Glaciological Research Articles

Determining glacier flow direction from till fabrics

Field and experimental data indicate that fabrics of sheared basal tills, based on particle orientations and on anisotropy of magnetic susceptibility, are inclined relative to the macroscopic plane of shear. As a result, if this plane is tilted with a transverse component, one of the longest-standing axioms of glacial geology—that particles in basal till are preferentially oriented parallel to the direction of shear—is not strictly true. The resultant correction to the shearing direction increases with the transverse and longitudinal components of shear-plane inclination and with the magnitude of the fabric inclination relative to the shear plane. Azimuthal corrections calculated herein range from being negligible to a few tens of degrees for reasonable ranges of shear-plane tilt. The past success of fabric azimuths as indicators of flow direction, despite the absence of this correction, likely reflects the clustering of shear planes about the horizontal in basal tills. However, on the flanks of accreting subglacial bedforms, shear-plane attitudes may well conform to the local bedform slope. As illustrated with hypothetical fabrics of drumlins and flutes, azimuthal corrections can in that case be sufficiently large and systematic to seriously affect interpretations of bedform genesis.

First measurement of ice‐bedrock interface of alpine glaciers by cosmic muon radiography

AbstractThe shape of the bedrock underneath alpine glaciers bears vital information on the erosional mechanism related to the flow of ice. So far, several geophysical exploration methods have been proposed to map the bedrock topography though with limited accuracy. Here we illustrate the first results from a technology, called cosmic ray muon radiography, newly applied in glacial geology to investigate the bedrock geometry beneath the Aletsch Glacier situated in the Central Swiss Alps. For this purpose we installed new cosmic muon detectors made of emulsion films at three sites along the Jungfrau railway tunnel and measured the shape of the bedrock under the uppermost part of Aletsch Glacier (Jungfraufirn). Our results constrain the continuation of the bedrock‐ice interface up to a depth of 50 m below the surface, where the bedrock underneath the glacier strikes NE‐SW and dips at 45° ± 5°. This documents the first successful application of this technology to a glaciated environment.

Geomorphology of the Chippewa River delta of Glacial Lake Saginaw, central Lower Michigan, USA

We introduce, characterize, and interpret the geomorphic history of a relict, Pleistocene-aged delta of the Chippewa River in central Lower Michigan. The broad, sandy Chippewa delta developed into various stages of Glacial Lake Saginaw, between ca. ≈17 and 15ka·BP (calibrated ages). Although the delta was first identified in 1955 on a statewide glacial geology map, neither its extent nor its Pleistocene history had been previously determined. The delta is typically forested, owing to its wet, sandy soils, which stand out against the agricultural fields of the surrounding, loamy lake plain sediments. The delta heads near the city of Mt Pleasant and extends eastward onto the Saginaw Lowlands, i.e., the plain of Glacial Lake Saginaw. Data from 3285 water well logs, 180 hand augered sites, and 185 points randomly located in a GIS on two-storied (sand over loam) soils were used to determine the extent, textural properties, and thickness of the delta. The delta is ≈18km wide and ≈38km long and is sandy throughout. Deltaic sediments from neighboring rivers that also drained into Glacial Lake Saginaw merge with the lower Chippewa delta, obscuring its boundary there. The delta is thickest near the delta's head and in the center, but thins to 1–2m or less on its eastern margins. Mean thicknesses are 2.3–2.9m, suggestive of a thin sediment body, frequently impacted by the waves and fluctuating waters of the lakes. Although beach ridges are only weakly expressed across the delta because of the sandy sediment, the coarsest parts of the delta are generally coincident with some of these inferred former shorezones and have a broad, incised channel that formed while lake levels were low. The thick upper delta generally lies above the relict shorelines of Glacial Lakes Saginaw and Arkona (≈17.1 to ≈16ka·BP), whereas most of the thin, distal delta is associated with Glacial Lake Warren (≈15ka·BP). Together, these data suggest that the Chippewa delta formed and prograded as lake levels in the Saginaw Lowlands alternated and episodically fell. The result is a delta that is comparatively thin, expansive, and sandy. In some places, these sands have subsequently been reworked into fields of small parabolic dunes.

