. We also provide measurements of glacier extent and accumulation areas for select years. All data have been submitted to the World Glacier Monitoring Service and are available at doi:10.5904/wgms-fog-2016-08. This foundational work provides valuable insight about Sperry Glacier and supplies additional data to the worldwide record of glaciers measured using the glaciological method. Future research will focus on the processes that control accumulation and ablation patterns across the glacier. Also we plan to examine the uncertainties related to our methods and eventually quantify a more robust estimate of error associated with our results.

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Butler, David R. "Classics and archives." Progress in Physical Geography: Earth and Environment 40, no. 5 (October 2016): 732–37. http://dx.doi.org/10.1177/0309133316671098.

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In 1925, then-Captain AW Stevens of the US Army Air Corps took low-angle, oblique aerial photographs of the spectacular landscape of Glacier National Park, Montana (USA). Two of those photographs, of astonishing clarity, were used in a US Geological Survey Professional Paper published in 1959, but were subsequently assigned to the US National Archives and never utilized again. This paper advocates the usefulness of Stevens’ photographs for documenting landscape change from the early 20th century to the present. Stevens’ photographs illustrate the “state” of numerous Park glaciers in 1925, and are the first known aerial photographs of the Park glaciers. These photographs can be used in comparison to modern photographs to illustrate the extent of glacial recession that has occurred in the Park since 1925.

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Murray, Donald R., and William W. Locke. "Dynamics of the Late Pleistocene Big Timber Glacier, Crazy Mountains, Montana, U.S.A." Journal of Glaciology 35, no. 120 (1989): 183–90. http://dx.doi.org/10.3189/s0022143000004470.

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Abstract The late Pleistocene Big Timber glacier of west-central Montana was used as the test case for a model which calculates the mass balance of a paleoglacier using glacial flow theory. Application of Glen’s flow law to a detailed reconstruction of the glacier provided an estimate of the component of mass flux due to internal deformation. Assuming basal slip to be zero where mass flux due to deformation was a maximum, the mass flux at the equilibrium-line altitude (ELA) an ablation gradient of 3.0 ± 0.6 mm/m, and an accumulation gradient of 1.0 ± 0.2 mm/m were determined. Application of the continuity model above and below the ELA generated a second estimate of mass flux at discrete points along the glacier. The difference between deformation flux and continuity flux yields a first approximation of slip, which is highly variable along the glacier. Since the mass-balance gradients are climatically controlled, this model provides information on the paleoclimatic setting of the glacier. The low gradients indicate that, during the last glacial maximum, the east side of the central Rocky Mountains experienced a cold, dry environment much like that of modern-day glaciers in the Brooks Range of Alaska.

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Murray, Donald R. "Late Pleistocene Glacier Dynamics and Paleoclimate Of South-Western Montana and North-Eastern Idaho. U.S.A." Annals of Glaciology 14 (1990): 350. http://dx.doi.org/10.1017/s0260305500009216.

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Reliable reconstructions of paleoglaciers using topographic maps and aerial photographs allow calculation of effective basal shear stresses along the longitudinal profiles of these glaciers. Glacial flow theory applied to these shear stresses provides an estimate of the component of mass flux due to internal deformation. Assuming basal slip to be zero at the point where deformation mass flux is a maximum, minimum average accumulation gradients (above the equilibrium-line altitude (ELA)) and ablation gradients (below the ELA) can be calculated and minimum mass flux at the ELA can be estimated using the continuity equation. Average net winter accumulation can also be calculated by dividing the mass flux at the ELA by the accumulation area. Because local climate controls the mass balance of a glacier, and therefore the accumulation and ablation gradients, this model provides information on the climatic setting of these paleoglaciers. This model also allows estimation of basal slip as a factor in point estimates of glacial flow. Application of the continuity model above and below the ELA generates additional estimates of mass flux at discrete points along the glacier. The difference between deformation mass flux and continuity flux at these points yields a first approximation of basal slip, which is highly variable along the glacier. The model was tested on the Big Timber glacier of west-central Montana and applied to several other late Pleistocene glaciers in the northern Rocky Mountains of south-western Montana and north-eastern Idaho. Low ablation gradients (<4.0 mm m-1) suggest a climate during the late Pleistocene comparable to the present-day climate of the Brooks Range in Alaska. Calculated average net winter accumulation for the area is well below modern values, again indicating that the climate was much drier during the full glacial period. Basal sliding accounts for most (>90%) of the glacial flow near the terminus of each glacier but is variable along the rest of the glacier. While the mass-balance values are minima, they are assumed to be reasonable approximations of the actual values unless very high basal slip rates occurred along the entire length of each glacier.

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Murray, Donald R. "Late Pleistocene Glacier Dynamics and Paleoclimate Of South-Western Montana and North-Eastern Idaho. U.S.A." Annals of Glaciology 14 (1990): 350. http://dx.doi.org/10.3189/s0260305500009216.

