This Is The World’s Deepest Hole

The Russians dug a nine-inch diameter hole 7.5 miles under the ground just to see what was there-until the Earth’s crust started melting their equipment.

The Cold War was a period of great competition between the USA and the USSR and we are reminded of this rivalry when looking back at the great space race. The race for a satellite (Sputnik), the first animal in orbit (a dog named Laika), and the first man in orbit (Cosmonaut Yuri Gagarin) all were won by the USSR, and then the US won the race to put a human on the moon. However, the most interesting race wasn’t one that went away from the earth—it was a journey towards the centre of it (but without Brendan Fraser). The battle wasn’t just based on ego though—in many ways we know more about the universe around us than we do the world beneath us. This is why earth scientists wanted to dig deep, and uncover the secrets hidden beneath our feet.

The US kicked off the race in 1961 with Project Mohole, which aimed at reaching the Mohorovičić discontinuity, which is the place where the Earth’s crust meets the mantle. Over the next five years, the team at Project Mohole succeeded in digging 601 feet (183 meters) down into the earth’s crust. The impressive part is that they were doing so through 11,700 feet (3,566 meters) of ocean water. Rising costs led to the project being stopped as the US Congress eventually caught on to the fact that they were almost literally throwing money down a hole.

In 1970, the USSR looked at the progress the US had made on Project Mohole and said, “Hold my beer Comrade”. The Kola Superdeep Borehole was started on May 24, 1970 in the Pechengsky District of Russia and the drilling finally stopped the better part of three decades later. The borehole is a series of drill shafts, with the deepest one being 9 inches wide and 40,502 feet (12,345 meters) below the surface—both the deepest artificial hole dug in the earth and the longest drill shaft dug (at that time). The digging ended in 1994 due to the heat; at that depth, temperatures reached 180 degrees Celsius (356 degrees Fahrenheit), causing the drill equipment to malfunction and break down.

In the process of digging the borehole, the Kola Superdeep team didn’t just break all records for deep drilling, they also made a number of amazing scientific discoveries including microscopic fossilized plankton that was more than two billion years old; a lack of transition between granite and basalt (known as the “Conrad discontinuity”); vast quantities of hydrogen gas; and water that had formed deep in the earth and been trapped beneath layers of impenetrable rock.

In subsequent years, longer drill shafts have been dug, but the Kola Superdeep Borehole remains the deepest in the earth’s crust. While it is without a doubt one of humanity’s most amazing accomplishments, Kola’s fate ended quietly. In 2006 the funding eventually ran out, and the drill equipment was removed. The site was officially abandoned in 2008 and the deepest artificial hole on earth was covered with a type of small manhole cover that might not look out of place on a city street.

The goal of drilling to the earth’s mantle hasn’t been forgotten. While the Kola Superdeep Borehole has been capped, a Japanese team is planning another drill effort to reach the mantle that is set to start around 2030. The future might hold more secrets about the great unknown world right in our own backyard.

Did You Know?

  1. The Kola Superdeep Borehole sits in the Pechengsky District of Russia and was started on May 24 1970.
  2. The borehole actually is a series of holes, all branching off from a central hole.
  3. The deepest portion of the hole, while only nine inches in diameter, is 40,230 feet (12,262 meters) deep.
  4. The hole remains the deepest borehole, despite the 40,502-foot-long (12,345 meter) Skhalin-I Odupto OP-11 well, dug in Russia in 2011.
  5. Scientists were stunned by the discovery of fossilized plankton, single-celled organisms two billion years old.
  6. They were also baffled by the lack of transition between granite to basalt, called the “Conrad discontinuity.”
  7. Another surprise: water! It’s believed to come from tremendous pressure forcing out hydrogen and oxygen atoms.
  8. The Kola Superdeep Borehole was capped and abandoned in 2008, its top marked with an average-looking manhole.
  9. Next on the horizon: Japan’s attempt to dig even deeper, aiming for the Earth’s mantle, 6 miles (10 kilometers) under the sea floor.
  10. Drilling is expected to start by 2030 but the location of the project is undetermined.