Glacier Formation Research Articles

Comprehensive assessment of rock glaciers in the Himachal Himalayas: Updated inventory and labelling

Rock glaciers are geomorphological features often used as a visible expression of mountain permafrost. These are creeping ice-debris with distinct ridge and furrow structures on the surface with a steep frontal slope. Rock glaciers, being the valuable past permafrost indicators, also have utmost hydrological significance in near future. Therefore, mapping of rock glaciers is an important step in order to understand permafrost regimes better. The Himalayas have large occurrences of these features and this study in Himachal Himalayas complied 789 rock glaciers, covering an area of about 336.2 km2. Different labels based on genesis, location, shape, form, surface relief and activity revealed rock glaciers were mainly derived from talus slopes (239) and exhibited tongue shape (377), primarily found in cirques (531). Most of them were classified as simple units (603) with well-developed surface relief (387), and they were found to be predominantly intact (760). The topographical parameters suggest majority of the rock glaciers are located between 4000 and 4800 m with mean elevation to be 4635 m. These rock glaciers are present at gentle to steep slope gradient (0 to 45°) with curvature ranging between −3.5 and 4.5, and majority showing convex curvature. The slope aspect conducive for formation of rock glaciers in Himachal is northerly (N, NW, NE). Principal geology for these rock glaciers belongs to slate, phyllite, quartzarenite, limestone and meta basics. The climatic parameters and indices also affect the rock glaciers occurrence significantly. The mean land surface temperature (LST) for majority rock glaciers lies between 0 and −15°C. While, the mean NDSI of all the rock glaciers varies from 0.04 to 0.68 and mean NDVI varies from −0.06 to 0.08. Overall, the inventory along with labels is a valuable database for understanding the distribution and characteristics of rock glaciers in the Himachal Himalayas.

Simulation of a former ice field with Parallel Ice Sheet Model – Snežnik study case

Abstract. In this paper, we present a reconstruction of climate conditions during the Last Glacial Maximum on a karst plateau Snežnik, which lies in Dinaric Mountains (southern Slovenia) and bears evidence of glaciation. The reconstruction merges geomorphological ice limits, classified as either clear or unclear, and a computer modelling approach based on the Parallel Ice Sheet Model (PISM). Based on extensive numerical experiments where we studied the agreements between simulated and geomorphological ice extent, we propose using a combination of a high-resolution precipitation model that accounts for orographic precipitation combined with a simple elevation-based temperature model. The geomorphological ice extent can be simulated with climate to be around 6 °C colder than the modern day and with a lower-than-modern-day amount of precipitation, which matches other state-of-the art climate reconstructions for the era. The results indicate that an orographic precipitation model is essential for the accurate simulation of the study area, with moist southern winds from the nearby Adriatic Sea having a predominant effect on the precipitation patterns. Finally, this study shows that transforming climate conditions towards wetter and warmer or drier and colder does not significantly change the conditions for glacier formation.

Was there a low-altitude Younger Dryas Stadial glacier in south-east Wales? Re-interpretation of landforms and palaeo-climatic inferences

A glacial origin for cirque-like hollows cut into the western escarpment of the Usk valley near Abergavenny, South Wales has become widely accepted. Associated supposed extensive moraine ‘festoons’ have been depicted merging and contemporaneous with Last Glacial Maximum (LGM) deposits formed by ice occupying the adjacent Usk valley. We re-interpret these festoons as the product mainly of rock slope failures (RSFs) emanating from the hollows. A cirque glacier origin is preferred to account for a compact double-ridge feature in one of the hollows. The equilibrium-line altitude (ELA) of the reconstructed glacier (357 m) is >60 m lower than all similarly small, presumed Younger Dryas Stadial (YDS; c., 12.9–11.7 ka) glaciers elsewhere in South Wales. To test whether this glacier nevertheless might date from the YDS, we apply three approaches to reconstruct annual palaeo-precipitation amounts at the ELA, two based on relationships between accumulation and ablation for modern glaciers and the third on a simple degree-day model (DDM) using likely climatic characteristics for this event. The DDM can be tailored to represent the recognised large-amplitude YDS annual temperature range rather than the much smaller one experienced by modern glaciers, making it our preferred approach. Although conditions along the Usk valley escarpment during the LGM would have been well suited to cirque glacier formation, the DDM approach, using the large-amplitude annual temperature ranges, suggests that a YDS age might also be possible. The results have implications for re-assessing the likely ages of some former small glaciers in South Wales.

