Ice-cored Rock Glaciers Research Articles

Surface Elevation Variations on Lachman II Debris-covered Glacier (Ice-cored Rock Glacier), James Ross Island, Antarctic Peninsula, and Its Responses to Recent Climate Change

Surface Elevation Variations on Lachman II Debris-covered Glacier (Ice-cored Rock Glacier), James Ross Island, Antarctic Peninsula, and Its Responses to Recent Climate Change

The Acidalia Mensa region on Mars: A key element to test the Mars ocean hypothesis

We present the results of a detailed photogeological study of a region surrounding Acidalia Mensa (43–50°N, 15–35°W) based on analysis of a mosaic of the CTX images (nominal resolution ~5 m/px). The main result of the study is the unfolding of the geologic history of the study region and determination of absolute model ages of its major episodes. The documented history begins with the formation of a volcanic plateau of Acidalia Mensa ~4 Ga ago. The surface of the Acidalia plateau was strongly modified since its formation. The crater size-frequency distribution (CSFD) on the plateau indicates that the resurfacing was likely consisted of multiple episodes. The latest such episode recognizable by the crater statistics occurred ~3.65 Ga ago. The vast majority of the surface around Acidalia Mensa is covered by materials of the background plains that correspond to the interior unit of the Vastitas Borealis Formation (VBF). The CSFD on the background plains corresponds to an absolute model age (AMA) of ~3.58 Ga, which is completely within the range of AMAs determined for the VBF along its boundary with the southern uplands. Small-scale features such as bright cones/mounds, polygonal troughs, and flow-like mantling materials postdate the emplacement of the background plains and manifest the post-formational evolution of the VBF. The majority of crater ejecta in the study area have higher albedo in the CTX and HiRISE images, but appear as dark spots in the THEMIS-IR nighttime images. These wavelength-dependent properties of the ejecta indicate the presence of light-toned and fine-grained material beneath the surface of the background plains. This material was the source of numerous bright cones/mounds. We interpret the formation of this reservoir as the result of sorting of large amounts of water/mud deposited in the study area and, by implication, within the northern lowlands. The final episodes of the ancient geologic history of the study area were related to the emplacement of materials of the thick flows at topographically high levels within the Acidalia plateau ~3.47 Ga ago. The morphology of the flows is inconsistent with lava and we interpret the occurrences of the thick flows as the result of displacement of water-saturated regolith in the form of either soli- or gelifluction flows, or ice-cored rock glaciers.

Rock glacier characteristics serve as an indirect record of multiple alpine glacier advances in Taylor Valley, Antarctica

Abstract. The geomorphic record indicates that alpine glaciers in the McMurdo Dry Valleys of southern Victoria Land, Antarctica, appear to advance during interglacial periods in response to ice-free conditions in the Ross Sea. Few records of these advances are preserved and/or subaerially exposed, complicating the interpretations of regional glacier response to climate changes. Here, we present geophysical and geochemical analyses of a rock glacier that originates from icefalls fed by alpine Doran Glacier in central Taylor Valley. The rock glacier exhibits a trend of increased weathering of granitic clasts via ventifaction and grussification down-flow. Meltwater ponds on the rock glacier exhibit variable salinity that ranges from freshwater to higher than seawater, with the highest salinity pond near the rock glacier toe. Ground-penetrating radar analyses reveal the feature to possess a primarily clean ice interior, with layers of englacial debris. Stable isotopic data from three ice cores support a glacial origin for the ice within the rock glacier. These data suggest that the current morphology of the rock glacier is the result of multiple events of increased ice contribution caused by advances of Doran Glacier, which is the main source of ice to the rock glacier. We therefore demonstrate the potential of ice-cored rock glaciers to record multiple advances and retreats of Dry Valley glaciers, permitting the interpretation of glacial responses to Pleistocene and Holocene climate change even where direct records are not present.