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Reliable reconstructions of paleoglaciers using topographic maps and aerial photographs allow calculation of effective basal shear stresses along the longitudinal profiles of these glaciers. Glacial flow theory applied to these shear stresses provides an estimate of the component of mass flux due to internal deformation. Assuming basal slip to be zero at the point where deformation mass flux is a maximum, minimum average accumulation gradients (above the equilibrium-line altitude (ELA)) and ablation gradients (below the ELA) can be calculated and minimum mass flux at the ELA can be estimated using the continuity equation. Average net winter accumulation can also be calculated by dividing the mass flux at the ELA by the accumulation area. Because local climate controls the mass balance of a glacier, and therefore the accumulation and ablation gradients, this model provides information on the climatic setting of these paleoglaciers.This model also allows estimation of basal slip as a factor in point estimates of glacial flow. Application of the continuity model above and below the ELA generates additional estimates of mass flux at discrete points along the glacier. The difference between deformation mass flux and continuity flux at these points yields a first approximation of basal slip, which is highly variable along the glacier.The model was tested on the Big Timber glacier of west-central Montana and applied to several other late Pleistocene glaciers in the northern Rocky Mountains of south-western Montana and north-eastern Idaho. Low ablation gradients (<4.0 mm m-1) suggest a climate during the late Pleistocene comparable to the present-day climate of the Brooks Range in Alaska. Calculated average net winter accumulation for the area is well below modern values, again indicating that the climate was much drier during the full glacial period. Basal sliding accounts for most (>90%) of the glacial flow near the terminus of each glacier but is variable along the rest of the glacier. While the mass-balance values are minima, they are assumed to be reasonable approximations of the actual values unless very high basal slip rates occurred along the entire length of each glacier.

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Barth, Aaron M., Elizabeth G. Ceperley, Claire Vavrus, Shaun A. Marcott, Jeremy D. Shakun, and Marc W. Caffee. "¹⁰Be age control of glaciation in the Beartooth Mountains, USA, from the latest Pleistocene through the Holocene." Geochronology 4, no. 2 (December 16, 2022): 731–43. http://dx.doi.org/10.5194/gchron-4-731-2022.

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Abstract. Alpine glaciers in the western United States are often associated with late Holocene Little Ice Age (LIA) advances. Yet, recent studies have shown many of these glacial landforms are remnants of latest Pleistocene retreat with only the most cirque-proximal moraines preserving LIA activity. Additionally, the timing and magnitude of glacial advances during the Neoglacial–LIA interval remains uncertain, with presumed maximum extents occurring during the LIA driven by lower Northern Hemisphere insolation levels. Here we present 10Be surface exposure ages from a glacial valley in the Beartooth Mountains of Montana and Wyoming, United States. These new data constrain the presence of the glacier within 2–3 km of the cirque headwalls by the end of the Pleistocene with implications for large-scale retreat after the Last Glacial Maximum. Cirque moraines from two glaciers within the valley preserve a late Holocene readvance, with one reaching its maximum prior to 2.1±0.2 ka and the other 0.2±0.1 ka. Age variability among the moraines demonstrates that not all glaciers were at their largest during the LIA and presents the possibility of regional climate dynamics controlling glacial mass balance.

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Karlstrom, Eric T. "EVIDENCE FOR COALESCENCE OF LAURENTIDE AND ROCKY MOUNTAIN GLACIERS EAST OF GLACIER NATIONAL PARK, MONTANA." Physical Geography 20, no. 3 (May 1999): 225–39. http://dx.doi.org/10.1080/02723646.1999.10642677.

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Locke, William W. "Late Pleistocene Glaciers and the Climate of Western Montana, U.S.A." Arctic and Alpine Research 22, no. 1 (February 1990): 1. http://dx.doi.org/10.2307/1551716.

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Seligman, Zachary M., Anna E. Klene, and Frederick E. Nelson. "Rock glaciers of the Beartooth and northern Absaroka ranges, Montana, USA." Permafrost and Periglacial Processes 30, no. 4 (September 16, 2019): 249–59. http://dx.doi.org/10.1002/ppp.2019.

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Beget, James E. "Modeling the Influence of Till Rheology on the Flow and Profile of the Lake Michigan Lobe, Southern Laurentide Ice Sheet, U.S.A." Journal of Glaciology 32, no. 111 (1986): 235–41. http://dx.doi.org/10.1017/s0022143000015562.

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AbstractThe late Wisconsin Shelbyville till was deposited in southern Illinoisc. 20 000–21 000 year B.P. and records the maximum southern advance of the Lake Michigan lobe of the Laurentide ice sheet. The yield strength calculated for a representative till debris flow found just south of the ice margin is 8 kPa (0.08 bar), and probably approximates yield strength of basal Shelbyville till. An ice-profile model assuming plastic behavior in basal till suggests the southern Lake Michigan lobe may have been unusually thin. Reconstructed Laurentide glacier profiles from the south-west and western Great Plains (South Dakota, Alberta, Minnesota, and Montana), and the MacKenzie Delta, N.W.T., are similar to those inferred for the southern Great Lakes area, and much thinner than those of most modern ice sheets. The Pleistocene Laurentide ice sheet may have been asymmetric: thicker in the east than in the west. Glaciers resting on weak sediments can move both by subglacial sediment deformation (creep) and sliding at the sediment–ice interface. Till rheology is complex; shearing of till by over-riding glaciers would increase porosity and further reduce yield strength.

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Beget, James E. "Modeling the Influence of Till Rheology on the Flow and Profile of the Lake Michigan Lobe, Southern Laurentide Ice Sheet, U.S.A." Journal of Glaciology 32, no. 111 (1986): 235–41. http://dx.doi.org/10.3189/s0022143000015562.

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AbstractThe late Wisconsin Shelbyville till was deposited in southern Illinois c. 20 000–21 000 year B.P. and records the maximum southern advance of the Lake Michigan lobe of the Laurentide ice sheet. The yield strength calculated for a representative till debris flow found just south of the ice margin is 8 kPa (0.08 bar), and probably approximates yield strength of basal Shelbyville till. An ice-profile model assuming plastic behavior in basal till suggests the southern Lake Michigan lobe may have been unusually thin. Reconstructed Laurentide glacier profiles from the south-west and western Great Plains (South Dakota, Alberta, Minnesota, and Montana), and the MacKenzie Delta, N.W.T., are similar to those inferred for the southern Great Lakes area, and much thinner than those of most modern ice sheets. The Pleistocene Laurentide ice sheet may have been asymmetric: thicker in the east than in the west. Glaciers resting on weak sediments can move both by subglacial sediment deformation (creep) and sliding at the sediment–ice interface. Till rheology is complex; shearing of till by over-riding glaciers would increase porosity and further reduce yield strength.

