scholarly journals Quaternary geology of part of the McLeod Lake map area (NTS 093J), central British Columbia: lithostratigraphy, glacial history, and chronology

2017 ◽  
Vol 54 (10) ◽  
pp. 1063-1084
Author(s):  
David A. Sacco ◽  
Brent C. Ward ◽  
Olav B. Lian ◽  
Denny E. Maynard ◽  
Marten Geertsema
Keyword(s):  
Quaternary Geology ◽  
Similar Data ◽  
Ice Flow ◽  
Surficial Geology ◽  
Front Position ◽  
Aeolian Activity ◽  
Stratigraphic Record ◽  
Glaciofluvial Deposits ◽  
Flow Features ◽  
Ice Retreat

The coalescence and subsequent divergence of glaciers near the McLeod Lake map area during the last (Fraser) glaciation are recorded by landforms, ice-flow indicators, and the distribution of sediments. Ice initially flowed into the study area from the northwest, with at least one fluctuation in the ice-front position. Ice flow during glacial maximum was generally to the northeast and transitioned to the east during deglaciation. The Quaternary stratigraphic record spans the Fraser Glaciation and is represented by a sequence of advance glaciolacustrine sediments, multiple till units, retreat glaciolacustrine and glaciofluvial sediments, and associated postglacial aeolian material. The surficial geology is dominated by thick, streamlined till that thins where relief is high. Glaciofluvial outwash occurs mostly in northeast- and southeast-trending meltwater channels, while ice-contact glaciofluvial deposits and ablation till occur in depressions throughout the region. Extensive glaciolacustrine deposits blanket low-lying regions in the southern parts of the study area. Meltwater and ice-flow features suggest that deglaciation in the region was dominantly frontal retreat and that ice was largely active as it retreated through the study area. Postglacial aeolian activity was brief; optical dating on K-feldspar from aeolian landforms indicates that the landforms had stabilized by between 8.71–10.71 and 12.3–14.3 ka, and provides minimum ages for ice retreat. The data from the study area are evaluated with similar data from adjacent regions to develop an ice-flow history, and refine the conceptual model of deglaciation for the northern Interior Plateau.

scholarly journals Recent ice-surface-elevation changes of Fleming Glacier in response to the removal of the Wordie Ice Shelf, Antarctic Peninsula

2010 ◽  
Vol 51 (55) ◽  
pp. 97-102 ◽  
Author(s):  
J. Wendt ◽  
A. Rivera ◽  
A. Wendt ◽  
F. Bown ◽  
R. Zamora ◽  
...  
Keyword(s):  
Antarctic Peninsula ◽  
Regional Climate ◽  
Airborne Lidar ◽  
Similar Data ◽  
Ice Shelf ◽  
International Polar Year ◽  
Ice Flow ◽  
Ice Shelves ◽  
Elevation Changes ◽  
The Antarctic

AbstractRegional climate warming has caused several ice shelves on the Antarctic Peninsula to retreat and ultimately collapse during recent decades. Glaciers flowing into these retreating ice shelves have responded with accelerating ice flow and thinning. The Wordie Ice Shelf on the west coast of the Antarctic Peninsula was reported to have undergone a major areal reduction before 1989. Since then, this ice shelf has continued to retreat and now very little floating ice remains. Little information is currently available regarding the dynamic response of the glaciers feeding the Wordie Ice Shelf, but we describe a Chilean International Polar Year project, initiated in 2007, targeted at studying the glacier dynamics in this area and their relationship to local meteorological conditions. Various data were collected during field campaigns to Fleming Glacier in the austral summers of 2007/08 and 2008/09. In situ measurements of ice-flow velocity first made in 1974 were repeated and these confirm satellite-based assessments that velocity on the glacier has increased by 40–50% since 1974. Airborne lidar data collected in December 2008 can be compared with similar data collected in 2004 in collaboration with NASA and the Chilean Navy. This comparison indicates continued thinning of the glacier, with increasing rates of thinning downstream, with a mean of 4.1 ± 0.2 m a−1 at the grounding line of the glacier. These comparisons give little indication that the glacier is achieving a new equilibrium.

