In 1970, Russian geologists drilled a nine-inch wide hole into the Kola Peninsula’s Baltic Shield — a part of Earth’s crust with rock well over a billion years old — and began digging as deep as they could go.
After 20 years, what was called the Kola Superdeep Borehole reached a maximum depth of 40,230 feet, or nearly 7.62 miles, into Earth’s surface. Drilling stopped in 1992 because of equipment limitations with high heat, but the Kola Superdeep remains the deepest human-made hole in history.
And yet, amazingly, the project’s incredible depth was just 0.2 percent of the distance to Earth’s core, and not even halfway to what scientists refer to as the “upper mantle.” This particular section of our planet — comprised of two subsections known as the lithosphere and the asthenosphere — are where tectonic plates shift, causing earthquakes and volcanic eruptions, as well as the movement of the continents and the forming of mountains.
In essence, it’s where hot stuff happens.
