Temperature Observations in Bergschrunds and Their Relationship to Cirque Erosion

Battle, W. R. B.; Lewis, W. V.

doi:10.1086/625910

Cited by 41 publications

(48 citation statements)

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“…Longer-term glacier fluctuations, with attendant thinning and thickening of the ice body, could result in large areas of marginal and headwall rock surfaces being exposed to the randklu/t weathering environment over long periods of time. The data and observations from Boundary Glacier support an idea, suggested by Battle (1960), that open and shallow randklu/ts, rather than closed and deep bergschrunds, are a focus of weathering at glacier margins and thus a potential factor in cirque development. …”

supporting

confidence: 69%

“…10hnson (1941) questioned this role of melt water in bergschrunds. Later, Battle and Lewis (1951) and Battle (1960) cast doubt on these ideas through their observations in deep bergschrunds where they found stable temperatures at or below freezing and little physical evidence of frost-shattering. Furthermore, they pointed out that, in temperate glaciers with basal ice at the pressure melting-point, melt water would be unlikely to freeze.…”

Section: Research Contextmentioning

confidence: 99%

“…Priestley (1923), Lewis (1938), and Fisher (1955) postulated that a cirque wall hundreds of meters high could be produced by the migration of weathering zones up and down as glacier fluctuations occur. Finally, Battle (1960) suggested that the surficial glacier headwall boundary, marked by a randklu/t, rather than the bergschrund is the focal zone for weathering.…”

Section: Research Contextmentioning

confidence: 99%

“…On the basis of field measurements, Battle (1960) cast doubt on the prevailing bergschrund hypothesis of cirque formation . He suggested that open randklu/ts rather than closed, deep bergschrunds are focal zones for frost-shattering.…”

Section: Introductionmentioning

confidence: 99%

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Evidence for Headwall Weathering Zones, Boundary Glacier, Canadian Rocky Mountains

Gardner

1987

J. Glaciol.

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ABSTRACT. Temperature records from several randklu/t sites at the margins and headwall of Boundary Glacier (Iat. 52°12'N., long. 117°12'W.) in the Canadian Rocky Mountains are presented. These records indicate that during the ablation season a diurnal freeze-thaw air and rocksurface temperature regime occurs in a 2 m wide zone centred on the randklu/t lip. Deeper in the randklu/t , stable sub-zero conditions prevail whereas above the randklu/t an above-freezing temperature regime prevails. The freeze-thaw temperature regime, observed freezing of melt water and rain water on randklu/t rock surfaces, and copious in-situ loose weathering products on the head wall and marginal free faces suggest an active frost-shattering environment. Downslope migration of the randklu/t lip during the ablation season results in a migration of the freeze-thaw zone and thus a seasonal extension of the rock surface area exposed to the favorable weathering environment. Longer-term glacier fluctuations, with attendant thinning and thickening of the ice body, could result in large areas of marginal and headwall rock surfaces being exposed to the randklu/t weathering environment over long periods of time. The data and observations from Boundary Glacier support an idea, suggested by Battle (1960), that open and shallow randklu/ts, rather than closed and deep bergschrunds, are a focus of weathering at glacier margins and thus a potential factor in cirque development.

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supporting

confidence: 69%

Section: Research Contextmentioning

confidence: 99%

Section: Research Contextmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Evidence for Headwall Weathering Zones, Boundary Glacier, Canadian Rocky Mountains

Gardner

1987

J. Glaciol.

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“…Experimental results and field evidence, however, are contradictory. A number of workers consider that fast rates of freezing or 'Icelandic' cycles with high frequency, are most conducive to frost shattering (THOMAS, 1938;BATTLE, 1960 ;WIMAN, 1963 ;ARNI, 1966 ;POTTS, 1970 ;LAUTRI-DOU, 1978). Others, however, have found that the most rapid disintegration is associated with slow freezing, or with 'Siberian' cycles of low frequency (TABER, 1950;TRICART, 1956).…”