Preliminary Investigation of the Remnants of Low-Latitude Glacial Activity on the Southeastern Margin of the Qinghai–Tibet Plateau

The formation of Quaternary glaciers represented a pivotal event in the climatic and geological history of the Tibetan Plateau. However, due to the scarcity of direct evidence for low-latitude glaciation, the timing and extent of late Quaternary glaciation on the Tibetan Plateau remain controversial. This study focuses on the Liangwang Mountains, which are located in the southeastern part of the Tibetan Plateau and has a maximum elevation of 2820 m, as the subject of investigation. Through a comprehensive application of glacial landform analysis, scanning electron microscopy (SEM)-based micromorphology analysis of quartz sand, and spore-pollen data analysis, we uncovered evident signs of glacial activity in this region during the Quaternary period. Our research identified typical glacial landforms such as cirques, U-shaped valleys, fluted moraines, and terminal moraines. Additionally, spore-pollen analysis revealed a high frequency of fir pollen, indicating cold climatic conditions during that time. Furthermore, the micromorphology analysis of quartz sand further corroborated the glacial origin of these deposits. Based on these combined findings, our study confirms that the Liangwang Mountains experienced glaciation during the Quaternary period, making them glacial relics at the lowest latitude currently known in mainland China. This discovery provides a valuable reference for understanding the paleoclimate and glacial history of the Tibetan Plateau and its surrounding regions.

Cirques in the Transantarctic Mountains reveal controls on glacier formation and landscape evolution

In this study, we analyse the morphometry of cirques in the Transantarctic Mountains (TAM) to understand regional glacier formation and landscape evolution since the onset of Cenozoic glaciations. We find that, unlike most glacierised regions worldwide, aspect bias for cirques in the TAM is not particularly strong, indicating that glaciers were able to form and cirques develop on slopes with a variety of aspects. This is perhaps unsurprising, given that Antarctica's climate has been conducive to long-lived and extensive glaciation for many millions of years. Surprisingly, where cirques in the TAM show an aspect bias, this is typically towards the North, NW and/or NE, rather than favouring South-facing slopes where direct solar radiation is comparatively limited. This lack of a poleward aspect bias is unlike most cirque populations globally and indicates that total solar insolation was not a key control on where former glaciers in the TAM were able to initiate. Instead, we argue that prevailing wind directions played a dominant role in controlling the slopes on which past glacier development was favoured. Specifically, South-facing slopes in the TAM are directly exposed to katabatic winds which originate from the interior of the East Antarctic Ice Sheet (EAIS). These slopes are therefore susceptible to wind deflation, with snow and ice being redistributed to lee-side slopes where it can accumulate due to protection from the wind. For this reason, North, NE and/or NW facing slopes may have favoured glacier development, and therefore resulted in a concentration of cirques with these aspects. This evidence suggests that most cirques in the TAM are no older 34 Ma, as outward radiating winds from the continent's interior could only have prevailed when the EAIS was present (in some form). By contrast, the very highest (and likely oldest) cirques in the TAM have more varied aspects, indicating that they may have formed before katabatic winds came to dominate, and by extension, before widespread growth of the EAIS at 34 Ma, and could perhaps have formed as far back as 60 Ma. In general, we find that cirques in the TAM have similar dimensions to those in other regions globally, despite having been occupied by glacial ice for far longer. Thus, our findings support a growing body of evidence which suggests that cirque size and glacier occupation times are not directly coupled, though there is some evidence of spatial variability in cirque size which might relate to the differences in the dynamics of former glaciers.

