A Tropical 'Rain Gauge'

Revealing Secrets in the Depths of South America's Largest Lake p.3

"Old-time marine geologists did a lot of coring," Baker said, "but there's not too much expertise for that left in the oceanographic community." On the continents, coring on lakes as deep as Titicaca,"hasn't been done before," Baker added. Depths average 443 feet in Titicaca's largest and deepest arm, Lago Grande.

The researchers first began their coring and seismic studies back in 1996, after delays caused by Shining Path guerilla activities in Peru, which shares Lake Titicaca with Bolivia. They first used a 29-foot boat called the Yakuza as part of a Peruvian-Bolivian lake research agreement with funding from the National Science Foundation(NSF). With little deck space, Yakuza was too small to gather cores longer than six to 10 feet. Baker and Seltzer had to lower and raise coring pipes with a hand winch, while Fritz knelt in a rubber boat lifting up retrieved cores from water "It was "killer work" at that oxygen deficient altitude," according to Baker.

Then another colleague of Baker's helped find a bigger boat. Geologist and coring expert James Broda of the Woods Hole Oceanographic Institution in Woods Hole, Mass., located the 38-foot Neecho in mothballs at a nearby U.S. Geological Survey station. Broda had that vessel and its 50-foot trailer towed to the institution, where cleanup and refurbishing began. Neecho was built for seismic studies in deep lakes. Broda added lighter weight versions of the kind of coring gear used in oceans. Those included two power winches to raise and lower heavy gear, and an "A-frame" crane that pivots out over the water to better assemble and drop strings of pipe. Meanwhile, Neecho's large air compressor could be used to provide shock waves for seismic studies.

The boat was refurbished and outfitted with more funding from the NSF, and Baker had its ownership transferred from the geological survey to Duke. Fritz told him he was "absolutely nuts" when he first proposed moving the Neecho to the roof of landlocked Bolivia. It seemed too much like the plot of the film Fitzcarraldo, in which actor Klaus Kinski's character tried to start an opera in a jungle after having a large river boat hauled over a mountain. Nevertheless, vessel and trailer left Woods Hole by truck in 1997. They sailed aboard a container ship from Newark, N.J., to Arica, Chile. Another truck then tugged them up through a 16,000-foot Andean pass. Neecho ended up on the dock of the Inca Utama Hotel, a spa at the town of Huatajata on Lago Hui'aiñarca, Titicaca's smaller and shallower arm.

Their roomier boat let the team handle bigger cores. It also provided more reassurance in heavy weather. This lake can be dangerous, with thunderstorms, waterspouts and even monster waves. "You don't want to have a problem on this lake," Baker said. "There's nobody who can come out and help you."

Analyzing their accumulating information, the team began publishing some important papers in scientific journals. A 1998 report in Geology, principally authored by Seltzer, used seismic reflection profile data collected aboard the Yakuza to document a 278-foot drop in lake levels between about 4,000 and 6,000 years ago.

The team's report last January in Science used core sediment analysis to deduce a precipitation record going back 25,000 years in both arms of the lake. Using the Neecho to collect cores as long as 46 feet in water as deep as 754 feet, that article asserted that the lake was especially fresh and deep during Earth's last ice age and other especially cold intervals. "We have a unique record of climate change in tropical South America that shows when global climate conditions cooled and the glaciers advanced, wetter climates prevailed in the Andes," Baker said.

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