Recession of glaciers in the Suntar-Khayata Mountains and methodological consideration of its assessment

This study of glacial-cryogenic complexes of Suntar-Khayata Range is a logical continuation of the research started by M.M. Koreysha in 1957–1959. The studied key site is situated in the upstream of the Burgaly River on the northern slope of Mus-Khaya Mountain (2959 m a.s.l.). It includes glaciers № 29–31 and their ice-cored moraines of different ages. Our study is based on field geomorphologic mapping carried out in 2012, as well as on geospatial analysis of multi-temporal high resolution (1–0.6 m) aerial and satellite imagery. The modern terminus elevation of 16 investigated glaciers varies from 2090 to 2350 m a.s.l. It was found that glaciers’ terminal positions have risen on average from 2052±102 to 2226±114 m a.s.l. after 1945 aerial photography. The termini of Glacier № 29 and Glacier № 31 have retreated approximately by 500–650 m, while the ELA has risen by 61±38 m, from 2346±56 to 2407±55 m a.s.l. The total glaciated area has reduced in size by approximately 36%. The surface of Glacier № 31 has lowered by 50–70 m in its terminal part due to ablation. The estimated glacier shrinkage is valid only for the exposed ice area, since the large amount of glacier ice is buried in ablation moraines, glacier-derived rock glaciers and other glacial-cryogenic landforms. Some ice-cored rock glaciers are 30 to 80 m in thickness. A surface ice flow velocity has decreased 5–6 times compared to the 1957–1959 values. A 45-m-deep geothermal borehole drilled in the middle of Glacier № 31 in 1958–1959 has completely melted away and its mouth shifted 150 m down the glacier surface. The drilling equipment of 1958 is now on the top of a steep 70-m-high rock wall which was entirely covered with ice before 1958. This obviously reflects the magnitude of glacier shrinkage.

Recent evolution and degradation of the bent Jatunraju glacier (Cordillera Blanca, Peru)

This article brings new insight into the recent evolution and degradation of the bent Jatunraju glacier in the northern part of the Cordillera Blanca, Peru. Analysis of topographical maps, aerial photos and satellite images covering a period of 66years and a field survey performed in June 2013 and May 2014 helped to describe the geomorphological setting and ongoing processes. Recent evolution and degradation processes are also deduced from surface movements. Historical geodetic measurements (1967–1968; 1977–1984) and current LANDSAT images (2001–2013) were used to estimate surface velocities and changes in surface velocities over time. Our investigation showed that the most significant changes happened at an altitude of between 4300 and 4450m asl. A significant decrease in surface velocities and increase in debris thickness indicate that this part of Jatunraju turned from a debris-covered glacier into an ice-cored rock glacier during the analyzed period. Particular parts of the article describe the cycle of formation and extinction of supraglacial lakes and the melting of buried (debris-covered) ice. A scenario of future evolution is outlined and discussed as well. We assume that ice degradation within the debris-covered glacier will continue and that the altitude of its presence will increase hand-in-hand with the changing environment.

Debris-covered Glaciers During Glacial and Interglacial Periods on the Taurus Mountains (Turkey)

The debris-covered glaciers are observed all over the glaciation regions of the world (Alps, Antarctica, Greenland, Andes, Cascades, Rocky Mountains and etc.). The debris covered glaciers are known as the formations which occur in the retreating phase of glaciers and sometimes they are confused with rock glaciers. In this study, hypothesis that debris covered glaciers existed in glaciation fields with similar conditions during the previous glacial periods in Pleistocene is questioning. The experiences which are acquired from actual glaciers in Taurus range and the researches that have been done in the other glaciated valleys of the world shows apparent evidence that there were debris-covered glaciers in the past glacial periods and also debris layer can be found during the advancing phase of a glacier. From the valleys that are occupied with debris-covered glaciers the following conclusions have been extended. When they have compared to past bare glaciers, past debris-covered glaciers a) responded later to warm air and temperature rise, b) advanced to lower altitudes, c) experienced different sediment transport and deposit from bare glaciers, d) didn’t experienced ablation from the surface of the glacier slowly, but faster ablation due to collapsing and calving of subglacial-englacial channels, e) maintained themselves as fully covered dead ice/glaciers in protected cirque areas in the last stage of glaciation. If the retreating of the glacier continues until it is completely covered by the debris layer, than it may become an ice-cored rock glacier.

