Muskeg or peat deposits cover large areas in northern Manitoba. Test sections of a newly constructed highway on peat were instrumented to investigate their performance and to develop more economical means of construction method. Test Section ‘A’ was constructed with geotextile base layer while Section ‘B’ was with geotextile and corduroys (timber logs). The test sections were constructed during winter for ease in mobilizing construction equipment at the site when the ground was frozen and were instrumented to observe its behaviour and performance. Settlements were measured using monitoring plates and pins. Ground temperatures were measured using thermistors. Porewater pressures were measured using vibrating wire piezometers. Peat in the study area has an average thickness of 4m, with the upper layer classified as fibrous and the lower layer as amorphous with strong to complete decomposition. Standard laboratory tests were conducted on bored samples from the site. Hydraulic conductivity tests were carried out at different vertical pressures to determine its permeability. Thermal conductivity was determined at frozen and unfrozen state of peat. Conventional incremental oedometer tests were conducted to determine the compressibility parameters and secondary compression indices of the peat layers. Constant-rate-of-strain (CRS) tests were also performed to supplement the results obtained from the conventional method. Isotropically-Consolidated Undrained (CIŪ) triaxial tests were carried out to determine the shear strength of peat. A commercially-available computer program was used in the numerical modelling to simulate the field performance of the instrumented sections. The results from numerical modelling were reasonably close to the measured values in the field. Laboratory-scale physical modelling was undertaken to understand further the operating mechanisms involved in the performance of the two test sections under a more controlled environment. Artificial transparent clay that has similar deformation properties with most of the natural clays and peats was used as foundation material. It allows determination of spatial deformations beneath the embankment using Particle Image Velocimetry (PIV) technique. The load-settlement behaviour in the field was also reasonably simulated in the laboratory-scaled physical model. Deformation patterns from PIV indicate that embankment with geotextile layer and corduroy has smaller settlements and lateral movements in the foundation compared to that of the embankment with only geotextile layer.

Climate change and warming have been linked to enhanced coastal erosion in the arctic. Specifically, permafrost is believed to be thawing at greater rates, and wave dynamics are expected to increase in intensity. As a result, thermokarst activity, which includes the occurrence of retrogressive thaw slumps, will be more frequent along arctic coasts. / The availability of airborne and spaceborne imagery in the arctic over the last fifty years has made possible the temporal analysis of permafrost and ground ice-related erosion. The objectives of this thesis are (1) the creation of a large scale database for horizontal coastal retreat on Herschel Island for the 1952-2000 timespan, (2) the investigation of retrogressive thaw slump activity over the same period and its relation to coastal erosion, and (3) the elaboration of stereophotogrammetric techniques to investigate retrogressive thaw slump activity volumetrically. Herschel Island, located on the northern coast of the Yukon Territory, was chosen as the study site for this research, because of the widespread presence of retrogressive thaw slumps and the lack of data for coastal erosion during the last fifty years. / Photogrammetric tools were used to create orthorectified and stereo-images of the Island for the years 1952, 1970, 2000 and 2004 from airphoto archives and Ikonos (1 m resolution) imagery. Coastal erosion was found to be stable or declining on Herschel Island except in the vicinity of retrogressive thaw slumps. In addition, retrogressive thaw slumps were identified on the imagery and observed to have increased in frequency for the 1952-2000 period. / Stereophotogrammetric analysis of two retrogressive thaw slumps showed that eroded sediment volumes from these landforms are considerable and should be included in future assessments of sediment release from arctic coasts to the oceanic shelves.

The term palsa is a Fennoscandian word for a peaty hillock or mound having a permafrost core composed of alternating layers of segregated ice lenses, and organic or mineral soil. This dissertation presents results of a study on the morphology, ecology, cryotic structure, and thermal regime of 6 palsas sites in the Schefferville area and offers a new categorization of these features based on their cryotic structure. Eighteen palsa sites were located within a 35 km radius of Schefferville and six of these sites were investigated in detail. Palsas ranged from 5.6-59.0 m in length and up to 1.1 m in height. Most were located in valleys formed by the strong ridge-valley topography of the Labrador trough. Analysis of plant macrofossils suggests a successional change from hydrophilic species 10-15 cm below the palsa surface to relatively xerophilic species on the palsa surface. The transition zone between these vegetation associations indicates when the peat surface was heaved above the water table and thus, the initiation of the palsa. Surface vegetation on the palsas is used to indicate stage or category of development. Lichens and shrubs combined with small amounts of bare peat suggest a stable palsa. Large areas of bare peat on the surface of palsas resulting from erosion indicates degradation. Healthy sedges on the palsa surface indicate aggrading conditions. Ground ice within palsas ranged from small discontinuous ice lenses within peat to large lenses at the peat mineral soil contact and within the mineral soil. The depth of snow on the palsa surface varied on both a temporal and spatial basis. Active layer depths were not greatly affected by the depth of winter snow. Climatic parameters, such as heating degree days and bright sunshine hours, were found to predict maximum active layer depths more accurately than Stefan's equation. This dissertation shows that palsas with both organic and mineral soil cores are common permafrost features in the Schefferville area

A first approximation of ground ice volume for the area surrounding Eureka, Nunavut, indicates that it comprises 30.8% of the upper 5.9 m of permafrost. Volume depends on the type of ice examined, ranging from 1.8 to 69.0% in different regions of the study area. Excess ice makes up 17.7% of the total volume of frozen materials in the study area. Melt of ground ice in the past has produced thermokarst features which include ground subsidence of up to 3.2 m, formation of tundra ponds, degradation of ice wedges, thaw slumps greater than 50 m across, gullying, and numerous active layer detachment slides. With a doubling of atmospheric carbon dioxide, the rise in mean annual temperatures for the area is projected to be 4.9 to 6.6°C, which would lengthen the thaw season and increase thaw depths by up to 70 cm. The expected geomorphic changes to the landscape are discussed.

