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

• Published in: Journal of Glaciology
• Main Author: Reid, John R.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 1964
• Subjects: Earth-Surface Processes; Antarctic; Ross Ice Shelf; Bay of Whales; Antarc*; Antarctica; Ice Shelf; Journal of Glaciology
• Online Access: http://dx.doi.org/10.1017/s002214300002877x; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S002214300002877X

Abstract 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.