Mass movement in northeast Afghanistan

Mass movements of nearly all types occur in Afghanistan but in the high relief, rugged Pamir and Hindu Kush mountains of northeastern Afghanistan, mass-movement threats to lives and property necessitated study to elucidate problems to development. Twenty-two different mass movements in bedrock in the Badakhshan Province of northeastern Afghanistan were studied for this paper, including large rock falls and rock slides, along with massive slope-failure complexes with many types and rates of movement. Where higher altitudes prevail in the region, ice-cemented and ice-cored rock glaciers are also common and overlie some of the other mass movements. Inasmuch as seismic energy sources in the Eastern Hindu Kush are maximal in southern Badakhshan, and relief, slope angles and precipitation all increase from west to east as well, the causes of the pervasive mass movement are plentiful enough, although direct cause and slope-failure effect are not known. Some weak sedimentary lithologies downfaulted into, or draped across crystalline rocks, also failed. Some intermixed tills also occur but are not easily differentiated, even with analysis on the ground. Using high resolution satellite imagery and digital elevation models, we assessed geomorphologic parameters to characterize spatial-organization structures related to zones of erosion, deposition and further hazard potential. Analyses indicate that many of the massive slope failures can be characterized and differentiated into various process domains and chronologic-development zones with their different impacts upon the landscape. Mass movements in Afghanistan can exhibit unique topographic signatures that can be used to better assess hazards in other mountain areas, especially where landslide-dam breakout floods threaten. Development of roads, bridges, buildings, and irrigation networks should be done with care in these regions of Afghanistan.

Soil processes and development rates in the quartermain mountains, upper taylor glacier region, antarctica

.Soil‐forming processes and soil development rates are compared and contrasted on glacial deposits in two adjacent and coeval valleys of the Quartermain Mountains, which are important because they display Miocene glacial Stratigraphy and some of the oldest landforms in the McMurdo Dry Valleys. More than 100 soil profiles were examined on seven drift sheets ranging from 115 000 to greater than 11.3 million years in age in Beacon Valley and Arena Valley. Although the two valleys contain drifts of similar age, they differ markedly in ice content of the substrate. Whereas Arena Valley generally has ‘dry‐frozen’ permafrost in the upper 1 m and minimal patterned ground, Beacon Valley contains massive ice buried by glacial drift and ice cored rock glaciers and has ice‐cemented perma‐frost in the upper 1 m and considerable associated patterned ground. Arena Valley soils have twice the rate of profile salt accumulation than Beacon Valley soils, because of lower available soil water and minimal cryoturbation. The following soil properties increase with age in both valleys: weathering stage, morphogenetic salt stage, thickness of the salt pan, the quantity of profile salts, electrical conductivity of the horizon of maximum salt enrichment, and depth of staining. Whereas soils less than 200 000 years and older soils derived from sandstone‐rich ground moraine are Typic Anhyorthels and Anhyturbels, soils of early Quaternary and older age, particularly on dolerite‐rich drifts, are Petronitric Anhyorthels. Arena Valley has the highest pedodiversity recorded in the McMurdo Dry Valleys. The soils of the Quartermain Mountains are the only soils in the McMurdo Dry Valleys known to contain abundant nitrates.

Origin of rock glaciers: Observations from Mellemfjord, Disko Island, Central West Greenland

Surface and interior characteristics of a tongue-shaped rock glacier at Mellemfjord on Disko Island are described. A long natural section shows the existence of a solid ice core. The implications for the origin of ice within the rock glacier and its surface debris layer are discussed and, from this, the rock glacier age is estimated at about 550 years; that is, it was probably initiated during the initial period of the Little Ice Age. It is suggested that the climatic control on ice-cored rock glaciers in particular is more pronounced than traditionally assumed. It is suggested that although the geomorphological feature described displays many characteristics of a normal glacier, it should be classified as a true rock glacier. © 1996 John Wiley & Sons, Ltd.