A reconstruction of glacial events in southeastern New Brunswick

1991 ◽  
Vol 28 (10) ◽  
pp. 1594-1612 ◽  
Author(s):  
Marc Foisy ◽  
Gilbert Prichonnet
Keyword(s):  
New Brunswick ◽  
Ice Flow ◽  
Ice Cap ◽  
The North ◽  
Lithostratigraphic Units ◽  
Glaciofluvial Deposits ◽  
Southern Border ◽  
Late Wisconsinan ◽  
Radial Outflow ◽  
North And South

Sedimentological and petrographical data obtained from five sections located north and south of the Caledonian Highlands in southeastern New Brunswick demonstrate the existence of three main till units and one glaciofluvial unit, which have been grouped in four distinct lithostratigraphic units. The lower till was deposited by a glacier that overrode the Caledonian Highlands from northwest to southeast and advanced as far as Nova Scotia during Middle(?) to Late Wisconsinan times. The overlying middle till from the north provides evidence that ice continued to advance across the Highlands from northwest toward southeast and then was partially overwhelmed by another glacier that was advancing southwest along the southern border of the Highlands: this glacier deposited a coeval middle till. During Late Wisconsinan deglaciation, ice separated into two masses: a residual ice cap with radial outflow from the Highlands; and a lobe in the Chignecto Bay, retreating toward the northeast. The existence of a plateau ice cap is demonstrated by the presence of till and glaciofluvial deposits in the upper part of all surveyed sections, and is supported by the sequence of ice flow patterns recorded by striae and the centrifugal distribution of meltwater flow indicators. The weak development of soils, the fresh appearance of till and morainic landforms, and the lack of periglacial features throughout the area, especially on the Highlands, all favour the interpretation that the Caledonian Highlands were not a nunatak during the glacial maximum of the Late Wisconsinan Substage.

The late Quaternary geology of the Chalk River region, Ontario and Quebec

1982 ◽  
Vol 19 (6) ◽  
pp. 1218-1231 ◽  
Author(s):  
N. R. Catto ◽  
R. J. Patterson ◽  
W. A. Gorman
Keyword(s):  
Forest Fires ◽  
Late Quaternary ◽  
Glacial Ice ◽  
Ottawa River ◽  
The North ◽  
Discharge Rates ◽  
Aeolian Activity ◽  
River Region ◽  
Ice Retreat ◽  
Time Changes

Glacial ice covered the Chalk River area through most of the Wisconsin Stage. About 11 300 years ago, an ice retreat was followed immediately by a short incursion of Champlain Sea waters, which deposited at least 2.5 m of clay, silt, and sand. A local readvance, probably associated with the St. Narcisse event, deposited till on the marine sediments. Following the final retreat of the ice from the area, lacustrine and aeolian deposition occurred locally for a short time.About 10 500 years ago, the North Bay drainage route opened, greatly increasing the discharge of the Ottawa River. A faint terrace at a present elevation of 209 m probably formed at this time. Changes in the drainage routes of proglacial lakes and in the rate of ice retreat caused a general decrease in discharge rates, and resulted in the formation of pronounced terraces, now at 180, 160, and 129 m, and fainter terraces at 170, 141, and 137 m. By about 5000 years BP, the North Bay outlet closed, and the river fell to approximately 111 m, its present elevation at Chalk River.During the whole period of terrace formation, alluvial sands were being deposited and, as river levels fell, exposed sands were reworked by the wind until anchored by vegetation. Charcoal horizons within the aeolian sequences indicate that forest fires occasionally destroyed the vegetation cover, re-initiating aeolian activity. Locally, active dunes are present near Chalk River, but most of the area has been stabilized by vegetation.

Postglacial emergence of Amund and Ellef Ringnes islands, Nunavut: implications for the northwest sector of the Innuitian Ice Sheet

2004 ◽  
Vol 41 (3) ◽  
pp. 271-283 ◽  
Author(s):  
Nigel Atkinson ◽  
John England
Keyword(s):  
Late Holocene ◽  
Ice Sheet ◽  
The Arctic ◽  
Ice Flow ◽  
Geological Evidence ◽  
Level Curves ◽  
Ice Load ◽  
Holocene Transgression ◽  
Flow Features ◽  
Late Wisconsinan

