Kola Superdeep Borehole16 Jul 2023 21:17
The Kola Superdeep Borehole (Russian: Кольская сверхглубокая скважина, romanized: Kol'skaya sverkhglubokaya skvazhina) SG-3[a] is the result of a scientific drilling project of the Soviet Union in the Pechengsky District, near the Russian border with Norway, on the Kola Peninsula. The project attempted to drill as deep as possible into the Earth's crust.
Drilling began on 24 May 1970 using the Uralmash-4E, and later the Uralmash-15000 series drilling rig, and it became the deepest manmade hole in history in 1979.
The Kola Superdeep Borehole penetrated about a third of the way through the Baltic Shield continental crust, estimated to be around 35 kilometres (22 mi) deep, reaching Archean rocks at the bottom.
Microscopic plankton fossils were found six kilometres (3.7 mi) below the surface.
Another unexpected discovery was a large quantity of hydrogen gas. The drilling mud that flowed out of the hole was described as "boiling" with hydrogen.