The Kora Borehole got to 12,262 metres deep, and was stopped due to a lack of funds.[1] """ Drilling penetrated about a third of the way through the Baltic Shi

The Kora Borehole got to 12,262 metres deep, and was stopped due to a lack of funds.[1] """ Drilling penetrated about a third of the way through the Baltic Shield of the continental crust, estimated to be around 35 kilometres (22 mi) deep, reaching Archean rocks at the bottom.[13] Numerous unexpected geophysical discoveries were made: During the drilling process, the expected basaltic layers at 7 kilometres (4.3 mi) down were never found, nor were basaltic layers at any depth.[14] There were instead more granites, deeper than predicted. The prediction of a transition at 7 kilometres was based on seismic waves indicating discontinuity, which could have been caused by a transition between rocks, or a metamorphic transition in the granite itself.[14] Water pooled 3–6 kilometres (1.9–3.7 mi) below the surface,[14][15] having percolated up through the granite until it reached a layer of impermeable rock.[16][17] This water did not naturally vaporize at any depth in the borehole.[15] The drilling mud that flowed out of the hole was described as "boiling" with an unexpected level of hydrogen gas.[18] Microscopic plankton fossils were found 6 kilometres (3.7 mi) below the surface.[1] """ [1] https://en.wikipedia.org/wiki/Kola_Superdeep_Borehole https://en.wikipedia.org/wiki/Kola_Superdeep_Borehole