Antarctica is not only a land of ice — sometimes, in some places, it seems to be a land of gigantic ice cubes. But why? How this large, rectangular formations in the inhuman, irregular landscape of the southern continent?
The image above, with the title “Icy sugar,” was taken in Antarctica in 1995, on the English Coast, to the southern Antarctic Peninsula. The British Antarctic Survey recently scanned the photo, which was initially shot on Kodachrome 64 slidefilm, and in 2017, the highest prize in The Royal Society’s annual science photography contest. The “unusual bi-directional crevassing’, The Royal Society, explained in a caption, “if an ice cap … stretched in two directions across an underlying increase.”
But that’s not all that’s going on in that photo, according to Ted Scambos, a glaciologist and a scientist for the National Snow & Ice Data Center science team. [See also the Winners of the Royal Society photo contest]
The photo seems to represent an area of “fast-flowing and ice,” Scambos wrote in an email to Live Science.
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Although Antarctica’s enormous masses of ice can firmly grasp the eyes of man, the reality is that they are in constant motion, flowing and bumping and grinding against each other. That movement causes patterns to appear — not by carving but instead of a long period of pulling.
“A massive sheet of flowing ice starts to float,” Scambos wrote, “and in the first instance, because it is very thick, it spreads laterally [side], making deep along-flow valleys. Later, with more flow, the ice begins to stretch out in the length and the area of snow breaks perpendicular to the first drop.”
In other words, if the ice spreads and thins, it cracks. At first, the cracks parallel to the ice of the forward movement, creating a series of horizontal slits. Later, another series of cracks appear perpendicular to the direction of the ice flow, the filling in of the peculiarly regular grid, Scambos said.
The picture provides clues that can help researchers and Scambos think that the direction in which the ice flowed.
“Note that the troughs that are more perpendicular to the planes are a bit older, more full of snow — I think that they are parallel to the direction of the flow,” Scambos wrote.
Because these segments are all longer, more snowstorms have passed over them, filling them.
“The sharper cuts to make the blocks, more in the direction of the plane on the flight, are younger, and mark a transition somewhere just upstream to more advanced conditions,” Scambos wrote.
In other words, the ice was probably flowing along the paths of the shallower slices, and the deeper, sharper slices seemed more recent. The Antarctic ice, solid as it looks, hides literal gigatons of mysterious forces and movements.
Originally published on Live Science.