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Osborn, Gerald. "Holocene tephrostratigraphy and glacial fluctuations in Waterton Lakes and Glacier national parks, Alberta and Montana." Canadian Journal of Earth Sciences 22, no. 7 (July 1, 1985): 1093–101. http://dx.doi.org/10.1139/e85-111.

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Waterton Lakes National Park in Alberta and Glacier National Park in Montana lie along adjacent sections of the continental divide in the Rocky Mountains. In cirques or near divides there is evidence for two ages of glacial deposits. Younger deposits are generally well preserved, poorly vegetated, and bear no tephra and no or very small lichens. Older deposits are more poorly preserved, better vegetated, bear Rhizocarpon sp. lichens at least up to 92 mm in diameter, and bear tephra. The tephra often occurs in two different coloured horizons, but both are compositionally equivalent to Mazama tephra.The older advance has a minimum age of about 6800 14C years BP and a probable maximum age of about 12 000 14C years BP. It is correlated with the pre-Mazama Crowfoot Advance of the Canadian Rockies. Deposits of the younger advance are probably not too much older than mid-19th century, because some glaciers began retreating from the deposits about then. The younger advance is correlated to the Cavell Advance of the Canadian Rockies and the Gannett Peak Advance of the American Rockies.Both advances were minor. The older advance left moraines about 1.5 km or less beyond present glacier margins and depressed ELA's an average of 40 m below modern values.

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Sturchio, Neil C., Kenneth L. Pierce, Michael T. Murrell, and Michael L. Sorey. "Uranium-Series Ages of Travertines and Timing of the Last Glaciation in the Northern Yellowstone Area, Wyoming-Montana." Quaternary Research 41, no. 3 (May 1994): 265–77. http://dx.doi.org/10.1006/qres.1994.1030.

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AbstractUranium-series age determinations by mass spectrometric methods were done for travertines and associated carbonate veins related to clastic deposits of the last glaciation (Pinedale) in the northern Yellowstone area. Dramatic variations in the hydrologic head are inferred from variations in the elevation of travertine deposition with time and are consistent with the expected hydrologic effects of glaciation. We determine the following chronology of the Pinedale Glaciation, with the key assumption that travertine deposits (and associated carbonate veins) perched high above present thermal springs were deposited when glaciers filled the valley below these perched deposits: (1) the early Pinedale outlet glacier advanced well downvalley between 47,000 and 34,000 yr B.P.; (2) the outlet glacier receded to an interstadial position between 34,000 and 30,000 yr B.P.; (3) an extensive Pinedale ice advance occurred between 30,000 and 22,500 yr B.P.; (4) a major recession occurred between 22,500 and 19,500 yr B.P.; (5) a minor readvance (Deckard Flats) culminated after 19,500 yr B.P.; and (6) recession from the Deckard Flats position was completed before 15,500 yr B.P. This chronology is consistent with the general trend of climatic changes in the northern hemisphere as revealed by recent high-resolution ice-core records from the Greenland ice sheet.

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Carrara, Paul E., and Deborah A. Trimble. "A Glacier Peak and Mount Saint Helens J volcanic ash couplet and the timing of deglaciation in the Colville Valley area, Washington." Canadian Journal of Earth Sciences 29, no. 11 (November 1, 1992): 2397–405. http://dx.doi.org/10.1139/e92-187.

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A Late Pleistocene volcanic ash couplet consisting of a Glacier Peak ash layer and an underlying Mount Saint Helens J ash layer has been identified at three sites in the Colville Valley area of northeastern Washington. This ash couplet has been reported as far east as northwestern Montana and therefore appears to have widespread distribution south of the International Boundary. Because areas covered by the Cordilleran Ice Sheet, as well as by local mountain glaciers and icefields, were undergoing extensive deglaciation when these ash layers were deposited, about 11 200 BP, the ash couplet is an important time-stratigraphic marker, and its identification at a site provides information about the extent of deglaciation at that time.The ash couplet is easily recognized in the study area. Distinguishing characteristics include (i) the medium-sand-size (0.2–0.4 mm) rounded glass fragments and abundant mafic crystals in the fine-sand fraction of the Glacier Peak ash, a white layer 5–10 mm thick; (ii) the fine sandy silt and mafic-crystal-poor Mount Saint Helens J ash, also a white layer 5–10 mm thick, below the Glacier Peak ash; and (iii) the stratigraphic position of the couplet beneath the much younger Mazama ash.The presence of the Glacier Peak and Mount Saint Helens J ash couplet in the Colville Valley, about 50 km north (upglacier) from the Late Wisconsin terminal moraine near the town of Springdale, indicates that the active margin of the Colville sublobe of the Cordilleran Ice Sheet had retreated at least that distance by 11 200 BP.

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Turchetti, Benedetta, Ciro Sannino, Ambra Mezzasoma, Laura Zucconi, Silvano Onofri, and Pietro Buzzini. "Mrakia stelviica sp. nov. and Mrakia montana sp. nov., two novel basidiomycetous yeast species isolated from cold environments." International Journal of Systematic and Evolutionary Microbiology 70, no. 8 (August 1, 2020): 4704–13. http://dx.doi.org/10.1099/ijsem.0.004336.