Debris-Covered Glaciers in the Sierra Nevada, California, and Their Implications for Snowline Reconstructions

Ice-walled melt ponds on the surfaces of active valley-floor rock glaciers and Matthes (Little Ice Age) moraines in the southern Sierra Nevada indicate that most of these landforms consist of glacier ice under thin ( ca. 1 - 10 m) but continuous covers of rock-fall-generated debris. These debris blankets effectively insulate the underlying ice and greatly reduce rates of ablation relative to that of uncovered ice. Such insulation explains the observations that ice-cored rock glaciers in the Sierra, actually debris-covered glaciers, are apparently less sensitive to climatic warming and commonly advance to lower altitudes than do adjacent bare-ice glaciers. Accumulation-area ratios and toe-to-headwall-altitude ratios used to estimate equilibrium-line altitudes (ELAs) of former glaciers may therefore yield incorrect results for cirque glaciers subject to abundant rockfall. Inadvertent lumping of deposits from former debris-covered and bare-ice glaciers partially explains an apparently anomalous regional ELA gradient reported for the pre-Matthes Recess Peak Neoglacial advance. Distinguishing such deposits may be important to studies that rely on paleo-ELA estimates. Moreover, Matthes and Recess Peak ELA gradients along the crest evidently depend strongly on local orographic effects rather than latitudinal climatic trends, indicating that simple linear projections and regional climatic interpretations of ELA gradients of small glaciers may be unreliable.

Glacier ice-cored rock glaciers in the Yukon Territory, Canada?

Glacier ice-cored rock glaciers in the Yukon Territory, Canada?

A glacier icecored rock glacier, Tröllaskagi, Iceland

A glacier icecored rock glacier, Tröllaskagi, Iceland

Preliminary Observations on Two Rock Glaciers in South Georgia, Falkland Islands Dependencies

AbstractTwo rock glaciers are described from the maritime sub-Antarctic island of South Georgia. The Cooper Sound rock glacier is a spatulate feature, probably ice-cored, 1.5 km long, and developed below a dissected cirque headwall. The Binary Peaks rock glacier is a lobate feature, possibly ice-cemented, only 175 m long, and contiguous with the talus behind it. Evidence for an ice-cored rock glacier in this maritime environment indicates that the debris supply and receiving glacier areas may be more important factors in determining rock-glacier development than zonal climate.

Preliminary Observations on Two Rock Glaciers in South Georgia, Falkland Islands Dependencies

AbstractTwo rock glaciers are described from the maritime sub-Antarctic island of South Georgia. The Cooper Sound rock glacier is a spatulate feature, probably ice-cored, 1.5 km long, and developed below a dissected cirque headwall. The Binary Peaks rock glacier is a lobate feature, possibly ice-cemented, only 175 m long, and contiguous with the talus behind it. Evidence for an ice-cored rock glacier in this maritime environment indicates that the debris supply and receiving glacier areas may be more important factors in determining rock-glacier development than zonal climate.

Movement of an Ice-Cored Rock Glacier, Tungsten, N.W.T., Canada, 1963-1980

In August 1963 Dr. H. Gabrielse, of the Geological Survey of Canada, established five lines of marked boulders on what is now believed to be a large ice-cored rock glacier near Tungsten, Northwest Territories. The boulders were aligned with survey targets located on the rock walls of the valley in which the rock glacier is located. The distances from the snout of the rock glacier to eight forest trees along its perimeter were measured and blazed into the trees. In July 1980, we visited the rock glacier and resurveyed the marked boulders and the rock glacier's snout in order to establish the rate and nature of movement of the rock glacier over the past 17 years.

Wenkchemna Glacier: ablation complex and rock glacier in the Canadian Rocky Mountains

The characteristics and behavior of the Wenkchemna Glacier in the Valley of the Ten Peaks of the Canadian Rocky Mountains are described. Early descriptions, old photographs, tree-rings, an annual sequence of photos since 1965, and field observations provide a data base. The Wenkchemna Glacier combines characteristics of ice-cored rock glaciers, ablation complexes, and glaciers, supporting the concept of a transition between these features. It is the product of a unique geomorphic–climatic system where a large mountain wall of northerly exposure produces a glacial micro–climate, a freeze–thaw weathering environment, a high rockfall frequency, and copious avalanche activity that led, in turn, to a thin, active mass of glacier ice that is preserved by a cover of rock debris. The behavior of the Wenkchemna Glacier has lagged behind that of surrounding glaciers by at least 70 years. Stagnation and differential ablation are the primary processes of glacier wastage. The landforms produced by the Wenkchemna Glacier include rock glacier features, such as arcuate ridges of debris, as well as hummocky ablation moraines typical of glacier stagnation.

