The bergs circle the continent like ice debris in the rings of Saturn.
The perimeter of ice varies with the ebb and flow of the circumpolar current and the general climate. The pack ice remains frozen much of the year, retarding the movement of trapped bergs. At other times, the perimeter of the circumpolar current swells outward and icebergs range widely over the Southern Ocean. Occasionally, very large bergs encounter favorable circumstances that fling them outward well beyond the Antarctic convergence altogether. Bergs have been sighted from South Africa after being hurled out of the Weddell Sea gyre, as well as off the coast of Peru, embedded in the cold Humboldt current.
Ocean swells cause the berg to oscillate (if the ice is rigid) or vibrate (if the ice is elastic). Some of the movement is linear, making the berg bob up and down like a glacial cork. Some is angular, encouraging the berg to rock back and forth. Both oscillations and vibrations, however, set up stress fields within the ice. How the berg responds depends on the wavelength of the swell, the thickness of the berg, and the presence of internal fissures. Very large, thick bergs absorb the vibrations with little effect; the entire berg may slowly bob or rock but there will be little internal deformation. Thinner bergs or ice shelves may simply bend elastically without rupture. But under the proper circumstances—if the wavelength of the swell and the ratio of thickness to width in the berg are in the right proportion—rupture may occur. Should the berg vibrate near its natural frequency, it will shake into large pieces. Flexure and fatigue failure seem to be important processes in the calving of bergs from shelves. For large bergs, especially those with residual cracks that may propagate under the proper stresses, the process of stress failure continues to operate.
The berg even rotates. One rotation is slight but constant, the product of a sheath of meltwater that surrounds the berg as it ablates. This liberated freshwater has a lower density than the surrounding seawater and accordingly it rises. At lower levels, the pressure differential is sufficient to have an impact. Seawater enters the sheath, but under the impress of the Coriolis force, the flow deflects to the left; the berg spins. More dramatic are those rotations from top to bottom of the berg. The density profile of an Antarctic iceberg shows a lighter top of snow and firn riding above a much denser ice substratum. But as the top erodes, as side disintegration results from thermal ablation and the mechanical response to the new stress field, and as the bottom reshapes from crevasse erosion and thermal convection along the sides, the berg can become unstable. The top may roll over. The critical variable seems to be the ratio of berg length to width. For a berg 200 meters thick, the minimum width should be 220 meters to prevent roll instability.
Only occasionally does the process get this far. More common is an adjustment of shape to density that causes the berg to tilt perpetually one way and then another. The berg will list more often than it will capsize. The lighter snow and firn are particularly susceptible to wave erosion, brine infiltration, meltwater percolation. A drifting berg will experience a wave-cut underwater terrace to its rear, and the removal of this material causes the rear to rise and the front to lower. This tilting affects the way the berg intercepts current and wind, and the berg rotates. The newly exposed top will, in turn, be subjected to more vigorous wave erosion. In theory the process can continue indefinitely. But before an ice peneplain can result, the berg will most likely dissolve into a kaleidoscope of exotic forms, a happy entropy of particles and motions.
A Plastic Art: The Esthetics of Icebergs
Ice is a plastic art. No other object more fully challenges the theory and practice of esthetics. The journey of the ice from crystal to berg is not simply a story of matter and motion: it is an esthetic journey of the first magnitude. And of all Antarctic ices the berg is the most artful. It contains all the stuff, the shapes, and the motions of other Antarctic ice, yet it combines them uniquely and it mounts them, like a set jewel, in an environment that enhances their effects. To James Eights, first naturalist to land on the continent, the icebergs were “in a peculiar manner, adapted to create feelings of awe and admiration in the bosom of the beholder, not alone from the majesty of their size, but likewise, by the variety of the forms and ever changing hues that they assume.”1 To veteran Antarctic explorer and scholar Frank Debenham, the bergs were “of all the natural features of the Antarctic the most strange and impressive.”2
No other ice mass displays such a range of sculptural forms. Though the largest bergs are impressive by virtue of their sheer monotonous size, the smaller bergs take the shapes of white earthscapes. Erosion weathers them and instabilities tilt them into exotic spires, castellated facades, and ice sphinxes. Others assume the lumpish mass and abstract blocky forms of modernist sculpture. The ice terrane as a whole presents a sculpture garden of kinetic art.
No other ice mass plays with light so effectively. The berg’s appearance changes constantly, with the orientation of berg to sun and to the surrounding environs of sea ice, fog, and cloud. The berg’s translucent blue and green ices, its dull luminous firn, and its brilliant reflective snow make the berg into a virtual prism. In purest forms, glacial ice glows with a bluish tint. Occasionally absorbing impurities or acquiring glasslike properties of sheared ice, it takes on a greenish lustre, like dull jade. In still other circumstances, its bottom strata are charged with rocky, brownish debris which may rise to the surface should the berg overturn. With bands of whitish bubbles swirling through it and fresh snow lacing its fabric of fractures, the blue ice resembles a patch of sky streaked with ice clouds—a bizarre reification of its source in the polar plateau.
Immersed in direct sunlight, the snowy berg hurls the light back with dazzling intensity. The berg sparkles amid its surroundings, an undifferentiated, unearthly presence. Nothing of the berg itself is revealed. Better understanding requires more subtle lights. In oblique sunlight the berg appears like ivory, dull and opaque. In fog the berg is highlighted by shadow, a grey outline amidst a whitish mist. In stronger sunlight, it emits a ghostly translucence, becoming a kind of ice opal. Under an overcast sky, white light cannot penetrate. But other wavelengths act on the ice and snow to produce an eerie, bluish-white phosphorescence, a luminous glow that accents the internal structure of the berg and contrasts weirdly with the ivory-colored sea ice and the navy-blue sea.
The berg synopsizes the esthetics as much as the glaciology and geography of Antarctica. Yet it does so by virtue of a paradox. The simplicity of The Ice is staggering, and embedded within the ice field an ice mass is flat, opaque, almost featureless. It only reflects those perceptions brought to it, or refracts that information extracted from it. The ice field from which the berg emerges is an esthetic sink. The character of The Ice is derived and its brilliance secondary. The Ice adds by removing, transforms without creating, informs by obscuring. Its meaning does not reside within Antarctica, awaiting revelation, but derives from the illumination brought to it from outside. Ice does not merely reflect mind: it absorbs it. The more it absorbs, the larger it becomes; the more light brought to it, the more powerful its reflection.
The special properties and meaning of the berg both as a natural phenomenon and as an esthetic object derive instead from its surroundings, from the fact that this ice mass has been removed from its confining ice field. There are contrasts—ice and ocean, ice and the esthetic canons brought to bear on it. The berg is the most revealing, and most pleasing, of Antarctic ices because it is the least typical. It is the most intellectually and emotionally accessible of Antarctic ices because it is the most complex. In this, too, the berg symbolizes Antarctica—the least known and least knowable of continents, not because it is the most complex but because it is the most simple. This is a looking-glass landscape where things may be less, not more, than they seem.
Its simplicity is stupefying. Contrasts, comparisons, analogies, metaphors—all vanish before the pure immensity of the ice monolith. Antarctica mocks the belief that the essence of art—or of life or of civilization—is simplicity. This is a minimalist landscape that requires a high order of esthetics to be appreciated. Where the ice is ensconced within ice within more ice, art finds itself without information; the senses are stripped; perception vanishes into a white nirvana. At its source, The Ice is a world in a state that approximates frozen invariance. The Ice