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Five yeast strains were isolated from soil and sediments collected from Alps and Apennines glaciers during sampling campaigns carried out in summer 2007 and 2017, respectively. Based on morphological and physiological tests and on phylogenetic analyses reconstructed with ITS and D1/D2 sequences, the five strains were considered to belong to two related but hitherto unknown species within the genus Mrakia, in an intermediate position between Mrakia cryoconiti and Mrakia arctica. The names Mrakia stelviica (holotype DBVPG 10734T) and Mrakia montana (holotype DBVPG 10736T) are proposed for the two novel species and a detailed description of their morphological, physiological and phylogenetic features are presented. Both species fermented glucose, sucrose and trehalose, which is an uncommon feature in basidiomycetous yeasts, and showed septate hyphae with teliospore formation.

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Lyman, R. Lee. "Paleoecological implications of the first prehistoric record of water vole (Microtus richardsoni) from Washington state, USA." Quaternary Research 92, no. 2 (April 29, 2019): 381–87. http://dx.doi.org/10.1017/qua.2019.15.

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AbstractRemains of the North American water vole (Microtus richardsoni) have previously been recovered from late Pleistocene and Holocene deposits in southwestern Alberta, western Montana, and north-central Wyoming. All are within the historically documented modern range of the metapopulation occupying the Rocky Mountains; no ancient remains of this large microtine have previously been reported from the metapopulation occupying the Cascade Range. Four lower first molar specimens from the late Holocene Stemilt Creek Village archaeological site in central Washington here identified as water vole are from the eastern slope of the Cascade Range and are extralimital to the metapopulation found in those mountains. There is no taphonomic evidence indicating long-distance transport of the teeth, and modern trapping records suggest the local absence of water voles from the site area today is not a function of sampling error. The precise age of the Stemilt Creek Village water voles is obscure but climate change producing well-documented late Holocene advances of nearby alpine glaciers could have created habitat conditions conducive to the apparent modest shift in the range of the species represented by the remains.

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Christiansen, E. A., and E. Karl Sauer. "Stratigraphy and structure of Pleistocene collapse in the Regina Low, Saskatchewan, Canada." Canadian Journal of Earth Sciences 39, no. 9 (September 1, 2002): 1411–23. http://dx.doi.org/10.1139/e02-038.

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The Regina Low is a collapse structure, formed as a result of dissolution of salt from the Middle Devonian Prairie Evaporite Formation. In this study, collapse has affected the Upper Cretaceous Pierre Shale and the Ardkenneth and Snakebite members of the Bearpaw Formation of the Montana Group; the Mennon, Dundurn, and Warman formations of the Sutherland Group; and the Floral and Battleford formations of the Saskatoon Group. A structural closure of 125175 m approximates the thickness of the Middle Devonian Prairie Evaporite Formation. In the Early Pleistocene, about 54 m of collapse took place in eastern Regina accounting for the preservation of Snakebite Member. Major collapses of about 58 and 86 m took place in northern Regina during deposition of Middle Pleistocene, pre-Illinoian Dundurn Formation. The final major collapse of about 127 m took place in northeastern Regina between deposition of the lower and upper tills of the Floral Formation. Eighty-seven metres of this collapse took place during deposition of the Late Pleistocene, interglacial, Sangamon Pasqua Member of the Floral Formation. The Pleistocene fill in the Regina Low collapse structure suggests that collapse took place when dissolution of salt from the Prairie Evaporite Formation was accelerated by high hydraulic gradients created by the surcharge pressures of the glaciers.

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Marti, Renaud, Simon Gascoin, Thomas Houet, Dominique Laffly, and Pierre René. "Evaluation du modèle numérique d'élévation d'un petit glacier de montagne généré à partir d'images stéréoscopiques Pléiades : cas du glacier d'Ossoue, Pyrénées françaises." Revue Française de Photogrammétrie et de Télédétection, no. 208 (September 5, 2014): 57–62. http://dx.doi.org/10.52638/rfpt.2014.107.

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Les bilans de masse des glaciers de montagne constituent des indicateurs climatiques régionaux reconnus. Moyennant une hypothèse sur la densité de la surface glaciaire, on peut établir le bilan de masse d'un glacier par différence entre deux modèles numériques d'élévation (MNE) successifs. L'obtention de MNEs précis à haute résolution est donc un enjeu important en glaciologie. Un couple d'images stéréoscopiques Pléiades acquis en septembre 2013 a été traité afin de générer un MNE du glacier d'Ossoue (Hautes Pyrénées) à 2m de résolution en planimétrie et 1m en altimétrie. Un levé DGPS sur le glacier et sa périphérie à une date proche a permis d'estimer l'erreur altitudinale du MNE Pléiades à ±1.8m. Ce résultat permet d'envisager une utilisation opérationnelle des images stéréoscopiques Pléiades pour déterminer des bilans de masses précis de glaciers de montagne, y compris dans les zones impraticables pour les mesures de terrain.

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Butler, David R., George P. Malanson, and David M. Cairns. "Stability of alpine treeline in Glacier National Park, Montana, U.S.A." Phytocoenologia 22, no. 4 (December 5, 1994): 485–500. http://dx.doi.org/10.1127/phyto/22/1994/485.

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Duk-Rodkin, Alejandra, and Owen L. Hughes. "Pleistocene Montane Glaciations in the Mackenzie Mountains, Northwest Territories." Géographie physique et Quaternaire 46, no. 1 (November 23, 2007): 69–83. http://dx.doi.org/10.7202/032889ar.