Section: Experimental Workmentioning

confidence: 99%

Freeze-thaw and shore platform development in Gaspé, Québec

Trenhaile

Rudakas

2011

gpq

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The role of freeze-thaw action in coastal environments, with particular reference to the formation of sub-horizontal shore platforms in Gaspé, Québec, was investigated experimentally. Rock cores and crushed rock samples were subjected to: two freeze-thaw cycles of twelve and twenty-four hour durations; fresh water and three artificial sea water solutions of about half, one and a half, and 'normal' salinity; and two drainage conditions representing rock pools and vertical well drained surfaces. These variables were selected to simulate some of the local environments which exist between the cliff top and low tide level in coastal Gaspé. Shales were the most susceptible to frost breakdown, followed in turn by argillites, calcisiltites and dolomitic silty argillites, and graywackes. Greatest disintegration tended to be associated with sea water solutions of about half-normal salinity. The data suggest that breakdown is greatest in the lower portions of the cliff. Freeze-thaw may produce the moat-like pools commonly found at the back of shore platforms. Although the process undoubtedly facilitates wave erosion of the platform and cliff, however, there is no evidence to suggest that it causes shore platforms to assume subhorizontal gradients.Le rôle de la gélifraction en milieu littoral, en particulier dans la formation des plates-formes subhorizontales en Gaspésie, a été étudié d’une façon expérimentale. Des carottes et des fragments de roc ont été soumis à des cycles gel-dégel de 12 et de 24 heures, les uns dans de l’eau ordinaire et les autres dans de l’eau de mer à salinité normale, à demi-salinité et à salinité et demie, dans des conditions d’humidité correspondant à celles des cuvettes rocheuses et des escarpements verticaux. Les conditions furent déterminées en regard des milieux naturels locaux prévalant dans la zone comprise entre le haut de la falaise et le niveau des basses mers, sur la côte nord de la Gaspésie. Les schistes se sont révélés les plus sensibles à la gélifraction; viennent ensuite dans l’ordre de plus grande sensibilité, les argilites, les calcshistes, les argilites dolomitiques et les grauwackes. La gélifraction maximale s’est produite dans une solution correspondant à la demi-salinité de l’eau de mer. Les résultats indiquent que la gélifraction est plus importante dans la partie inférieure de la falaise. Elle pourrait être à l’origine des cuvettes superficielles entaillant les plates-formes littorales. Bien que la gélifraction soit un processus favorisant l’érosion par les vagues des plates-formes et des falaises, rien ne permet d’affirmer qu’elle soit à l’origine des plates-formes littorales subhorizontales en Gaspé.Die Rolle der Gelifraktion in Kustengegenden, mit besonderem Hinweis auf die Entstehung von subhorizontalen Küstenplattformen in Gaspé, Québec, wurde im Experiment untersucht. Bohrungskerne und zermahlene Gesteinsproben wurden folgenden Kräften aus-gesetzt: zwei Gefrierund Auftauzyklen von zwölf und vierundzwanzig Stunden Dauer, Frischwasser, und drei künstliche Salzwasserlösunge...

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Rock Temperatures and Implications for Cold Region Weathering. I: New Data from Viking Valley, Alexander Island, Antarctica

Hall

1997

Permafrost Periglac. Process.

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A principal tenet of cold region weathering studies is that of temperature. Unfortunately, despite the appearance to the contrary, actual data are still sadly lacking in many instances. Here data are provided for the best part of two Antarctic winters plus, at two minute resolution, for one summer, from a variety of positions within a dry valley. The data clearly show the dangers of using air temperature as a surrogate for thermal conditions either at the rock surface or at depth in the rock. Although detailed rock moisture data are absent in this study, indirect evidence from both observation and non‐destructive ultrasonic testing shows that water is extremely limited during the period of freeze–thaw cycles. Thus, despite the occurrence of the thermal events no damage can result from frost action. Detailed data at two minute intervals show the importance of such high resolution observations. It is argued that without data acquisition at two minute or preferably one minute intervals, it is not possible to discern the weathering regime, including interpreting the freeze–thaw process. These data show that processes such as thermal stress fatigue/shock are possible and that rates of change of temperature ≥ 2°C min−1, as required for thermal shock, do occur. Measurements of taffoni size and occurrence, coupled with Schmidt hammer rebound values, show that the eastern aspect experiences the least weathering whilst the northern and western exposures have the greatest amount. This observation is in accord with separate findings of aspect‐controlled orientation of “cryoplanation” terraces at higher elevations. Some speculative suggestions for the cause of this aspect‐controlled weathering are given, the most important of which is that it is unlikely that freeze–thaw plays any significant role—a factor that underscores its qualitative presumption in cold regions and questions the origin and development of cryoplanation forms. Beyond anything else, this paper indicates the complexity of rock temperature regimes and suggests that it is the synergistic relationships between different weathering processes that are important. © 1997 John Wiley & Sons, Ltd.

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Temperature Observations in Bergschrunds and Their Relationship to Cirque Erosion

Cited by 41 publications

References 5 publications

Evidence for Headwall Weathering Zones, Boundary Glacier, Canadian Rocky Mountains

Evidence for Headwall Weathering Zones, Boundary Glacier, Canadian Rocky Mountains

Freeze-thaw and shore platform development in Gaspé, Québec

Rock Temperatures and Implications for Cold Region Weathering. I: New Data from Viking Valley, Alexander Island, Antarctica

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