Boxes of rocks serve as history books

By SPENCER HUNT

Researchers are checking some samples to see if carbon dioxide can be safely stored deep underground.

LEWIS CENTER, Ohio — To Gregory Schumacher, the Ohio Geological Sample Repository is a vast library; its boxes of rocks are history books waiting to be read.

“Every one has a story to tell,” said Schumacher, a state geologist who oversees the collection in Delaware County.

These stories, he said, help explain the Earth’s history from the ground down.

“It’s an invaluable archive of information,” said Stig Bergstrom, a retired Ohio State University geologist who uses microfossils found in limestone cores to help map the location of ancient continents and land masses.

By matching tiny fossils of worms called conodonts found in Ohio cores to those found in Europe and Asia during similar periods, geologists can map land masses that disappeared hundreds of millions of years ago.

Records show that 149 geologists, mostly professors and their students, visited the repository last year. Visitors included consulting geologists from 10 oil and gas companies.

There are 55 miles of core-sample sections and 5,000 sets of well cuttings in the boxes that fill the huge shelves.

Each core sample is in its own box and is labeled with the location and county from which it was taken, the date it was removed and its depth.

Cuttings are kept in small envelopes similarly labeled and filed in long rows of narrow cardboard boxes.

Schumacher said that the oldest samples date to the 1940s.

The assembled cores come from 845 sites in 85 of the state’s 88 counties. Licking, Miami and Paulding counties are not represented.

A rock core can reveal everything from the extent of Ohio’s coal beds and crude-oil fields to the evolution of the planet and the life cycles of nearby stars.

The repository also keeps well cuttings — crushed bits of rock and dust — collected from more than 5,000 drill sites across the state.

Cores are drilled with special bits coated with industrial diamonds and slowly drawn from deep underground. Researchers would have to spend thousands of dollars to drill samples on their own, said Michael Angle, a geologist and supervisor with the Ohio Geological Survey.

“It can take a whole afternoon or a whole day to pull one sample out of the ground,” Angle said. “Time is money.”

As with any library, the information on file at the repository is free.

Schumacher said consultants often look for information that can help confirm their work detecting oil, natural gas or other minerals at potential well and mine sites.

Geologists often look for porosity, or how well fluids pass through rocks. The higher the porosity, the better a site will be for drinking water or oil wells.

Mort Schmidt, a geologist with Plain City-based Cox-Colvin and Associates Inc. Environmental Services, donated a core in 2006 that showed compacted mud in an area of Richland County.

State geological maps estimated that the area was part of a valley that an ice-age glacier should have left filled with sand and gravel.

Schmidt said his core will help companies interested in the area.

“You don’t want to buy some land for a sand-and-gravel operation if the information is wrong,” Schmidt said. “If you started digging and found nothing but mud, that would cost you a lot of money.”

The repository also includes samples that researchers are looking at to see whether carbon dioxide, a key global warming gas, can be safely stored deep underground.

Scientists long have speculated that carbon-dioxide emissions from coal-fired power plants could be pumped into porous rock formations and depleted oil and natural-gas wells, but the technology has to be proved and developed.

The International Energy Agency has said that if an effective method of carbon storage is found, sequestration could provide 15 percent to 20 percent of the greenhouse-gas reduction needed to stabilize Earth’s climate.

On a recent afternoon, a table in the geological sample repository was covered with cores of Rose Run sandstone drilled at about 6,500 feet beneath Morgan County.

“We’re looking for porous zones in the rock that will allow the carbon dioxide to be stored,” Schumacher said.

A layer of Knox dolomite, another type of rock found directly above the sandstone, also will be examined as a potential cap to keep the carbon dioxide trapped.

Schumacher is working with the Midwest Regional Carbon Sequestration Partnership, a research coalition led by Battelle that includes 35 state agencies, companies and universities in Indiana, Kentucky, Maryland, Michigan, New York, Pennsylvania and West Virginia.

In 2003, Schumacher and colleagues Richard Carlton, Mark Baranoski, Doyle Watts and Belgasem El-Saiti examined core samples taken at the Serpent Mound in Adams County.

There, sample rock had been mysteriously turned on its side in some event that occurred 255 million to 330 million years ago.

Using a microscope, Carlton examined quartz crystals taken from a core sample and found that many were melted, probably by a meteor that struck the area.

“He was pretty fired up,” Schumacher said. “It was probably the most excited he’s been in the 15 or so years I worked with him.”

The team’s report was published as an Ohio Geological Survey Report of Investigations in 2003.

Natalie Nahill, a doctoral student in geology at the University of Pennsylvania, is studying salt core samples that she believes might help astrophysicists unlock the secrets of how Milky Way stars age.

Nahill is examining cores taken from two Lake Erie underground salt mines to see how they were altered by muons from supernovas. Muons are charged particles that are similar to electrons and positrons, but are 200 times heavier. They are produced when cosmic rays hit our atmosphere.

A careful examination of the cores could help determine if a supernova occurred near Earth at some point.

Such a discovery, she said, would spur more research to see how the planet changed after such an event.

Schumacher said the repository is working with the U.S. Geological Survey to create a national catalog of core samples and cuttings that would be available at Ohio’s center and similar collections in 38 other states.

Betty Adrian, director of the Core Research Center in Denver, said she hopes to put the catalog online this year.

Adrian said that kind of information would help geologists determine whether a particular core is worth inspecting in person. For example, she said, researchers could request that a small plug from an Ohio sample be mailed to them.

Schumacher said an online listing would help geologists avoid having to drill for a sample that already exists.

“If you don’t know your history, you’re doomed to repeat it,” Schumacher said.