The Strange Story of the World’s Deepest Hole
Do you have any idea of how deep the world’s deepest hole is? Most
likely not. The deepest hole in the world is the Kola Superdeep
Borehole, which is estimated at 40,230 ft (12,232 meters) deep into the
earth’s crust. This hole on the Kola Peninsula is the outcome of a
scientific drilling project carried out by the defunct Soviet Union,
aimed at drilling to the greatest achievable depth into the earth’s
crust. The drilling helped to shed light on some topics that had
hitherto been shrouded in mystery.
Motivation for Drilling
The Kola Superdeep Borehole is considered a product of the Cold War
between the former Soviet Union and the United States. Back in 1957,
America had embarked on a project called Project Mohole aimed at
drilling through the shallow crust below the Pacific Ocean, off the
coast of Mexico. But the drilling project was abandoned halfway in 1966
due to lack of funding. Seeing the failure of its bitter rival, the
Soviet Union was determined to succeed where the US had falter by
drilling to the core of the earth’s crust, or as close as possible.
Drilling of the Kola Superdeep Borehole
Drilling began in 1970 with the target depth set at 15,000 meters, or
49,000 ft. The target was deemed achievable by 1993. The drilling of
the Kola Superdeep Borehole commenced with an Uralmash-4E drilling rig
before graduating to the Uralmash-15000 series rig. By June 1979, the
world-record depth level of 9,583 meters (31,440 ft) which was
associated to the Bertha Rogers hole in Oklahoma, US had been surpassed.
There was a one-year hiatus in drilling activity after the 12,000-meter
mark was breached in 1983. But the researchers were not able to add
more than 262 meters before the project was stopped in 1994.
A very high temperature level of 356 degrees Fahrenheit was
experienced at the maximum depth — a level way higher that the 212
degrees Fahrenheit that had been predicted. The high temperature levels
at the depths made it impossible for the drill bit to function long
enough to reach the previously-set target. But it was not until 2005
before the project was officially shut down.
Findings from the Drilling
The drilling of the Kola Superdeep Borehole helped to shed light on
several topics that had not gone beyond the level of theories before
drilling commenced. Among the findings from this scientific research is
the lack of transition from granite to basalt at about 6-7 km below the
surface of the earth. Before then, scientists had found out a
discontinuity was present at this depth based on information obtained
through seismic waves. They assumed the discontinuity was as a result of
transition in rock types. But this drilling research disproved that
assumption. It was discovered that the discontinuity was as a result of a
metamorphic transformation in granite at the depth and not because of a
change in the type of the rock present.
Large amount of hydrogen was also surprisingly discovered by the
drillers, and the quantity was way beyond what could have been expected
at the depth. In addition, free water was unexpectedly found and this is
believed to have been formed from a combination of hydrogen and oxygen
atoms from the surrounding rock. The impermeability of the layer of rock
above made it impossible for the water to come to the surface.
There were some other findings made in the drilling of the Kola
Superdeep Borehole, including the surprising discovery of microscopic
plankton fossils in rocks whose ages are put at more than two billion
years.
You can join the numerous people paying visits to the site of this
impressive scientific drilling project. The only thing is that you
should not expect to be able to look into this bottomless hole, as its
top has been welded shut with strong metal. But you can check rock
samples extracted from the hole at the Kola Core Repository in
Zapolyarny.
Photo source: wikipedia.org
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