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ABSTRACT During the Pleistocene the Mackenzie Mountains were affected by a series of glaciations. Through all the glaciations a single pattern seems to have been repeated: a Cordilleran ice sheet formed to the west of the continental divide and montane valley glaciers formed to the east. The montane glaciers in the Mackenzie Mountains emanated from two differents sources: a) a glacial divide, lying generally along the topographic divide between Pacific and Arctic drainage, and dividing the westerly flowing Cordilleran Ice Sheet from easterly and northerly flowing montane glaciers, b) local peaks in the Canyon Ranges. There were two well defined glacial advances in this mountain region: lllinoian, Late Wisconsinan, and one or more less defined pre-lllinoian glaciation(s). lllinoian and Late Wisconsinan glaciations are herein named Mountain River and Gayna River glaciations respectively. These advances are usually identifiable in valleys by frontal and segments of lateral moraines and glacial erosional features. Pre-lllinoian glaciation(s) have been recognized so far only in stratigraphie sections. The older advances were more extensive than the Gayna River advance; associated deposits occur higher on the valley sides and further down the valley than those associated with Gayna River Glaciation. During Mountain River Glaciation some of the montane glaciers in the Canyon Ranges merged to form piedmont glaciers. In contrast, during Gayna River Glaciation, the local glaciers consisted of single tongues, and these were mostly restricted to tributary valleys that had northward facing cirques.

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Cancer-Pomar, Luis, José Antonio Cuchí, Fernando Lampre-Vitaller, Javier Del Valle-Melendo, and Gonzalo Fernández-Jarne. "Observations glaciologiques (1998–2015) sur le glacier d'Infierno (Pyrénées, Espagne)." La Houille Blanche, no. 1 (February 2020): 84–91. http://dx.doi.org/10.1051/lhb/2019060.

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D'une surface de 7,6 ha et une altitude comprise entre 2700 et 2950 m, le glacier d'Infierno est situé dans les Pyrénées aragonaises. Il est localisé dans l'unique chaîne de montagne espagnole qui conserve des glaciers blancs. Nous présentons les données glaciologiques du glacier de la période 1998–2015 en relation avec les facteurs météorologiques : températures, précipitations et rythmes d'accumulation nivale. Ce glacier a un comportement très variable, avec des fréquents rythmes opposés entre des années successives. Ainsi, les années de plus grand recul sont 2006, 2012 et 2015. Et, bien au contraire, dans les années 2013 et 2014 la couverture neigeuse a largement dépassé les limites du glacier. L'étude de l'accumulation nivale montre que les précipitations neigeuses printanières tardives peuvent favoriser le bilan. Elles peuvent même dépasser l'importance de celles des mois d'hiver, grâce à l'effet protecteur qu'elles exercent sur la surface de glace durant la période la plus chaude. Le glacier est sensible au réchauffement global, mais dans le haut bassin du Gállego, nous observons une faible augmentation de l'accumulation de neige tout au long des années écoulées du XXIe siècle, malgré une forte variabilité interannuelle.

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Duk-Rodkin, Alejandra, and Owen L. Hughes. "Age Relationships of Laurentide and Montane Glaciations, Mackenzie Mountains, Northwest Territories." Géographie physique et Quaternaire 45, no. 1 (December 13, 2007): 79–90. http://dx.doi.org/10.7202/032847ar.

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ABSTRACT The Mackenzie Mountains were glaciated repeatedly by large valley glaciers that emanated from the Backbone Ranges, and by much smaller valley glaciers that emanated from peaks in the Canyon Ranges. During the Late Wisconsinan the Laurentide Ice Sheet reached its all-time maximum position. The ice sheet pressed against the Canyon Ranges and moved up major valleys causing the diversion of mountain waters and organizing a complex meltwater system that drained across mountain interfluve areas towards the northwest. Two ages of moraines deposited by montane glaciers occur widely in the Mackenzie Mountains. Near the mountain front certain of the older moraines have been truncated by the Laurentide Ice Sheet, and others have been incised by meltwater streams emanating from the Laurentide ice margin, indicating that these older moraines predate the maximum Laurentide advance. Locally, certain of the younger montane moraines breach moraines and other ice marginal features of the Laurentide maximum, indicating that the younger montane glaciation post-dated the Laurentide maximum. Some large montane glaciers extended out from the mountains to merge with the retreating Laurentide Ice Sheet. There are several localities that display the age relationships between montane and Laurentide glaciations such as Dark Rock Creek, Durkan-Lukas Valley, Little Bear River and Katherine Creek. The older of the local montane glaciations is correlated tentatively with Reid Glaciation (lllinoian?) of central Yukon, and the younger with the Late Wisconsinan McConnell Glaciation. The Laurentide Glaciation is correlated with Hungry Creek Glaciation of Bonnet Plume Depression, which probably culminated about 30,000 years ago or somewhat later.

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30

DeBolt, Ann, and Bruce McCune. "Lichens of Glacier National Park, Montana." Bryologist 96, no. 2 (1993): 192. http://dx.doi.org/10.2307/3243801.

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31

Hughes, O. L., C. Tarnocai, and C. E. Schweger. "Pleistocene stratigraphy, paleopedology, and paleoecology of a multiple till sequence exposed on the Little Bear River, Western District of Mackenzie, N.W.T., Canada." Canadian Journal of Earth Sciences 30, no. 4 (April 1, 1993): 851–66. http://dx.doi.org/10.1139/e93-071.

