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Satellite images of northern Siberia released by NASA leave scientists perplexed


The geological mystery recorded in the photos has given rise to several scientific hypotheses.

A series of satellite photos of a arctic zone Russia has raised questions among NASA scientists.

This week, researchers from the US aerospace agency published images of an area in northeastern Siberia, recorded by the satellite, on the Earth Observatory website. Landsat 8 over the course of several years.

In these photos, the terrain on both sides of the Marja River presents a sequence of alternating stripes, dark and light, more compact in steep slopes and wider where the slope is gentle, until it disappears towards the edges.

This peculiarity is visible in all seasons of the year, although it is more marked in winter, when the snow increases the contrast.

Explanations

Some experts have offered NASA various explanations for this phenomenon. One of the hypotheses points to the fact that this area of ​​the central Siberian plateau is located within the Arctic circle and, therefore, 90% of the time is covered by permafrost, which sometimes melts for short periods. It is known that tracts of soil that freeze, melt and refreeze can form strange patterns polygonal, circular and hatched.

However, elsewhere those patterns tend to be smaller in scale than the stripes recorded in Siberia.

Researchers from geomorphology offer another explanation: in such cold regions, the land can become ‘gelisol’, a soil with permafrost in the upper two meters, in which the dark and light layers are normally distinguished based on the prevalence of organic or mineral matter and their sediment content.

As the soil freezes and melts, the layers they open and mix vertically. By repeating these cycles over periods of time, the layers can line up and form striped patterns. Various types of vegetation of the tundra can grow on them, accentuating the stripes seen from space. This hypothesis, however, has not been tested on a large scale.

Thomas Crafford, a researcher with the US Geological Survey, says the stripes reflect a pattern of sedimentary rocks known as ‘puff pastry geology’, in which these rocky layers have been exposed and are dissected by erosion. As snowmelt or rain drifts down the slope, chunks of rock they take off and slide into the ravines. Such erosion can cause staggered patterns, seen as lightning bolts from space.

In winter, the flat parts are covered with snow, becoming lighter, while the dark areas correspond to slopes. The fading of the striped pattern at the edges would be due to the amontonamiento sedimentary caused by erosion that has lasted for millions of years.

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