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Natural Cataclysms Predict Glaciations

11.01.2002


Not only geologists are interested in giant canyons of Kursk Magnetic Anomaly, but also soil scientists. There is very convenient place to watch old soils, which earlier were on the surface. As the canyons grew wider, details of ancient landscapes and their changes appear. While studying one of those canyons, Svetlana Sycheva from the Institute of Geography Russian Academy of Sciences has found that earlier there was a system of large ravines, now buried under a thick layer of sediments.



It was found that the landscape and soil changes do not occur randomly, in fact, they are strictly periodic - the glacier epochs take turns with interglacial ones. The old gully, which Sycheva was studying, formed about 130 thousand years ago, at the end of the Dneprov icing, when there was a sudden, even catastrophic climate change. Dry and cold weather, which caused permafrost in Central Russia, was changed by wet and warm Mikulin interglacial period. When sudden soil defrost came and too much water flowed in because of glacier thawing, soils began to cover all the ravines, even large ones.

As the climate settled and warming came, the newly formed earth relief acquired vegetation and soils developed. The gully was `resting`, being covered with forests. That lasted for 15 thousand years. At the end of Mikulin interglacial period, a series of cataclysms happened, because of frequent changes of warmth and frost. After a long drought, severe fire broke out and destroyed forests in gullies. Without vegetation, the slopes destructed and fertile soils were washed out. By the middle of Valday icing (50-40 thousand years ago), the gully was covered with sediments from water flows.


Sycheva believes that the history of old gullies and ravines is the perfect model of changes between glacial and interglacial epochs. Most natural cataclysms - long droughts, floods, early frosts - happen in these transition periods. Forest fires in interglacial periods are not so destructive, they clean the landscape and promote flora renewal. On the contrary, the fires in the beginning of glacial periods are dangerous to soils - they freeze faster, erode, become salted. So the soils, which are fertile now, may become unusable because of rather natural reasons.

We are living just in this time - the end of the Holocene interglacial period, which started about 10 thousand years after Valday icing. The scientists explain the increase in the number of catastrophes as a result of natural factors. For the next 3-4 thousand years there may be severe climate changes - from hard droughts to sudden chills, with general tendency to cold.

Tatiana Pitchugina | alphagalileo

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