The search for extraterrestrial life begins with understanding how life developed and evolved on our own planet. Earth's polar regions provide a unique setting conducive to developing the methodologies and techniques that will be needed to find new life forms either as living organisms or as some biological signal in a sedimentary record. / The highest latitude perennial spring system in a region of thick, continuous permafrost resides in the Arctic archipelago of northern Canada. At Expedition Fiord on Axel Heiberg Island there are two sets of springs that provide useful analogs to liquid water habitats that may have existed on Mars. The springs occur in a region with a mean annual air temperature of -15.5° C. Spring flow rates and discharge temperatures are constant throughout the year. Filamentous bacteria, biofilms and mineral precipitates occur in association with the emergent, anoxic brine flowing from the springs. / Preliminary data on the microbial composition of the spring water has been obtained by applying the culture-independent approach. The majority (76%) of the fifty-five environtaxa showed high sequence similarity to Thiomicrospira species (sulfur-oxidizing organism). Other sequences show high similarity to sulfate-reducing members of the delta (Desulfocapsa sp.) and epsilon (Sulfurospirillum sp.) proteobacterium groups. A single sequence was found to have 99% sequence similarity to species of the genus Haloanaerobium a group of low G+C Gram positive, anaerobic, halophiles (Rainey et al. 1995). / A combined flow and thermal model of the Axel Heiberg springs has demonstrated how such springs are able to persist throughout the year despite temperatures that fall to below -50°C during the winter darkness. Dissolved gases emanating from the springs provide evidence of the origin of the water for the springs as well as placing constraints upon the residence time. The gas is composed primarily of N2 with relative concentrations of Ar, Kr, and Xe almost identical to air. No O2 is detectable and Ne is 60% of air values. We believe that ~50% of this gas originates from the direct release of air by nearby alpine glaciers and local ice sheets into groundwater that infiltrates sub-ice sedimentary deposits.

Thesis (M. App. Sc.)--Carleton University, 2004. / Includes bibliographical references (p. 148-158). Also available in electronic format on the Internet.

Thesis (M.SC.) - Carleton University, 2007. / Includes bibliographical references (p. 154-161). Also available in electronic format on the Internet.

Thesis (M.A.)--The University of North Carolina at Greensboro, 2010. / Directed by Roy Stine; submitted to the Dept. of Geography. Title from PDF t.p. (viewed Jul. 19, 2010). Includes bibliographical references (p. 89-93).

Tjällossning är ett stort problem för våra vägar idag och det är något som återkommer varje år. Tjällossning för med sig följder som i sin tur kräver mycket tid och resurser för att kunna återställa dessa vägar till att återigen kunna användas för trafik. Varje år förekommer stora skador på bl.a. vägar, gånggator, parkeringar samt övriga trafikytor, vilket kräver enorma summor av pengar för att åtgärda problemet. Byggnader får sättningsskador och VA-ledningar täpps till av stora isklumpar eller så fryser de sönder, och bara detta visar vad för stora problem tjällossning kan åstadkomma. Det innebär att vägarna måste vara underhållna och skötta ganska ofta av entreprenörföretag, vilket i sin tur leder till oönskade ekonomiska konsekvenser. I värsta fall stängs den tjäldrabbade vägen av under en viss tid, som är nödvändig för många att transportera sig genom till sina destinationer. I Sverige räknar man med att ca 15 - 20.000km väg berörs av just sådana tjälproblem varje år och dessa avstängningar på den skadade delen av vägnätet leder varje år till stora kostnader för samhället till följd av dålig framkomlighet. Idag används olika metoder för att lösa problemet med tjällossning på vägar och därmed måste olika ekonomiska summor betalas. Och frågan blir vilken/vilka metoder är mest effektivast och användbara i dagsläget, samt med bäst ekonomiskt vinst? / Soil frost thawing is a big problem for our roads today, and its something that comes over again every year on different type of roads.  Soil frost thawing brings consequences, which in turn requires much time and resources to restore these roads to once again be used for traffic.Every year, big damages on the roads, streets, parking area, and ''traffic area'' usually occur and a great deal of money is spent to remedy these problems. Buildings are given damage-recompense 'and water and sewage pipes are closed off by big lumps of ice or they freeze until they break; this alone shows the extent of the problem that soil frost thawing can cause. This means that the roads must be maintained and managed quite frequently by entrepreneurial companies which in turn leads to great economic consequences and in worst case maybe the road has to shut down, that is very necessary for many people to transport themselves to their destinations during a period of time. In Sweden it is estimated that approximately 15 - 20.000km route affected by precisely such soil frost thawing every year, and these shutdowns on the damaged part of the road network leads every year to considerable costs for society due to poor accessibility.Today, they use different methods to solve the problem with the soil frost thawing on roads and thus have different economic sums paid. The question then becomes, which method is most effective and useful today as well as yields most economic profit?

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