Diversity and abundance of microbial eukaryotes in stream sediments from Svalbard

Microbial eukaryotes are increasingly being recognised for their role in global biogeochemical cycles, yet very few studies have focussed on their distribution in high-latitude stream sediments, an important habitat which influences stream water nutrient chemistry. In this study, we present the first comparison of microbial eukaryotes from two different polar habitats by determining the abundance and taxonomic affiliation of 18S rRNA gene fragments recovered from four sediment samples in Svalbard: two from a glaciated catchment and two from an unglaciated permafrost-dominated catchment. Whilst there was no difference between the two catchments in terms of Rao’s phylogenetic diversity (0.18±0.04, 1SD), the glaciated catchment samples had slightly higher richness (138–139) than the unglaciated catchment samples (67–106). At the phylum level, Ciliophora had the highest relative abundance in the samples from the glaciated catchment (32–63%), but only comprised 0–17% of the unglaciated catchment samples. Bacillariophyta was the most abundant phylum in one of the samples from the unglaciated catchment (43%) but phototrophic microbial eukaryotes only formed a minor component of the glaciated catchment samples (<2%), suggesting that in these environments the microbial eukaryotes are predominantly heterotrophic (chemotrophic). This is in contrast to previously published data from Robertson Glacier, Canada where the relative abundance of chlorophyta (phototrophs) in three samples was 48–57%. The contrast may be due to differences in glacial hydrology and/or geology, highlighting the variation in microbial eukaryote communities between nominally similar environments.

Notes on the glacial geology of the Glen of Aherlow

Notes on the glacial geology of the Glen of Aherlow

Keeping the bay in Glacier Bay National Park: Introducing glacier science to the United States Supreme Court

ABSTRACT In 2000, seventy-five years after the founding of Glacier Bay National Monument, the United States Supreme Court authorized the State of Alaska to begin legal proceedings related to the ownership of ‘certain marine submerged lands in southeast Alaska’ including the submerged lands contained within what is now Glacier Bay National Park. This narrative presents a summary of how glacier science (glacial geology and glaciology) became an integral part of the argument prepared and presented by the United States Government in response to the State of Alaska's Complaint.

Study of annual mass balance (2011-2013) of Rikha Samba Glacier, Hidden Valley, Mustang,Nepal

Although Himalayan glaciers are of particular interest in terms of future water supplies, regional climate changes, and sea-level rises, little is known about them due to lack of reliable and consistent data. There is a need for monitoring these glaciers to bridge this knowledge gap and to provide field measurements necessary to calibrate and validate the results from different remote sensing operations. Therefore, glaciological observations have been carried out by the Cryosphere Monitoring Project (CMP) since September 2011 on Rikha Samba Glacier in Hidden valley, Mustang district in western Nepal in order to study its annual mass balance. This paper presents the first results of that study. There are 10 glaciers in Hidden Valley, named G1, G2, G3, up to G10. Of these, G5 is the Rikha Samba Glacier, which has the largest area (5.37 km 2 ) in this valley and the highest and lowest altitudes (6,476 and 5,392 m a.s.l., respectively). The glacier mass balance discussed in this paper was calculated using the glaciological method and the equilibrium line altitude (ELA). The glacier showed a negative annual point mass balance along the longitudinal profile of its lower part from September 10, 2011 to October 3, 2012. Stake measurements from October 4, 2012 to September 30, 2013 indicated a negative areal average of annual mass balance -0.088±0.019 m w.e. for the whole glacier. Based on these observations, the ELA of the Rikha Samba Glacier is estimated at 5,800 m a.s.l. in 2013. This negative balance may be due to rising air temperatures in the region, which have been incrementally rising since 1980 accompanied by little or no significant increase in precipitation in that period. The negative mass balance confirms the general shrinking trend of the glacier.

The Lithological Characteristics of the Glacial Deposits of County Longford

A preliminary examination of the glacial geology of Co. Longford is presented. Four lithologically distinct facies of diamicton and three associated glaciofluvial members are examined in terms of their petrographic composition. The units are then interpreted with reference to direction of ice movement, nature of deglaciation and bedrock geology.

PAST Gateways (Palaeo-Arctic Spatial and Temporal Gateways): Introduction and overview

This special issue relates to the Second International Conference of the PAST Gateways (Palaeo-Arctic Spatial and Temporal Gateways) network which was held in Trieste, Italy in 2014. Twenty five papers are included and they address topics under four main themes: (1) The growth and decay of Arctic ice sheets; (2) Arctic sea ice and palaeoceanography; (3) Terrestrial Arctic environments and permafrost change; and (4) Holocene Arctic environmental change. Geographically the focus is circum-Arctic; the special issue includes detailed regional studies from Greenland, Scandinavia, Russia, and Arctic North America and the adjoining seas, as well as a series of synthesis-type, review papers on Fennoscandian Ice Sheet deglaciation and Holocene Arctic palaeo-climate change. The methodologies employed are diverse and include marine sediment core and geophysical investigations, terrestrial glacial geology and geomorphology, isotopic analysis of ground ice, palaeo-ecological analysis of lacustrine and terrestrial sedimentary archives, geochronology and numerical ice sheet modeling.

