Its hard to imagine that under this small metal cap lies the worlds deepest borehole.
The crust is the earths outermost layer.
Underneath the mantle is believed to lie a solid core of iron.
The first attempt to drill through the crust was undertaken by the United States in the early 1960s.
It was chosen to drill through the sea floor because the earths crust was thinner under the oceans.
The hole reached only 183 meters before the government pulled funding and the project was abandoned in 1966.
Five years later, the Soviets decided to take a crack at the crust.
The drilling of Kola Superdeep Borehole.
Image taken in 1974.
In 1983, the drill passed the 12,000 meters mark and Soviet scientists erupted in jubilation.
The rusty drill bit used to drill to the unprecedented depth was displayed to those who visited.
A postage stamp with image of the site and special cancellation envelopes were quickly released.
While everyone was busy celebrating, the drilllay uncared and unrepaired.
Consequently, when drilling commenced a year later, a 5-km-section of the drill string twisted and broke off.
After all attempts to recover the broken section failed, drilling was restarted from a depth of 7 km.
It took another five years to reach its final depth of 12,262 meters.
Scientists expected to find the so-called boundary of granite to basalt at a depth of about 7 km.
They also found microscopicplankton fossilsat depths of 6 kilometers.
Another unexpected discovery was a large quantity of hydrogen gas.
The mud that flowed out of the hole was described as “boiling” with hydrogen.
Another ultra-deep drilling project commenced in Bavaria in 1990 where German engineers drilled to a depth 9,101 meters.
Core sample extracted from Kola Superdeep Borehole, 1980s.
Photo credit: Ivanovic Vladimir Khmelinsky
Core sample lifting and extracting at Kola Superdeep Borehole, 1980s.
Photo credit: Ivanovic Vladimir Khmelinsky
The site today.
Photo credit:Alexei Zaitsev
Photo credit:Bigest/Wikimedia
Photo credit:Rakot13/Wikimedia
Photo credit:Alexander Egortsev