This paper presents relative sea-level curves from Amund and Ellef Ringnes islands, northwest Queen Elizabeth Islands. These curves are of exponential form and record continuous, ongoing Holocene emergence, although northwest Ellef Ringnes Island is experiencing a late Holocene transgression. Isobases drawn on postglacial shorelines rise southeastward towards an uplift centre in Norwegian Bay. These suggest the Ringnes Islands occupied the northwest radius of the Innuitian uplift, which is congruent with glacial geological evidence suggesting parts of the Ringnes Islands were covered by the Late Wisconsinan Innuitian Ice Sheet. The isobases provide a provisional reconstruction of glacioisostatic recovery within the northwest Innuitian uplift. Their pattern supports earlier reconstructions that maximum Late Wisconsinan ice thickness occurred across Norwegian Bay, marking the position of an ice divide, which is consistent with ice-flow features on Amund Ringnes Island. They record the diminishing thickness of the Innuitian Ice Sheet from Norwegian Bay to the Arctic Ocean. The absence of an isobase embayment across the Ringnes Islands suggests a relatively uniform ice load across both islands and Hassel and Massey sounds. Parallel isobases across Peary Channel indicate this ice load extended beyond Massey Sound, although their northward deflection suggests an increasing influence of the former Axel Heiberg Island ice load.

scholarly journals Quaternary geology and till composition north of Wager Bay, Nunavut: results from the GEM Wager Bay Surficial Geology Project

2015 ◽  
Author(s):  
I McMartin ◽  
J E Campbell ◽  
L A Dredge ◽  
A N LeCheminant ◽  
M W McCurdy ◽  
...  
Keyword(s):  
Quaternary Geology ◽  
Surficial Geology

scholarly journals Ice-sheet flow features and rheological parameters derived from precise altimetric topography

1996 ◽  
Vol 23 ◽  
pp. 277-283 ◽  
Author(s):  
F. Rémy ◽  
C. Ritz ◽  
L. Brisset
Keyword(s):  
Shear Stress ◽  
Flow Direction ◽  
Ice Sheet ◽  
Rheological Parameters ◽  
Topographic Map ◽  
Radar Altimeter ◽  
Sheet Flow ◽  
Ice Flow ◽  
Exponential Factor ◽  
Flow Features

For the first time high-quality coverage of the ERS-1 radar altimeter provides a very accurate surface topographic map covering 80% of the Antarctic ice sheet that can contribute significantly to glaciological studies such as ice-sheet flow modelling. The topography allows estimation of the ice-flow direction, the balance velocity and the basal shear stress. A relationship between shear stress, basal temperature and a parameter related to strain rate helps in mapping the behaviour anomalies of these parameters. Longitudinal stress, sliding, bedrock topography and variation in the pre-exponential factor of the flow law are found to play a major role in the ice-flow pattern. This relation can also be used to estimate rheological parameters: the Glen exponent n is found to be 1 for T < −10°C and 3–4 for higher temperatures, where Q is found to be 70 kJ mol−1.

scholarly journals Report on ice-flow history, deglacial chronology, and surficial geology, Foxe Peninsula, southwest Baffin Island, Nunavut

2007 ◽  
Author(s):  
D J Utting ◽  
J C Gosse ◽  
D A Hodgson ◽  
M S Trommelen ◽  
K J Vickers ◽  
...  
Keyword(s):  
Baffin Island ◽  
Ice Flow ◽  
Surficial Geology

scholarly journals Glacial dynamics in pre-Alpine narrow valleys during the Last Glacial Maximum inferred by lowland fluvial records (northeast Italy)

2018 ◽  
Vol 6 (3) ◽  
pp. 809-828 ◽  
Author(s):  
Sandro Rossato ◽  
Anna Carraro ◽  
Giovanni Monegato ◽  
Paolo Mozzi ◽  
Fabio Tateo
Keyword(s):  
Last Glacial Maximum ◽  
Mineralogical Composition ◽  
Glacial Maximum ◽  
Last Glacial ◽  
Wide Range ◽  
Stratigraphic Record ◽  
Glaciofluvial Deposits ◽  
Glacial Dynamics ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract. During the Last Glacial Maximum (LGM), most of the major glaciated basins of the European Southern Alps had piedmont lobes with large outwash plains; only a few glaciers remained within the valley. Piedmont glaciers have left well-preserved terminal moraines, which allow for investigations to be carried out and inferences to be made regarding their evolution and chronology. Valley glaciers' remnants, on the contrary, are often scantly preserved, and changes can only be detected through correlations with glaciofluvial deposits in downstream alluvial basins. The Brenta glacial system's dynamics in the glacier's terminal tract have been inferred through a wide range of sediment analysis techniques on an alluvial stratigraphic record of the Brenta megafan (northeast Italy), and via the mapping of in-valley glacial/glaciofluvial remnants. Glaciers flowing across narrow gorges could possibly be slowed/blocked by such morphology, and glacial/sediment fluxes may then be diverted to lateral valleys. Moreover, narrow valleys may induce glaciers to bulge and form icefalls at their front, preventing the formation of terminal moraines. The Brenta Glacier was probably slowed/blocked by the narrow Valsugana Gorge downstream of Primolano and was effectively diverted eastwards across a wind gap (Canal La Menor Valley), joining the Cismon/Piave glaciers near Rocca and ending ∼2 km downstream. The Cismon and Piave catchments started to contribute to the Brenta system just after 27 ka cal BP until at least ∼19.5 ka cal BP. After the glaciers collapsed, the Piave River once again flowed into its main valley, whilst the Cismon continued to merge with the Brenta. This investigation shows that glacial catchments may vary significantly over time during a single glaciation in rugged Alpine terrains. Sand petrography and the chemical/mineralogical composition of sediments are powerful proxies for tracing such variations, as they propagate through the glacial and glaciofluvial systems and can be recognized in the alluvial stratigraphic record far downstream from the glacier front.