Photogrammetric Monitoring of Rock Glacier Motion Using High-Resolution Cross-Platform Datasets: Formation Age Estimation and Modern Thinning Rates

The availability of remote sensing imagery at high spatiotemporal resolutions presents the opportunity to monitor the surface motion of rock glaciers, a key constraint for characterizing the dynamics of their evolution. In this paper, we investigate four North American rock glaciers by automatically measuring their horizontal surface displacement using photogrammetric data acquired with crewed and uncrewed aircraft along with orbital spacecraft over monitoring periods of up to eight years. We estimate vertical surface changes on these rock glaciers with photogrammetrically generated digital elevation models (DEM) and digitized topographic maps. Uncertainty analysis shows that the imagery with the highest resolution and most precise positioning have the best performance when used with the automated change detection algorithm. This investigation produces gridded velocity fields over the entire surface area of each study site, from which we estimate the age of rock glacier formation using along-flow velocity integration. Though the age estimates vary, the ice within the modern extent of these landforms began flowing between 3000 and 7000 years before present, postdating the last glacial maximum. Surface elevation change maps indicate present-day thinning at the lower latitude/higher elevation sites in Wyoming, while the higher latitude/lower elevation sites in Alaska exhibit relatively stable surface elevations.

Climate scenarios, groundwater models, and uncertainties in long-term safety

Abstract. Assessing future climate scenarios plays a fundamental role in evaluating the long-term safety of a repository for high-level radioactive waste (HAW). Over the assessment period of 1 million years, the repository is affected by various processes and developments that must be considered in the design of the repository. Predictions are complicated by the dynamics of the climate and are subject to uncertainties. The aim of this study is to evaluate uncertainties for various climate-induced processes that are relevant for the safety assessment of a repository for HAW. This research addresses fundamental questions concerning the impact of future cold stages on different regions of Germany, the differences between past and future cold stages, the transfer of future climate developments to stylized climate models, and the uncertainties resulting from these models. The study identifies the primary climate processes that could potentially affect the evolution of a HAW repository, including the formation of glaciers or ice sheets, the development of permafrost conditions, fluctuations in sea level, erosion, and isostatic adjustment. These processes can be represented in numerical groundwater models through parameter variations. In this project, these parameter variations and the impact of climatic states on different processes will be modeled for a sensitivity study. Finally, the results will be analyzed with respect to uncertainties, and possible improvements to dealing with uncertainties will be discussed. The focus of the presentation is on the climate impacts and the implementation in the model.

Geomorphological record of the glacial to periglacial transition from the Bølling–Allerød to the Holocene in the Central Pyrenees: the Lòcampo cirque in the regional context

In the highest tributaries of the Upper Garonne Basin, Central Pyrenees, cirques up to 2600 m a.s.l. were already deglaciated by 15–14 ka. The long‐term deglaciation during Termination‐1 (T‐1) was interrupted by glacial advances within the cirques during the Bølling–Allerød (B‐A) interstadial and the Younger Dryas stadial. The cirques preserve a variety of glacial and periglacial landforms whose chronologies are poorly known. This study is focused on the Lòcampo cirque (42°38′06″N and 0°59′10″E), Upper Garonne Basin, where a detailed geomorphological map and 10Be terrestrial cosmic ray exposure (CRE) dating allowed us to constrain the chrono‐sequence between the glacial and periglacial domains. In the small Lòcampo cirque, a glacier formed a cirque moraine between 2200 and 2300 m a.s.l., which surrounds a relict rock glacier encompassing several transversal ridges. Additionally, longitudinal ridges typically observed in debris‐covered glaciers are preserved between the moraine and the rock glacier. The eight‐sample data set of CRE ages indicates the formation of the cirque moraine during the second half of the B‐A, by 13.2±1.1 ka. Exposure ages from the rock glacier boulders show a range between 13.6±0.9 and 11.9±0.7 ka, which did not allow its formation to be chronologically constrained. Therefore, the environmental evolution following the moraine stabilization could follow the formation of a debris‐covered glacier at the bottom of the Lòcampo cirque, with the subsequent formation of the rock glacier. After the rock glacier formation, its front rapidly ceased at 13.6±0.9 ka, while the upper ridges gradually stabilized until it became definitively relict at 11.9±0.7 ka or afterwards. These results show evidence of the complex glacial to periglacial transition that needs more robust chronological data sets to better understand the role of climate forcing and local topography during the deglaciation in mid‐latitude mountain environments.

Forming Terrains by Glacial Erosion

We introduce the first solution for simulating the formation and evolution of glaciers, together with their attendant erosive effects, for periods covering the combination of glacial and inter-glacial cycles. Our efficient solution includes both a fast yet accurate deep learning-based estimation of highorder ice flows and a new, multi-scale advection scheme enabling us to account for the distinct time scales at which glaciers reach equilibrium compared to eroding the terrain. We combine the resulting glacial erosion model with finer-scale erosive phenomena to account for the transport of debris flowing from cliffs. This enables us to model the formation of terrain shapes not previously adequately modeled in Computer Graphics, ranging from U-shaped and hanging valleys to fjords and glacial lakes.

