Drilling Wyoming’s past

Posted 7/26/11

As part of a National Science Foundation-funded geological study, 27 scientists from 11 institutions have drilled near Basin and Polecat Bench to take core. In August, they turn to Gilmore Hill in the McCullough Peaks for further samples from the …

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Drilling Wyoming’s past


Scientists auger 50 million years into the past

Polecat Bench is a pristine plateau of swaying grass and surrounding mountains, but beneath the bench are clues of a global warming event millions of years ago.

Studying those clues from the past, including how fauna and flora acclimatized to warmer temperatures, will help predict the future, scientists say.

As part of a National Science Foundation-funded geological study, 27 scientists from 11 institutions have drilled near Basin and Polecat Bench to take core. In August, they turn to Gilmore Hill in the McCullough Peaks for further samples from the Paleocene-Eocene Thermal Maximum or, PETM.

A long time ago, the earth warmed significantly due to a large release of methane gas. Scientists hope to unearth the cause of the gas release and understand future global warming, said a news release from the University of New Hampshire in Durham.

Philip Gingerich, professor of geological sciences, biology and anthropology from the University of Michigan, Ann Arbor, spoke Tuesday, July 19, before a growling engine atop Polecat Bench that was spinning a drill to fetch core samples from beneath the ground.

About 55 million years ago, there was a huge release of seabed methane gas from within the South Atlantic. The frozen methane, deep within the ocean and under pressure, melted and rose from the sea into the atmosphere. “And methane is a powerful greenhouse gas,” Gingerich said.

The amount was equivalent to burning all the petroleum and other fossil fuels that exist today, said Will Clyde, associate professor of geology at the University of New Hampshire.

The release lasted around 10,000 years, and it took plants another 100,000 years to scrub the carbon dioxide from the atmosphere.

During that time the global temperature increased by 8 degrees Farenheit, Gingerich said.

That was during the interval of the Paleocene-Eocene (65 to 56.5 and 56.5 to 35.4 million years ago respectively) epochs, he said.

The Paleocene epoch is the time after dinosaurs and Eocene is the time of horses and other mammals.

Horses were small during the Eocene, about the size of a fox, as was an equine unearthed from that period in Sand Coulee, Gingerich said.

Horses and other mammals during the Paleocene-Eocene Thermal Maximum were dwarfed. A horse skeleton from that era was found near Polecat Bench. “And it was the size of a Siamese cat,” Gingerich said.

Although plants during the Paleocene-Eocene Thermal Maximum were growing from absorption of carbon dioxide, the nutrition yield was meager, so animals became smaller, Gingerich said.

Scientists with the project are hoping to recover a record of change in the composition of organic compounds.

Round and round goes the huge bit spinning into the soil at Polecat Bench. Every few minutes, the guys from Ruen Drilling, Inc., of Clark Fork, Idaho, remove a core sample.

The samples, in plastic sleeves that resemble a piece of clear PVC about 5 feet by 3 inches, are eased from the steel casing.

Equine or other mammal bones are not likely to be exhumed from the samples, but they do hope to find pollen and other organic (once living) matter that will indicate the climate during the Paleocene-Eocene boundary, Gingerich said.

“This is all what we call sedimentary rock,” said Cody Halliday, a Ruen employee hoisting a plastic-encased sample.

The scientists are examining the samples, but extensive analysis will come about in Bremen, Germany.

“We will meet there next winter to carry out an intensive sampling protocol, and then the real studies will begin,” Gingerich said in an email earlier this month. “Results will start to be available approximately a year from now.”

One sample from 44 feet beneath the surface weighs about 22 pounds.

“It is mud stone,” said Scott Wing, research geologist for the Smithsonian Institute in Washington, D.C.

Thanks to water used for drilling, the samples resemble chunks of damp cement that crumbles in the hand.

The gray tubes are stashed in a trailer for transport to Germany. Taking 120 samples from the Polecat site will give scientists specimens that have not been weathered or oxidized, Gingerich said.

In Bremen, they won’t analyze every square inch of core samples, said Johan Weijers, organic-geologist chemist from Utrecht University in the Netherlands.

Manipulating a cold chisel like a knife, Weijers slices a sample with the consistency of lumpy gray Play-doh the size of a petri dish. “It is really soft,” Weijers said.

Meanwhile, oblivious to the scientific survey, a few cattle graze in the distance and a hawk swoops over the contours as raptors have done for many millenniums here.

Standing on the threshold of history — or prehistory — Gingerich faces Wyo. 294, or Badger Basin. Here the earliest tapirs, horses, cows, sheep, goats and the first primates lived, he said.

Like the red bands striping mounds footing the bench, similar red beds run all the way to Greybull, but below Gingerich’s feet are where most of the primordial fossils are found, he said.

In 1912, the first fossils were collected below Polecat Bench, and its been going on ever since.

“It’s famous all over the world, this end of Polecat Bench ... with scientists anyway,” Gingerich said.

Gingerich said knowledge of the past can help predict the future.

If the atmosphere is warmed by increasing carbon dioxide, that heat will penetrate the ocean. In turn, warmer seas will thaw sea floor methane, triggering more gas rising to the surface and atmosphere, he said.

“It’s buried there today,” Gingerich said.