The late Quaternary stratigraphic record northwest of Montréal: regional ice-sheet dynamics, ice-stream activity, and early deglacial events

2006 ◽  
Vol 43 (4) ◽  
pp. 461-485 ◽  
Author(s):  
Martin Ross ◽  
Michel Parent ◽  
Beatriz Benjumea ◽  
James Hunter
Keyword(s):  
Late Quaternary ◽  
Late Glacial ◽  
Ice Flow ◽  
Glacial Sediments ◽  
Ice Stream ◽  
Digital Elevation ◽  
Flow Features ◽  
Ice Sheet Dynamics ◽  
Late Wisconsinan ◽  
Elevation Model

The Quaternary sediments of previously unstudied buried valleys and sections near Montréal are analyzed and other sites are revisited to further develop the stratigraphic framework of the St. Lawrence Lowland and to establish regional glacial and deglacial models. The southwest-trending buried valleys were investigated by stratigraphic drilling and high-resolution seismic profiling. The Quaternary succession consists, from base to top, of proximal glaciolacustrine sediments, two superposed till sheets (Argenteuil and Oka tills) of inferred Late Wisconsinan age, and Champlain Sea sediments. The glacial sediments of this sequence record an ice advance toward south (Argenteuil Till) followed by an abrupt ice-flow shift toward the southwest (Oka Till). Compositional and geomorphic data indicate that Oka Till is ubiquitous and is associated with a regional set of glacial landforms. The analysis of a regional digital elevation model in combination with published ice-flow indicators shows convergent flow patterns from the Ottawa–Montréal–Adirondack regions toward the Lake Ontario basin. Landforms produced by the inferred ice stream are locally crosscut by southward-trending ice-flow features. Hence southward flow in the upper St. Lawrence Valley seemingly took place in two distinct contexts: (1) during full glacial conditions, as ice margins stood at or near the late glacial maximum limits, and (2) during late deglaciation, as a post-ice stream reequilibration mechanism. Early deglacial events in the study area were also characterized by subglacial meltwater channelling and erosion along the valleys, subaquatic outwash deposition in glacial Lake Candona, and rapid infill of the valleys during the early stages of the ensuing Champlain Sea.

scholarly journals Transient glacier response with a higher-order numerical ice-flow model

2002 ◽  
Vol 48 (162) ◽  
pp. 467-477 ◽  
Author(s):  
Frank Pattyn
Keyword(s):  
Flow Model ◽  
Higher Order ◽  
Ice Flow ◽  
Surface Mass ◽  
Front Position ◽  
Significant Difference ◽  
Dynamic Experiments ◽  
Stress Profiles ◽  
Horizontal Grid ◽  
Higher Order Models

AbstractIn this paper, a higher-order numerical flowline model is presented which is numerically stable and fast and can cope with very small horizontal grid sizes (<10 m). The model is compared with the results from Blatter and others (1998) on Haut Glacier d’Arolla, Switzerland, and with the European Ice-Sheet Modelling Initiative benchmarks (Huybrechts and others, 1996). Results demonstrate that the significant difference between calculated basal-drag and driving-stress profiles in a fixed geometry disappears when the glacier profile is allowed to react to the surface mass-balance conditions and reaches a steady state. Dynamic experiments show that the mass transfer in higher-order models occurs at a different speed in the accumulation and ablation areas and that the front position is more sensitive to migration compared to the shallow-ice approximation.

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