The Patomskiy Crater

Located on a slope of Patomskiy upland in Irkutsk, Siberia, about 360 km from the district center Bodaibo, Patomskiy Crater is a crater made of shattered calcareous blocks. The mysterious crater was named Patomskiy after a nearby river and first discovered in 1949 by Vadim Kolpakov, a geologist. At that time, while on expedition, Kolpakov traveled deep into almost uncharted territory, the local Yakut people warned him not to go on explaining there was an evil place deep in the woods that even the animals avoided. They called it the “Fire Eagle Nest” and claimed that people would simply disappear without a trace. The origin of the Patomskiy crater has baffled scientists for decades and theories for its existence have ranged from a nuclear blast to a secret gulag mine and even a meteorite strike.

It is a large mound of limestone with a diameter of about 160 meters and a height of about 40 m, while the crest's diameter is 76 m. The cone's crown is formed like a ring shaft. The depth of the inner circle ditch is around 12 m. The volume of the crater is estimated as 230-250 thousand cubic meters. 

Theories that the crater is a giant slagheap have been thrown out as there were not enough people living nearby when the crater is thought to have formed to create such a pile. And there were never labour camps or gulags in the region. Half a tonne of samples were taken from the site and removed by helicopter on 2013.

The Patomskiy Crater

The samples led scientists to dismiss ideas of a uranium ore explosion as the background radiation at the site is low and no uranium has been found nearby either. This left them with two main theories – one of a volcano and another of a meteorite. However, there aren't any meteoritic material to be found and the area is not thought to be volcanic.

In fact there are no volcanoes within thousands of kilometres of the Patomskiy crater and it also seems to be relatively new. Kolpakov estimated it as around 250 years old, a figure supported by later studies of nearby tree growth. Interestingly, the crater is seemed ‘alive’ because its shape changes constantly - by rising and falling - and the trees also seemed to have undergone a period of accelerated growth similar to that seen in the forests around Chernobyl.

Many even think that there is a UFO hidden underneath the crater. In 2005, an expedition was launched in the hopes of finding some answers—but then tragedy struck. The leader of the expedition died of a heart attack just a few kilometers away from the site. The locals were convinced it was the “evil” crater that led to his death.

Sources:
http://en.wikipedia.org/wiki/Patomskiy_crater

http://beforeitsnews.com/strange/2014/06/10-strange-mysteries-that-remain-unsolved-part-1-2456932.html

http://www.dailymail.co.uk/sciencetech/article-2553841/Siberian-eagles-nest-continues-baffle-scientists-Theories-250-year-old-mound-formed-range-meteorite-strike-nuclear-blast.html

Pic Source:
http://i.dailymail.co.uk/i/pix/2014/02/07/article-2553841-1B42F17600000578-464_634x422.jpg