Glacier–rock glacier interactions in the eastern Hindu Kush, Nuristan, Afghanistan [35.92,71.13] in the period 1976–2019

ABSTRACT Landsystem relationships between glaciers and rock debris supply in a mountain landscape domain, (), are described. Decimal latitude-longitude [dLL] geolocations are used to identify features and transects in an information landscape. Geo-located features are coded, enabling transects between a 1976 expedition and 2019 Google Earth imagery to be compared. Rock debris is progressively added to 1-3 km long glaciers which become debris-covered. Cirque glaciers eventually assume rock glacier (RG) forms when supraglacial debris loads are high. Some rock glacier snouts reach main valley floors and still advance over meadows. This behaviour is attributed to high geomorphic activity producing rock detritus and transport to glaciers in the early Little Ice Age. The advances of rock glacier snouts are a consequence of thinning; low-angle glaciers still moving beneath debris-covered glaciers (GLd) covers. Persistent melt pools continue to develop within the surface debris cover of glaciers and rock glaciers and expose glacier ice. All the rock glaciers are below the regional snowline and permafrost can be discounted for rock glacier formation. Scree slope (SS) development may ultimately be sufficient to cover bare glacier ice moving from a glacier (GL) to debris-covered glacier (GLd) to rock glacier (RG). Reverse slopes in the debris at the foot of screes mark the mass continuum of glacier flow below the debris cover, not the ‘rooting zone’ of a permafrost-derived RG. Scree slopes themselves show no evidence of rock glacier-like flow. A simple glacier ice-debris transport continuum model is sufficient and necessary for rock glacier formation and flow.

10Be exposure ages and paleoenvironmental significance of rock glaciers in the Western Tatra Mts., Western Carpathians

Relict rock glaciers are well-preserved features of high-elevated valleys in the Western Tatra Mts., Western Carpathians, but their chronology remained poorly constrained with numerical dating methods. We present the first robust set of 10Be exposure ages for eight rock glaciers with front elevation of 1376–1819 m asl. The results suggest that the rock glaciers stabilized throughout the Weichselian Lateglacial from ∼16.5 ka to 11 ka. This timing is consistent with the period of rock glacier stabilization in European mountain regions, but it extends the age span previously determined for rock glaciers in the Tatra Mts. There are differences between north- and south-facing valleys in the elevation and time of the stabilization of the rock glaciers, which were probably caused by contrasts in potential incoming solar radiation that affected the retreat of former glaciers and the subsequent formation of the rock glaciers. The initiation altitude of ∼1610 and ∼1830 m asl determined for the oldest and youngest dated rock glaciers is generally consistent with previous estimates of the glacier equilibrium line altitude during the Greenland Stadials 2.1 and 1, respectively. However, the lower limit of the rock glaciers is well above regional paleopermafrost features from the same periods, which suggests that rock glaciers may underestimate past permafrost extents and temperature declines disputing their regional validity for paleoenvironmental reconstructions.

Anomalously light geological complex on the watershed plain of the Yano-Indigir lowland

The research method is a purposeful petrophysical interpretation of the gravitational field. The object under study appeared during prospecting geological and geophysical work as a hindrance to the solution of the main geological problem. Its density is 1 g/cm3, the height of the sole is 35 m, the area is 1420 km2, the volume is 20 km3. The object is defined as an abnormally light Ice Complex (ALIC). The revealed density is explained by peat-ice performance. In ALIC, a near-surface lenticular-layered formation ice has been uncovered, the structure of which indicates the generation of the mass of the complex ahead of sedimentation. The gravimetric data, the landscape and the details of the ALIC structure are interconnected and make up the first — the most complete view of the complex at the moment. The main elements of the presentation are the three phases of the development of the complex. The first is classical, generally accepted for polygonal—vein structures, the second differs from the classical one by the absence of frost-breaking cracking, the third is the growth of formation ice. The qualitative difference of the thermophysical components of the cryolithozone of the territory is given, which made it possible to introduce several concepts concerning the generation of peat-ice mass ALIC. Such as: heat dissipation capacity of the middle layer, stabilization of the zero isotherm at the petrophysical boundary; conditions for the beginning of the growth of lenticular-layered ice; accelerated lateral segregation growth of powerful ice veins; constancy of the thermal resistance of the cryolithozone. On the basis of these concepts, models of the development of the second and third phases of ALIC are compiled, and a view on the theory of the formation of cover glaciers is formed, which follows from the model of the third phase. The novelty of the research consists: in identifying a unique petrophysical object, in defining this object as ALIC, in identifying an ice massif on the territory of ALIC, in presenting the development of the complex as a sequence of three phases, in compiling models of the second and third phases of ALIC and in an original approach to the formation of cover glaciers.