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The Little Bear River section lies in a transition zone between Mackenzie Lowland and Canyon Ranges of Mackenzie Mountains. Within the transition zone, the maximum extent of the Laurentide ice sheet overlaps the former extent of montane glaciers that emanated from the higher parts of Canyon Ranges or from the still higher Backbone Ranges to the southwest. Five montane tills, each with a paleosol developed in its upper part, indicate five separate glaciations during each of which a valley glacier emanating from the headwaters of Little Bear River extended eastward into the transition zone. The uppermost of the montane tills is overlain by boulder gravel containing rocks of Canadian Shield origin deposited by the Laurentide ice sheet.Solum and B horizon depths, red colours, and lack of leaching and cryoturbation indicate that although each successive interglacial interval was cooler than the preceding one, even the last of the intervals was warmer than the Holocene. Climatic conditions during one of the intervals inferred from the paleobotanic data, particularly spruce forest development, are consistent with conditions inferred from the associated paleosol.The uppermost of the montane tills is thought to correlate with till of Reid (Illinoian) age in central Yukon. The paleosol developed on that till is, accordingly, thought to correlate with the Diversion Creek paleosol developed on drift of Reid age. The Laurentide boulder gravel is assigned to a stade of Hungry Creek Glaciation of Late Wisconsinan age. The Laurentide ice sheet reached its apparent all-time western limit during the Hungry Creek Glaciation maximum.

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32

Nielsen, Lewis T. "The Mosquitoes Of Glacier National Park, Montana." Journal of the American Mosquito Control Association 25, no. 3 (September 2009): 246–47. http://dx.doi.org/10.2987/09-5753.1.

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33

Butler, David R. "GLACIAL HAZARDS IN GLACIER NATIONAL PARK, MONTANA." Physical Geography 10, no. 1 (January 1989): 53–71. http://dx.doi.org/10.1080/02723646.1989.10642367.

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Clark, Adam M., Joel T. Harper, and Daniel B. Fagre. "Glacier-Derived August Runoff in Northwest Montana." Arctic, Antarctic, and Alpine Research 47, no. 1 (February 2015): 1–16. http://dx.doi.org/10.1657/aaar0014-033.

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35

Férnandez Navarro, Hans. "Glaciares del semiárido chileno en el contexto de cambio climático y explotación minera." Espacios 7, no. 13 (December 15, 2017): 17. http://dx.doi.org/10.25074/07197209.13.690.

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El contexto de cambio climático y presión sobre recursos hídricos que reviste la agricultura, la expansión urbana y las actividades extractivas como la minería, han situado en la discusión pública la importancia de los glaciares como reservorios de agua y piezas fundamentales del equilibrio ecosistémicos y social de los territorios. La zona semiárida de Chile ha estado relacionada a continuos episodios de sequía y aumento de temperaturas mínimas, lo que ha incidido en el retroceso de glaciares, principal fuente de agua para la región. Agravando el problema, se ha detectado que la minería a gran escala ha eliminado volumen glaciar en zonas de alta montaña. A pesar de lo anterior, en el país aún no se construye un cuerpo normativo que proteja a los glaciares frente a intervenciones de origen antrópico. Los intentos legislativos de construir un marco legal que proteja a los glaciares no han llegado a buenos resultados.Palabras claves: glaciares, semiárido, legislación, recurso hídrico, sustentabilidad.

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36

Ruiz-Fernández, Jesús, Cristina García-Hernández, and Antonio Fernández-Fernández. "Organización altitudinal de las formas kársticas del Macizo Occidental de los Picos de Europa (Montañas Cantábricas) y su interrelación con el glaciarismo cuaternario y la morfodinámica periglaciar." Cadernos do Laboratorio Xeolóxico de Laxe. Revista de Xeoloxía Galega e do Hercínico Peninsular 41 (December 2, 2019): 153–200. http://dx.doi.org/10.17979/cadlaxe.2019.41.0.5822.

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En los conjuntos montañosos con un desarrollo altitudinal importante, la tipología de las formas kársticas presentes, así como la intensidad de la disolución kárstica, varían en función de la altitud (además de los consabidos factores estructurales). Sin embargo, apenas existen estudios relativos a esta cuestión. Este trabajo, basado fundamentalmente en la realización de un trabajo de campo sistemático y exhaustivo que se ha prolongado durante varios años en el Macizo Occidental de los Picos de Europa, se centra en el estudio del modelado kárstico de este macizo cantábrico de alta montaña. En él se han identificado los procesos y formas presentes, determinando las interrelaciones del relieve kárstico con el glaciarismo cuaternario y con la morfodinámica periglaciar, estableciendo tres fases de evolución kárstica en función de la sucesión de distintas condiciones morfoclimáticas y de la consiguiente actuación de diversos agentes morfogenéticos (karst preglaciar, glaciar y postglaciar) y definiendo cuatro franjas kársticas a tenor del gradiente altitudinal: área de karst cubierto oceánico de media montaña, sector de los frentes glaciares y las cubetas glaciokársticas bajas, desierto kárstico, y área de karst nival de alta montaña.

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37

Greyes, Natch. "Climate change is eliminating Pinguicula macroceras Link habitat in Montana." Carnivorous Plant Newsletter 43, no. 2 (June 1, 2014): 59–60. http://dx.doi.org/10.55360/cpn432.ng341.

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The damage caused by climate change to plant communities is often obscured by a confluence of causes and vague deadlines, but in Montana there is an exception to that trend. The National Park Service in Montana has been leading efforts to document glacial melting. In the process, they have incidentally recorded ongoing damage to the handful of colonies of Pinguicula macroceras Link that occur in Glacier National Park.

