The Soviet Union has resumed drilling at the world's deepest hole on the Kola Peninsula west of Murmansk.
A Tass report said a rock sample has been recovered from a depth of 12,070 m (39,599 ft). Drilling in the Kola SG-3 well was suspended in December 1983 at 39,586 ft.
Moscow said drilling was stopped to install more powerful rig components "and to enable scientists to conduct a number of experiments."
Casing was run to nearly 9,000 m (29,527 ft). Casing of 245 mm diameter was previously set at 28,773 ft.
Soviet geologists are quoted as saying the superdeep hole is approaching "a mysterious seismic boundary of the earth's core, probably a diorite bed."
Drilling personnel predict SG-3 will approach the 13,000 m (42,650 ft) mark this year. In January 1988 the Soviet press said plans called for the hole to reach 14,000 m (45,931 ft) by the end of this year.
SG-3 was spudded in May 1970, and the original target was 15,000 m (49,212 ft). A Uralmash BU-15000 rig is on the hole.
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