Colophon, contents, preface

This issue of​ Review of Survey Activities presents a selection of 24 papers reflecting the wide spectrum of current activities of the Geological Survey of Denmark and Greenland, from the microscopic to the plate-tectonic level. The Survey’s activities in Denmark are illustrated by 11 papers covering widely different subjects including groundwater management, pesticide monitoring, 3D urban geology, the regional Danish potential for geothermal energy, Palaeozoic stratigraphy from borehole logs, enhancement of oil production by injection of ‘smart’ water and glacial geology. Activities in Greenland are illustrated by eight papers on Precambrian crustal evolution and mineralisation processes in South-East and northern West Greenland, fundamental magma processes in the Skaergaard intrusion, onshore and offshore seismological studies, and on long-term monitoring of the Greenland ice sheet and sea-ice variability.&#x0D; International studies by the Survey are represented by two papers describing a large Nordic CO2-storage project and a pilot study of burial and exhumation along the eastern passive margin of Labrador and Newfoundland using apatite fission track analysis. Finally, three papers describe new developments in the digital access to, and handling of Greenland-related geodata and presentation of a new smartphone- and tablet-based app for effective handling of geological and sample data during field work.

Elsewhere in Science: Feminist glaciology, blogging, and more

Elsewhere in Science: Feminist glaciology, blogging, and more

Indian Himalayan Capacity and Adaptation Programme: Capacity-Building in Himalayan Glaciology

Indian Himalayan capacity and adaptation programme : capacity-building in Himalayan glaciology

Report of the glaciological survey of 2015

Report of the glaciological survey of 2015

Annotated bibliography of the Russian languages literature on glaciology for 2013

ПРЕДЛАГАЕМАЯ БИБЛИОГРАФИЯ ПРОДОЛЖАЕТ ЕЖЕГОДНЫЕ АННОТИРОВАННЫЕ СПИСКИ РУССКОЯЗЫЧНОЙ ЛИТЕРАТУРЫ ПО ГЛЯЦИОЛОГИИ, КОТОРЫЕ РЕГУЛЯРНО ПУБЛИКОВАЛИСЬ В ПРОШЛОМ. ПОМИМО РАБОТ ТЕКУЩЕГО ГОДА, В СПИСКЕ ВСТРЕЧАЮТСЯ РАБОТЫ БОЛЕЕ РАННИХ ЛЕТ, ПО ТЕМ ИЛИ ИНЫМ ПРИЧИНАМ НЕ ВОШЕДШИЕ В ПРЕДЫДУЩИЕ БИБЛИОГРАФИЧЕСКИЕ СПИСКИ.

A new glacial isostatic adjustment model of the Innuitian Ice Sheet, Arctic Canada

A reconstruction of the Innuitian Ice Sheet (IIS) is developed that incorporates first-order constraints on its spatial extent and history as suggested by regional glacial geology studies. Glacial isostatic adjustment modelling of this ice sheet provides relative sea-level predictions that are in good agreement with measurements of post-glacial sea-level change at 18 locations. The results indicate peak thicknesses of the Innuitian Ice Sheet of approximately 1600 m, up to 400 m thicker than the minimum peak thicknesses estimated from glacial geology studies, but between approximately 1000 to 1500 m thinner than the peak thicknesses present in previous GIA models. The thickness history of the best-fit Innuitian Ice Sheet model developed here, termed SJD15, differs from the ICE-5G reconstruction and provides an improved fit to sea-level measurements from the lowland sector of the ice sheet. Both models provide a similar fit to relative sea-level measurements from the alpine sector. The vertical crustal motion predictions of the best-fit IIS model are in general agreement with limited GPS observations, after correction for a significant elastic crustal response to present-day ice mass change. The new model provides approximately 2.7 m equivalent contribution to global sea-level rise, an increase of +0.6 m compared to the Innuitian portion of ICE-5G. SJD15 is qualitatively more similar to the recent ICE-6G ice sheet reconstruction, which appears to also include more spatially extensive ice cover in the Innuitian region than ICE-5G.

The annotated bibliography of Russian glaciological literature in 2012

Предлагаемая библиография продолжает ежегодные аннотированные списки русскоязычной литературы по гляциологии, которые регулярно публиковались в прошлом. Помимо работ текущего года, в списке встречаются работы более ранних лет, по тем или иным причинам не вошедшие в предыдущие библиографические списки.