NO PUBLICATION, NO FAME: REASSESSING ARNOLD GUYOT’S (1807–1884) PIONEERING CONTRIBUTIONS TO THE GLACIAL THEORY

ABSTRACT In the summer of 1838, Arnold Guyot was asked by Louis Agassiz to gather information on Alpine glaciers, with the aim of reporting their findings in September, at the annual gathering of the French Geological Society. Guyot’s observations of the internal structure of the ice and interpretations on glacier movements, reported orally at the conference, were new to science. Unfortunately, because of purported illness, Guyot did not send his manuscript to be published and missed his first opportunity to be recognized as a pioneer in glacier studies. During the years 1841 to 1847, Guyot published a series of notes, detailing results of his field work in tracing erratic blocks in the central Alpine region, in the Alpine foreland and in the Jura Mountains. The level of detail in his work was unprecedented and has not been replicated since. Recognizing that erratic blocks of similar lithology could be followed along organized paths of deposition, Guyot could invalidate those theories that sought to explain their deposition by chaotic means, such as floods, debacles or drifting icebergs loaded with rock debris. Only moraines, composed of material transported by glaciers, could explain the mapped arrangements of erratic blocks. Geological proofs for extensive glaciations in central Europe had just been found, and Guyot could demonstrate them on his hand-drawn map. But, in 1848, a revolution broke out in Neuchâtel. The local academy where Guyot was engaged as a professor shut down and all staff were left without pay. Answering a call from Agassiz who had emigrated to the USA in 1846, Guyot departed Switzerland and joined his friend there in the fall of 1848. In his luggage were all the papers on his unfinished project, including his map, and a full collection of erratic rock specimens. After arrival in the USA, Guyot had to begin a new professional life and could not devote significant attention to the subject of erratic blocks. In 1849, he showed his map of the erratic basins of Switzerland and discussed his results with various members of the American Association for the Advancement of Science (AAAS); he also shared his novel ideas about the climatic conditions required for the formation of large glaciers; however, he did not formally publish the results of his work in the Alps, and he thus lost his second opportunity for wider peer recognition and for driving the acceptance of the glacial theory. Only in 1874, 26 years after his arrival in the USA and a year after Agassiz’s death, did Guyot open his boxes of alpine rock specimens and display his unpublished map in the Museum of the College of New Jersey (later Princeton University), where he was engaged as a professor. In 1883, at age 77, his memory of the unpublished 1838 report on glaciers was still in his conscience which finally pushed him to submit it for printing at Neuchâtel. It passed largely unnoticed, however, and Guyot died one year later without recognition attached to his name for his original, innovative work. This paper reviews Guyot’s work and analyses his relationship with Agassiz while both were working in Neuchâtel. It seeks to evaluate his pioneering work on glaciers and on erratic blocks. It includes a copy of Guyot’s map of the erratic basins of Switzerland, kept to this day in the archives of Princeton University.

The extreme Anthropogen of the Arctic: the formation of the Great Glacier, the emergence a man and the Arctic Ocean in the Early Holocene