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Alva Huayaney, Miguel Ernesto, and Juan Felipe Melendez de la Cruz. "Aplicacion de la Teledeteccion para el analisis multitemporal de la regresion glaciar en la Cordillera Blanca." Investigaciones Sociales 13, no. 22 (June 11, 2014): 71–83. http://dx.doi.org/10.15381/is.v13i22.7216.

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Los cambios climáticos que se vienen sucediendo en nuestro planeta, nos permiten tener un acercamiento a lo que está ocurriendo en los glaciares de montaña de nuestro país, que se caracterizan por su fragilidad. La Cordillera Blanca constituye una de las más importantes áreas glaciares en nuestro país. La mayor parte de monitoreos se han realizado con trabajos de campo, donde muchas veces se presentan una serie de obstáculos para la colección de datos; de esta manera la Geomática mediante la Teledetección nos permite realizar monitoreos con mayor facilidad, mediante el empleo de imágenes satelitales para determinar el área de deshielo de los glaciares. Para el presente estudio se ha tomado como referencia los límites políticos de los distritos de Huaraz e Independencia, así como el empleo de distintas imágenes de satélite de los años 1989, 1998 y 2005, lo que nos permite analizar el comportamiento de la regresión glaciar en un período de 16 años y predecir dicho comportamiento para 25 años (2014).

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39

Gigot, Jessica. "Enormous Glacier Calvings Montage." Ecotone 17, no. 2 (2021): 116. http://dx.doi.org/10.1353/ect.2021.0038.

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40

Waller, John S. "Status of Fishers in Glacier National Park, Montana." Northwestern Naturalist 99, no. 1 (March 2018): 1–8. http://dx.doi.org/10.1898/nwn17-07.1.

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Kendall, Katherine C., Jeffrey B. Stetz, David A. Roon, Lisette P. Waits, John B. Boulanger, and David Paetkau. "Grizzly Bear Density in Glacier National Park, Montana." Journal of Wildlife Management 72, no. 8 (November 2008): 1693–705. http://dx.doi.org/10.2193/2008-007.

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42

Stetz, Jeff B., Katherine C. Kendall, and Amy C. Macleod. "Black bear density in Glacier National Park, Montana." Wildlife Society Bulletin 38, no. 1 (November 8, 2013): 60–70. http://dx.doi.org/10.1002/wsb.356.

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43

Soto Bäuerle, María Victoria, Francisco Ferrando Acuña, and Rosemary Vieira. "Características geomorfológicas de un sistema de glaciares rocosos y de su sustenatción en Chile semiárido." Investigaciones Geográficas, no. 36 (January 1, 2002): 1. http://dx.doi.org/10.5354/0719-5370.2002.27741.

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Se estudia un sistema de glaciares rocosos en un valle alto andini del semiárido de Chile, en la cuenca del Río Limarí , con el propósito de identificar las distintas formas presentes, su dinámica, las relaciones con el entorno y los diferentes estadios evolutivos. Se reconoce formas glaciales y periglaciales, en las que se inscriben algunas de las fases evolutivas de los glaciares rocosos. De estos últimos, las tipologías reconocidas corresponden a un glaciar rocoso inactivo con forma de lengua, y a glaciares rocosos de talud simples, ondulados y lobulados. Se establece que los procesos periglaciales de las vertientes son un factor muy importante en la dinámica actual de los sistemas de glaciares rocosos en función del constante aporte de detritos. El conjunto de formas analizadas está morfogeneticamente ligado tanto a procesos glaciales en su origen como a periglaciales en su evokución, dando cuenta de un sistema de complejo que constituye un continuum geomorfológico. El grado de actividad del sistema denota una marcada estacionalidad, debido al breve y poco riguroso período invernal y al prolongado y temperado período estival de la alta montaña de los Andes de la región semiárida chilena.

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Titos Martínez, Manuel. "La expedición del naturalista alsaciano Guillaume Philippe Schimper a Sierra Nevada en 1847 / The expedition of the Alsatian naturalist Guillaume-Philippe Schimper to Sierra Nevada in 1847." Ería 2, no. 2 (October 10, 2019): 207–21. http://dx.doi.org/10.17811/er.2.2019.207-221.

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En 1847 los alsacianos Daniel Dollfus-Ausset y Guillaume-Philippe Schimper realizaron una expedición a Sierra Nevada, en el sur de España. Su objetivo era la búsqueda de una nueva especie de cabra montes, pero su interés se extendía a la geografía, el paisaje, el glaciarismo y la botánica. En aquella expedición se realizó la primera fotografía al daguerrotipo que se conoce de Sierra Nevada, y se encontraron restos de antiguos glaciares cuaternarios sobre los que elaboraron una teoría mantenida como válida durante bastante tiempo. En este artículo se describe la personalidad de los viajeros, las circunstancias de su viaje y lo que representa el mismo en la historia científica de Sierra Nevada.En 1847, les Alsaciens Daniel Dollfus-Ausset et Guillaume-Philippe Schimper firent une expédition en Sierra Nevada,dans le sud de l’Espagne. Son but était de rechercher une nouvelle espèce de chèvre de montagne, mais son intérêt s’est étendu à la géographie, au paysage, au glacierisme et à la botanique. Au cours de cette expédition, une photographie au daguerréotype de Sierra Nevada a été prise pour la première fois. De même, des restes d’anciens glaciers du Quaternaireont été identifiés, et sur ceux-ci, ils ont développé une théorie maintenue comme valable pendant un certain temps. Cet article décrit la personnalité des voyageurs, les circonstances de leur voyage et ce que cette expérience représente dans l’histoire scientifique de la Sierra Nevada.In 1847 the Alsatians Daniel Dollfus-Ausset and Guillaume-Philippe Schimper made an expedition to Sierra Nevada, insouthern Spain. His goal was to search for a new species of mountain goat, but his interest extended to geography, landscape, glacierism and botany. In that expedition, the first daguerreotype photograph of Sierra Nevada was taken, and remains of ancient Quaternary glaciers were identified (on which they developed a theory maintained as valid for quite some time). This article explains the personality of the travelers,the circumstances of their trip and what it represents in the scientific history of Sierra Nevada.