Rock Glaciers and Block fields, Review and new data

Tongue-shaped and lobate rock glaciers are recognized in most alpine regions today. For the tongue-shaped, two situations emerge: those with buried glacier ice (debris-covered glaciers) called ice-cored rock glaciers, and those with interstitial ice known as ice-cemented rock glaciers. Those with ice cores are revealed by depressions between rock glacier and headwall cliff (where a former glacier melted), longitudinal marginal and central meandering furrows, and collapse pits. Ice-cemented rock glaciers ordinarily do not possess these features. As applied to 18 rock glaciers in the Colorado Front Range, 11 of 12 east of the Continental Divide are ice-cored, 6 west of the Divide are ice-cemented. The majority of lobate rock glaciers in the Colorado Front Range are on the south sides of valleys, and, except for talus, are the most voluminous form of mass wasting. All those active and above treeline have characteristics common to all rock glaciers. In addition, they originate from talus, contain interstitial ice, move outward from valley walls at 1–6 cm/yr, and transport more debris as a process of erosion than heretofore realized. Block fields and block slopes, in polar and alpine regions, are thin accumulations of angular to subrounded blocks, on bedrock, weathered rock, or transported debris. They extend along slopes parallel to the contour. Block streams are similar but extend downslope normal to the contour and into valleys. They are made of interlocked blocks without interstitial detritus, but many have finer material deeper inside. The fabric of surface blocks indicates that motion most likely occurred during a periglacial time when interstitial debris, now washed or piped out, permitted movement of the whole deposit.

Ice-Cored Rock Glacier, Galena Creek, Northern Absaroka Mountains, Wyoming

Galena Creek rock glacier (44°38930″ N., 109°47930″ W., elevation 2,680 to 3,110 m, length 1.6 km) originates in a north-facing cirque. Although this rock glacier morphologically resembles others described elsewhere, its upvalley two-thirds is composed of a continuous layer of debris 1 to 1.5 m thick over relatively clean glacier ice and has a maximum measured surface velocity of 80 cm/yr. The downvalley one-third is mantled by 2 to 3 m of debris (measured by seismic refraction) over ice of unknown debris content; it has a maximum measured velocity of 14 cm/yr. The transition zone between these two regions has several large (6-m-high, 90-m-wide) lobes that override one another at a maximum measured velocity of 6 cm/yr. Accumulation occurs primarily as wind-drifted snow in a narrow lens-shaped area against the cirque headwall. Most of the coarse debris is not incorporated in the ice, but is carried past the steep (13° to 33°) snow accumulation area beneath the cirque headwall by snow avalanche and rockfall to form the debris mantle. The debris mantle is sorted, with coarse fragments dominant at the surface and a zone of fines just above the debris-ice contact. The ice beneath the debris mantle contains a maximum of 10 to 12 percent debris by volume, except in probable longitudinal septa downglacier from large debris concentrations in the source area. Intersecting ridges and furrows on the up-valley portion of the rock glacier probably differ in age, according to lichen sizes and ridge sharpness, and are probably formed by compression below steep reaches of the glacier and by collapse into crevasses. Ice-cored rock glaciers uniquely have a very low ratio of accumulation area to ablation area (1:7 in this case). This is mainly the result of an ablation rate beneath the debris mantle that is estimated to be about two orders of magnitude less than that of clean ice. The slow rate of addition of ice makes the glacier thin and thus slow-moving. Because of the debris cover, rock glaciers are not nearly so sensitive to climate as are clean glaciers. The lag effect between retreat of clean glaciers and deactivation of rock glaciers may be several thousand years, and therefore mountain glacier moraines should be correlated with rock glaciers only with extreme care.