The relevance of the article stems from the need to consider recent events in the Arctic in recent time, which are largely contradictory. The aim of the study is to show extreme environmental changes in the Arctic of anthropogenic nature, including the emergence of man and the Arctic Ocean in the Early Holocene. The territory of the Arctic was a landmass with high mountains, in the period preceding the Holocene, on which a large glacier formed 30-18 thousand years ago (Late Pleistocene). The glacier slid irrepressibly southward over great distances, where it covered vast areas of Europe and North America. In the years that followed, a dramatic warming and active melting of the glacier began. By the beginning of the Holocene, the glacier had melted, and a narrow strait of the Atlantic appeared at the foot of Greenland. Coniferous-deciduous forests, numerous rivers and the first human settlements appeared on the flat territory of the Arctic, and various animals – mammoths, horses, bulls - spread out. However, a major catastrophic event occurred by the middle of the Holocene (6.0 thousand years ago), after active volcanism in the Arctic: the collapse of the central part of the Arctic to a depth of about 5 km and the formation of the Central Arctic graben, associated with the appearance of a huge amount of endogenous water. There began a rapid movement of water on the flat parts of the Arctic and the formation of the modern huge, shallow (50-100 m) shelf - the Arctic Ocean. Many human settlements were flooded, animals escaped, in part, on high uplands. For example, huge animal cemeteries were preserved on the Novosibirsk Islands. A new cooling of the climate occurred 4 thousand years ago, and an ice sheet formed on the surface of the ocean, which led to the name of the North Glacial Ocean in Russia. Modern man began to explore the coastal territories of the Arctic shelf since the mid - Holocene, but active industrial development of the Arctic began in the 21st century.

Rock glacier composition and structure from radio wave speed analysis with dipping reflector correction

AbstractWe assess the composition and geometry of four individual rock glaciers in Alaska, Wyoming and Colorado by measuring their radio wave speed and applying these results to ground-penetrating radar depth corrections and dielectric mixing models. Our method includes a correction for subsurface reflector dip angle, which we show can lead to an incorrect determination of wave speeds using common midpoint configurations. By observing the radar properties of the rock glaciers and their supraglacial debris, we find that some of the sites exhibit nearly pure ice cores, and all of the sites indicate volumetric ice fractions >50%. These results have implications for terrestrial glaciology and hydrology because the present ice volume is connected to past ice accumulation and subsurface ice preservation, which may affect the future availability of alpine water resources. An understanding of the processes that govern rock glacier evolution over a wide range of latitudes and elevations will also contribute to the exploration of planetary surfaces such as Mars, which hosts a significant population of debris-covered glaciers. Our subsurface composition and geometry estimates will inform simulations of rock glacier formation and evolution to test hypothesized ice origin mechanisms along with the preservation of climate signals.

A deep-sea foraminiferal assemblage scattered through the late Cenozoic of Antarctic Peninsula and its biostratigraphic and biogeographic implications

AbstractOur knowledge of the foraminiferal fossil record of Antarctica is notoriously patchy but still offers us an overview of its Cenozoic faunas. Few occurrences have been reported for the continent, with deep-sea assemblages described mainly for its eastern portion. Here we describe 21 taxa of large agglutinated foraminifers from the Miocene Hobbs Glacier Formation and the Plio-Pleistocene Weddell Sea Formation on Seymour Island, West Antarctica, including the gigantic Ammodiscus vastus new species. Most of them consist of genera or species typical of deep-sea agglutinated assemblages. All specimens are completely filled and partially covered by lithified micrite. This, along with the postfill fragmentation of some tests, indicates their re-elaboration from older deposits. Because all of these foraminifers share the same taphonomic features and most of them represent taxa associated with deep-sea settings, they probably represent a flysch-type assemblage from an unknown deposit that was eroded and had its microfossils scattered through post-Paleogene sediments. A Paleocene age for this putative assemblage is indicated by the presence of Reticulophragmiun garcilassoi (Frizzell, 1943), a Paleocene index fossil, and by its association with the Cretaceous–Paleocene Ammodiscus pennyi Cushman and Jarvis, 1928. If taken as a coherent foraminiferal assemblage, it represents one of the few deep-sea assemblages known for West Antarctica, and the first flysch-type assemblage recognized for the Antarctic Cenozoic. In addition, it would show that the Paleocene foraminiferal communities of the West Antarctica's deep-sea floor were more like their Pacific counterparts than their Atlantic equivalents.UUID: http://zoobank.org/0d281489-c0c6-47b4-9884-f820806485b7

Iceberg discharge events in the northwest Pacific and related sequence of Kamchatka glaciations over the last 190 kyr