GPR and Seismic surveying in the World War I Scenario of Punta Linke (Ortles-Cevedale Group, Italian Alps)

The Ortles-Cevedale Group was the setting of repeated clashes occurring under extreme conditions and at the highest altitudes of all fightings in the Great War (WWI). The research scenario associated with the group is very challenging because modern research faces a series of logistical and climatic obstacles. The gradual retreat of glaciers has unearthed several archaeological remains of WWI such as barracks, barbed wire, military ammunition, weapons and other materials. The study site is the saddle between M. Vioz and Punta Linke, where the Historic War Museum of Pejo, under the direction of the Archaeological Service of the Province of Trento (Soprintendenza per i Beni Culturali, Ufficio Beni Archeologici), started an archaeological excavation in the year 2009 of some of the infrastructure of the cableway station, which also includes a tunnel section in the bedrock. The saddle is placed at the head of Forni Glacier. GPR and seismic imaging was the best survey choice to characterize the glaciological and geo-archaeological context and to find structures or remains within the ice mass. Geophysical imaging spanned two campaigns in the years 2010 and 2011. The ice-rock interface was reconstructed in detail to depths greater than 45-50 m. The surface of the bedrock reveals a complex morphology, with several undulations and two rocky ridges elongated in the NNW-SSE direction. They identified some anomalous reflectors within the ice mass located near the western edge of the saddle of Punta Linke. The interpretation of radar profiles seems to indicate the presence of a tunnel in the ice, whose geometry and position is similar to others excavated in alpine glaciers during the Great War.

Glaciological and meteorological observations at the SIGMA-D site, northwestern Greenland Ice Sheet（グリーンランド氷床北西部SIGMA-Dサイトにおける雪氷・気象観測）

Glaciological and meteorological observations at the SIGMA-D site, northwestern Greenland Ice Sheet（グリーンランド氷床北西部SIGMA-Dサイトにおける雪氷・気象観測）

Ribbed moraines formed during the retreat of the Scandinavian ice sheet from eastern Himmerland, NE Jylland, Denmark

The glacial geology of Himmerland in the north-eastern part of Jylland, south of Limfjorden (Fig. 1) has never received any special attention. However, the occurrence of parallel ridges south of Torup was mentioned by Milthers (1948) who interpreted them as marginal moraines. The ridges were recently studied during mapping of eastern Himmerland. Systematic geological mapping of the area north and south of Mariager Fjord started in 2009 and was completed in 2013 (map sheet 1316 III; Pedersen et al. 2013). This was followed by the map sheet to the north (1316 IV). During the recent mapping the extent of the terrain with parallel ridges was determined (Fig. 2); the western boundary is found in Rold Skov (Pedersen &amp; Jakobsen 2005) and the eastern boundary follows an ancient coastline in eastern Himmerland. The most impressive parallel ridges occur in a forested area east of Madum Sø where the top level of the ridge crests reaches an elevation of 95 m a.s.l. However, the majority of the crests are at 60–70 m a.s.l. and most of the ridges are c. 10–15 m high. The sediments in the ridges are dominated by coarse-grained sand and gravel, and accumulations of erratic boulders are found on the surface of the ridges.

Late Quaternary glacier sensitivity to temperature and precipitation distribution in the Southern Alps of New Zealand

Glaciers respond to climate variations and leave geomorphic evidence that represents an important terrestrial paleoclimate record. However, the accuracy of paleoclimate reconstructions from glacial geology is limited by the challenge of representing mountain meteorology in numerical models. Precipitation is usually treated in a simple manner and yet represents difficult-to-characterize variables such as amount, distribution, and phase. Furthermore, precipitation distributions during a glacial probably differed from present-day interglacial patterns. We applied two models to investigate glacier sensitivity to temperature and precipitation in the eastern Southern Alps of New Zealand. A 2-D model was used to quantify variations in the length of the reconstructed glaciers resulting from plausible precipitation distributions compared to variations in length resulting from change in mean annual air temperature and precipitation amount. A 1-D model was used to quantify variations in length resulting from interannual climate variability. Assuming that present-day interglacial values represent precipitation distributions during the last glacial, a range of plausible present-day precipitation distributions resulted in uncertainty in the Last Glacial Maximum length of the Pukaki Glacier of 17.1 km (24%) and the Rakaia Glacier of 9.3 km (25%), corresponding to a 0.5°C difference in temperature. Smaller changes in glacier length resulted from a 50% decrease in precipitation amount from present-day values (−14% and −18%) and from a 50% increase in precipitation amount (5% and 9%). Our results demonstrate that precipitation distribution can produce considerable variation in simulated glacier extents and that reconstructions of paleoglaciers should include this uncertainty.