2 ms·
To save you a search https://en.m.wikipedia.org/wiki/Kola_Superdeep_Borehole https://en.m.wikipedia.org/wiki/Kola_Superdeep_Borehole
by kubafu 5y ago
To save you a search https://en.m.wikipedia.org/wiki/Kola_Superdeep_Borehole https://en.m.wikipedia.org/wiki/Kola_Superdeep_Borehole