Evidence of meltwater and ice rafted debris from the Tenji and Detroit seamounts in the northwestern corner of the North Pacific are key to understanding ice sheet dynamics across the Kamchatka Region. Marine isotopic stages 6.5–1 were established in this study for the Tenji Seamount sediment core based on accelerator mass spectrometry (AMS) 14C data, benthic foraminifera δ18O stratigraphy, and relative paleointensity excursions. Records of planktic foraminifera δ18O and ice rafted debris (IRD) in sediment cores pertaining to the last 190 kyr were used to outline several periods of surface water freshening and increased accumulation of coarse terrigenous grains induced by iceberg supply and melting in the northwest Pacific. Iceberg discharge events (IDEs) were reconstructed over the last and penultimate glacial periods in the central and eastern parts of the Okhotsk Sea and southwestern part of the Bering Sea using relevant published proxies. Similar reconstructions of IDEs were also performed for two published sediment cores from the Detroit Seamount. Synthesis of planktic foraminifera δ18O and IRD records along with other related proxies from the studied areas concordantly revealed five IDEs in the northwest Pacific and its marginal seas during the last 190 kyr: IDE 1 (42–29 ka), IDE 2 (76–57 ka), IDE 3 (118–110 ka), IDE 4 (152–141 ka), and IDE 5 (179–160 ka). Data showed that IDEs 4–1 occurred at low values of Earth obliquity and under a weak Aleutian Low, facilitating snowfall precipitation and enhancing glacier formation at Kamchatka, which is a priority area for capturing atmospheric moisture transferred into northeast Asia. Compared with the other IDEs, IDEs 2 and 5 were more pronounced and prolonged events over the last 190 kyr. In addition, IDE 2 was also characterised by a catastrophic and short IRD peak that was probably forced by the influx of lake water from the Central Kamchatka Depression. It is likely that IDEs 2 and 1 occurred during phases I (more extensive) and II (less extensive) of the published Kamchatka glaciations during the Late Pleistocene.

THE STATE OF INTERNATIONAL RELATIONSHIP BETWEEN THE FORMATION AND ACTIVITY OF MOUNTAIN GLACES OF UZBEKISTAN

This article describes the systematic study of the base surfaces in the formation and development of mountain glaciers of Uzbekistan and their current state.

Geomorphological information mapping of debris-covered ice landforms using Google Earth: An example from the Pico de Posets, Spanish Pyrenees

Geomorphological mapping records ‘snapshots’, making it difficult to investigate change and sensitivity in changing environments. The high resolution now available in Google Earth (GE) permits re-investigation of landscape features/landforms previously recorded in the literature or mapped. Transects across geomorphologically interesting locations can be provided with decimal degree WGS 84 locations and bearings via GE. Landform elements are identified, located and coded onto transects that summarise geomorphological information. Transects crossing rock cliffs, scree slopes, snowpatches, protalus ramparts, ‘vanishing’ glaciers, moraines and rock glaciers are investigated using GE on the Pico de Posets in the Spanish Pyrenees. Observations of geometry/form, materials and processes involved in ice and sediment movement are linked to the Randolph Glacier Inventory and map records. The transect mapping shows that accumulated weathered rock debris insulated a remnant Little Ice Age glacier that formed a lateral moraine and a contiguous rock glacier as the glacier wasted down. Landforms previously considered to indicate permafrost are shown not to do so. Glacigenic formation of moraines, protalus rampart and rock glaciers provides the simplest explanation for their origin.

Relations between climate change and mass movement: Perspectives from the Canadian Cordillera and the European Alps

Earth's climate is warming and will continue to warm as the century progresses. High mountains and high latitudes are experiencing the greatest warming of all regions on Earth and also are some of the most sensitive areas to climate change, in part because ecosystems and natural processes in these areas are intimately linked to the cryosphere. Evidence is mounting that warming will further reduce permafrost and snow and ice cover in high mountains, which in turn will destabilize many slopes, alter sediment delivery to streams, and change subalpine and alpine ecosystems. This paper contributes to the continuing discussion of impacts of climate change on mountain environments by comparing and discussing processes and trends in the mountains of western Canada and the European Alps. We highlight the effects of physiography and climate on physical processes occurring in the two regions. Processes of interest include landslides and debris flows induced by glacier debuttressing, alpine permafrost thaw, changes in rainfall regime, formation and sudden drainage of glacier- and moraine-dammed lakes, ice avalanches, glacier surges, and large-scale sediment transfers due to rapid deglacierization. Our analysis points out the value of integrating observations and data from different areas of the world to better understand these processes and their impacts.