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Carrara, Paul E. "A 12 000 year radiocarbon date of deglaciation from the Continental Divide of northwestern Montana." Canadian Journal of Earth Sciences 32, no. 9 (September 1, 1995): 1303–7. http://dx.doi.org/10.1139/e95-106.

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During the Pinedale (Late Wisconsinan) glaciation, an outlet glacier from a mountain ice field flowed eastward across the Continental Divide through Marias Pass in northwestern Montana. This outlet glacier was the major source of the Two Medicine glacier, a large piedmont glacier that extended from the mountain front east about 55 km onto the plains. An accelerator mass spectrometry radiocarbon age of 12 194 ± 145 BP (AA-9530) was obtained from a wood fragment, underlying a Glacier Peak tephra and a Mount Saint Helens set J tephra in a section of lake sediments, near Marias Pass. This radiocarbon age provides a minimum date of deglaciation for the Marias Pass area that is about 800 years older than a previous estimate. Furthermore, the radiocarbon age indicates that the Two Medicine glacier was no longer being supplied by its major source and if it still existed was only as a dying, stagnant ice mass.

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Butler, David R., Jack G. Oelfke, and Lori A. Oelfke. "Historic Rockfall Avalanches, Northeastern Glacier National Park, Montana, U.S.A." Mountain Research and Development 6, no. 3 (August 1986): 261. http://dx.doi.org/10.2307/3673396.

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Munroe, Jeffrey. "Holocene Glacier Fluctuations in Glacier National Park, Montana, USA, Reconstructed from Lacustrine Sedimentary Records." Quaternary International 279-280 (November 2012): 343. http://dx.doi.org/10.1016/j.quaint.2012.08.1009.

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48

Foit Jr., Franklin F., Peter J. Mehringer Jr., and John C. Sheppard. "Age, distribution, and stratigraphy of Glacier Peak tephra in eastern Washington and western Montana, United States." Canadian Journal of Earth Sciences 30, no. 3 (March 1, 1993): 535–52. http://dx.doi.org/10.1139/e93-042.

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Tephra layers from Williams Lake Fen, Wildcat Lake, and East Wenatchee, Washington, and Kearns Basin, Lost Trail Pass, Sheep Mountain Bog, and Marys Frog Pond, Montana, were analyzed by electron microprobe (EMP), and associated lake deposits were radiocarbon dated. Though the tephra layers can be grouped by source (Glacier Peak, Mount Mazama, Mount Saint Helens, and unknown source), statistical analyses of both glass and mineral compositions show that finer distinctions within a group (for example, Glacier Peak B, M, and G) cannot be made on the basis of chemical data obtained using conventional EMP techniques. It appears that more-sensitive analytical techniques may be needed to discriminate among the Glacier Peak tephras. Tephra stratigraphy at the various sites reveals a potentially greater complexity in Glacier Peak tephra distributions and ages than was anticipated. All sites, except Sheep Mountain Bog and East Wenatchee, contained two Glacier Peak tephras. Taken as a whole the Glacier Peak tephra layers may record closely timed, multiple eruptions with restricted ash falls as well as widespread tephra from large eruptions. Radiocarbon dating generally confirms a 14C age of 11 200 years BP for a distal Glacier Peak couplet(s) that occurs, stratigraphically, both above and below Mount Saint Helens J tephra in east-central Washington.

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Heideman, Marit, Brian Menounos, and John J. Clague. "A multi-century estimate of suspended sediment yield from Lillooet Lake, southern Coast Mountains, Canada." Canadian Journal of Earth Sciences 55, no. 1 (January 2018): 18–32. http://dx.doi.org/10.1139/cjes-2017-0025.

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We use annually laminated lake sediments to estimate suspended sediment yield for a 3850 km2 montane catchment in the British Columbia Coast Mountains. Sediment yield over the past 369 years averages 213 ± 38 Mg·km−2·a−1. Sediment yield increases to 285 ± 50 Mg·km−2·a−1 during the first half of the twentieth century and declines thereafter. The frequency of high-yield events during the 369 year period is irregular: 11 of the 34 events occur in the early part of the twentieth century, a time when glaciers in the watershed underwent major retreat. We fitted a generalized extreme value (GEV) model to estimate quantiles of the sediment yield distribution, and we used epoch analysis to examine persistence in sediment yield following 34 of the largest events. Persistence is greatest for the most extreme events; it is more variable for events that recur, on average, every 10–25 years. Our results indicate that sediment yield is linked to long-term changes in sediment supply to the lake. The results of this study extend earlier sediment yield estimates and improve understanding of linkages to watershed geomorphology, recent glacier retreat, and landslides in the Lillooet River watershed.

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Meentemeyer, Ross K., and David R. Butler. "HYDROGEOMORPHIC EFFECTS OF BEAVER DAMS IN GLACIER NATIONAL PARK, MONTANA." Physical Geography 20, no. 5 (September 1999): 436–46. http://dx.doi.org/10.1080/02723646.1999.10642688.

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Journal articles on the topic 'Glaciers – Montana'

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