From deeper underground, he heard the grinding noises of heavy excavation machines, and shouted commands.

The men at the Giness now ride elevators down 1,500 feet, and they use high-speed excavation machines and computerized conveyer belts to get out the coal.

They set their excavation machines to work, connecting the caverns by a system of branching tunnels far below the stark and frozen surface.

Taking advantage of the confusion, Nathan takes the gem from Patrick and throws it to a nearby excavation machine.

Some said they hoped to find an answer to the tragedy by watching the excavation machines and the toiling rescue workers.

"I think they're excavation machines," Dall said.

In recent weeks, excavation machines have been pounding at the hard Manhattan bedrock to prepare a foundation for the new building.

She recalled that the excavation machines had been dusty and faded.

Some excavations were conducted by the city of Lappeenranta in December 2005, but using a very harsh methodology (excavation machine) and only a few bone fragments were found.

The rusting remains of the giant German-built excavation machine - nicknamed "Sarah" - are visible in satellite images near the south end of the canal.