Siberia: the strange satellite images of NASA that amaze experts

A series of satellite images taken by the NASA in the north of the region Siberia, Russia, shows a very particular landscape. The ground, seen from space, exposes polygonal patterns and variations of dark and light wavy stripes. The uniqueness presented by the territory of this sector of the Siberian Arctic puzzles scientists, who have tried to explain the phenomenon.

The photos were taken by satellite Landsat 8 on both banks of the river Bay, in northeast Siberia. The recording was made over several years and the landscape was captured at different seasons of the year. This week, NASA’s Earth Observatory page published several of these photographs, which drew attention to their peculiar topography.

Scientists are not entirely sure why these different hue patterns on Earth become even more intense in images taken in winter. Some find the explanation written on the frozen ground.

This region of the central Siberian plateau, located in the Arctic, is 90% of the year covered with permafrost – frozen ground -, as expressed by the NASA, which thaws at short intervals. When patches of soil cyclically thaw and refreeze, they adopt strange circular or striped patterns that are known as “patterned floors,” according to what scientists reported in a January 2003 article in the Science journal.

However, this explanation does not fully capture the phenomenon, as other examples of “patterned” floors tend to show designs with stripes smaller than those seen in the siberian soil.

For the geomorphologistsMeanwhile, the nature of the soil offers another explanation for the lines of different shades. In such cold regions, a type of phenomenon known as gelisol. That is, a soil with permafrost in the top two meters, in which dark and light layers are normally distinguished based on the amount of organic or mineral matter and their sediment content.

When the ground freezes and melts, the layers break up and mix vertically in a process called “cryoturbation ”. The persistent freeze-thaw action throughout the seasons can cause the layers to line up in a striped pattern. Different types of vegetation tundra (lichens, low shrubs and moss) may preferentially grow in these layers of Gelisol, accentuating the stripes seen from above. But this hypothesis has not been tested on a large scale.

Another possible reason for this phenomenon is erosion. Thomas crafford, geologist of United States Geological Survey, expressed on the observatory page of the NASA that the stripes resemble a pattern of sedimentary rock known to experts as “Geology of the cake layers”.

These patterns occur when the snow is melting or the rain is falling, chip and dump pieces of sedimentary rock in piles. The process can reveal patches of sediment that look like strips of a multi-layered cake, according to Crafford, with darker stripes representing stiffer areas and lighter stripes reflecting flatter areas.

According to what satellite images show, this type of sedimentary stratification it stands out more in winter, when the snow rests on the flattest areas, making this part of the landscape even clearer.

In areas that approach the river, the pattern gradually fades. “Sometimes the sediment accumulates in more uniform piles along the banks, after millions of years of erosion,” he said. Crafford.

The pattern fades to the banks, where sediment accumulates in more even piles along the banks after millions of years of erosion, he added. Crafford.

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