No. 90: Nov-Dec 1993
If you could drop a pfennig down the KTB hole, it would take several minutes to hit bottom, for this research drill hole has now penetrated to 7.5 kilometers. It is the second deepest man-made hole, after the Soviet 12-km hole in the Kola Peninsula. Drilled solely for scientific purposes, the rocks and strata encountered by the KTB drill bits have forced the redrawing of German geological maps. The "real" subterranean world turned out to be quite different from that inferred from both surface indications and the seismic and electrical probing of the depths. Three specific surprises are worth mentioning:
"When I started 25 years ago, the idea was that the deeper you go into the crust, the drier it gets."
(Kerr, Richard A.; "Looking -- Deeply -- into the Earth's Crust in Europe," Science, 261:295, 1993.)
Comment. Deep-living bacteria were not mentioned in the above article, but Soviet scientists claim to have pumped them up from 12 km down! Outer space may not be our final frontier despite the introductory blurb to Star Trek!