The Growth of the Glacier Crystal Some Further Notes

Seligman, G.

doi:10.1017/s0022143000012582

Cited by 8 publications

(4 citation statements)

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“…It is well established that for polycrystalline ice under no (or very low) stress, the crystal size increases with time at a rate dependent on the temperature (Stephenson, 1967; Gow, 1969, 1970; Budd, 1972; Gow and Williamson, 1976, for Antarctic ice; Herron, 1982, for Greenland ice; Seligman, 1949, 1950; Kamb, 1964, for laboratory observations). Results from deep ice cores collected from Byrd Station, Antarctica (Gow and Williamson, 1976), Dome C, Antarctica (Duval and Lorius, 1980), Vostok, Antarctica (Korotkevich and others, 1978), Law Dome, Antarctica (Young and others, 1985) and Camp Century, Greenland (Herron, 1982) indicate that the increase in crystal size with time and depth can be disturbed by other factors.…”

Section: Introductionmentioning

confidence: 99%

The steady-state crystal size of deforming ice

Jacka

1994

Ann. Glaciol.

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Previous studies have established that, together with the development of a preferred crystal-orientation fabric in ice undergoing creep deformation to high strains, there also develops a tertiary equilibrium crystal size, i.e. the crystal size, rather than affecting the creep rate, is a result of the deformation to large strains.Equilibrium crystal size is considered here as a "balance" between crystal growth with time as a function of temperature and crystal change as a result of temperaturedependent deformation. The temperature effects in these two processes (Arrhenius relation) are similar and consideration of the activation energies for the two processes indicates that it may be appropriate to cancel them, yielding a dependence of equilibrium crystal size on stress alone. The results from laboratory experiments of steady-state crystal size plotted as a function of stress support the above proposition.The possibility of using the relationships between steady-state crystal size and deviatoric stress as a polar ice-mass piezometer is discussed.

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Section: Introductionmentioning

confidence: 99%

The steady-state crystal size of deforming ice

Jacka

1994

Ann. Glaciol.

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“…3, p. 267 16 ) Seligman’s tentative hypothesis is thus apparently inconsistent with Perutz’s view that increase of average crystal size is the invariable result of strain. The two views may perhaps be reconciled by taking into consideration the increase in crystal size that has been observed by Seligman on the upper surfaces of ice-tables carved out in tunnels in the Upper and Lower Grindelwald Glaciers; Seligman attributes the increase in grain-size to relief of pressure (Seligman, p. 380 17 ). We have seen that the grain-size of quartz close to the Moine Thrust was reduced as the result of increasing shearing stress.…”

Section: Petrological Significance Of the Results Of Research On mentioning

confidence: 99%

“…In the deeper layers of glacier ice (investigated only in a tunnel in the snout of the Upper Grindelwald Glacier) Seligman found assemblages of abnormally small crystals. After discussing various possibilities, he has suggested tentatively that they may be due to recrystallization under abnormally great stresses caused by an ice fall not far “up-stream” (Seligman 1949, p. 264 16 ; 1950, p. 379–80 17 ). In this suggestion he was influenced by Deeley and Fletcher who, some fifty years ago, attributed to shearing (and in part to fracture) the formation of many small elongated ice crystals observed in tunnels in the Upper Grindelwald and other glaciers (Deeley and Fletcher, p. 155–57 5 ).…”

Section: Alpine Research On Glacier Icementioning

confidence: 99%

Ice Crystals in Glaciers Compared with Quartz Crystals in Dynamically MetaMorphosed Sandstones

MacGregor

1951

J. Glaciol.

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ABSTRACT. Attention is drawn to resemblances berween two contrasted styles of mosaic crystallization-tessellate and equigranular as compared with irregularly interlocking (sutured) and inequigranular-that characterize ice in alpine glaciers and quartz in dynamically metamorphosed sands tones of the Moinian area of the northern Scottish Highlands. It is suggested that in both environments the contrasted types of mosaic are due to crystallization under conditions of shearing stress that were respectively minimal and maximal. Similarities are also pointed out between the orientation of the principal crystallographic axes of crystals in ice subjected to shearing stress, and the "girdle" arrangement of the principal crystallographic axes of quartz in Moinian metamorphic sands tones.ZUSAMMENFASSUNG. Es wird auf die Aehnlichkeit zwischen zwei typischen Arten der mosaikformigen Kristallisation hingewiesen-wiirfelfOrmig und gleichkornig gegeniiber ungleichmassig verzahnt und ungleichkornigwodurch einerseits das Eis der alpinen Gletscher u nd andrerseits der Quarz in dynamisch metamorphen Sandsteinen der Moinian Formation des n ordlichen schottischen Hochlandes charakterisiert werden. Es wird vermutet, dass in beiden Fallen der festgesteIlte Typus des Mosaiks bedingt sei durch eine unter dem Einfluss von minimalen bzw. maximalen Scherspannungen erfolgte KristaIlisation. Ferner wird die Verwandtschaft zwischen der Orientierung der kristallographischen Hauptaxen d es durch Scherspannungen beanspruchten Eises und der umgiirtenden Anordnung der kristaIIographischen Axen des Quarzes in metamorphen Sandsteinen der Moine Formation hervorgehoben.

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“…Release of stress will cause an increase in crystal size. Seligman (1950, p. 380–81) observed an eight-fold increase in the crystal size in blocks that had been cut from ice tunnels in Switzerland and left standing for decoration. He attributed this increase to the release of stress, but he also admitted that the better circulation of air around the blocks might have favored the growth.…”

Section: Factors Of Recrystallizationmentioning

confidence: 99%

Structural Glaciology of an Ice Layer in a Firn Fold, Ross Ice Shelf, Antarctica: Ice Grain Analysis

Reid

1964

J. Glaciol.

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A highly deformed area in the Ross Ice Shelf near the Bay of Whales was studied during the 1958–59 Antarctic summer season. A series of snow-firn folds up to 8 m. high and with a wavelength of approximately 100 m. occurs here. Along one of these folds, a unique ice layer formed during the 1952–53 season through refreezing of melt water. From sites along this layer approximately 2,300 ice grains were measured using the root mean square method with the least circle diameter. The data obtained indicate the following: The mean diameter of the ice grains ranges from 4.5 mm. in the ice from the crest of the anticline to 2.5 mm. in the zone of maximum shear stress and/or in sections having a high air bubble content.The large diameter of the ice grains at the crest is attributed to greater solar radiation resulting from their proximity to the 1958–59 snow surface, and because they are near the surface of the exposed crevasse wall.The area of maximum shear stress, which is represented by small ice grains and the presence of secondary folds, is located almost halfway between the crest and the trough.Grains in the trough are larger than those in the shear zone because of less stress, and smaller than those at the crest because of deeper burial and the presence of a crevasse bridge which eliminates all direct radiation here.The growth of the ice grains is therefore controlled by temperature, stress and impurities.

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The Growth of the Glacier Crystal Some Further Notes

Cited by 8 publications

References 1 publication

The steady-state crystal size of deforming ice

The steady-state crystal size of deforming ice

Ice Crystals in Glaciers Compared with Quartz Crystals in Dynamically MetaMorphosed Sandstones

Structural Glaciology of an Ice Layer in a Firn Fold, Ross Ice Shelf, Antarctica: Ice Grain Analysis

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