Last night I ventured out for the first public event I’ve attended since my surgery — Blue Mounds Area Project’s  presentation in Mount Horeb, A Geologic Romp through the Driftless Area by Dr. Richard Slaughter, UW Geology Museum Director.

I’m always ready to learn more about the geology of the Driftless Area in southwestern Wisconsin.  The gathering was held at the Wisconsin Geological and Natural History Research Collection and Education Center.

All these very strong shelves are holding Wisconsin's library of rock.

Before the very engaging talk by Dr. Slaughter, we heard from Patrick McLaughlin, geologist for the Wisconsin Geological and Natural History Survey, who told us about the facility where we were meeting.

I was blown away!

I had no idea such a collection existed or that I had been driving a block away from it for years.   

Here’s what is sitting silently in a very large, very anonymous building:

Rock cores (most about an inch in diameter)

• Cores from more than 2,000 drill holes throughout the state are cataloged and available for study.
• These cores comprise more than 600,000 linear feet of subsurface rock samples from mineral, engineering, and geologic investigations.

Close up of boxes of carefully labeled drilling cores

Water-well cuttings

• Cuttings from more than 11,000 individual water-wells throughout the state are available.
• These cuttings include 570,000 individual samples, each covering a 5-foot interval, collectively representing approximately 2.7 million linear feet of drilling

Individual rock samples

• More than 51,000 hand-size rock samples are labeled and stored.

McLaughlin said that when the Wisconsin Geological Survey acquired this warehouse and office building about five years ago, it took 20 semi truck loads to transfer this subsurface collection.  He calls it a kind of library and estimates the present-day replacement cost of the collection is conservatively estimated to be $120-140 million.

The reddish cores on the right were once mined for paint pigment.

These samples represent hundreds of investigations of the geology of Wisconsin, and many of these samples are irreplaceable.  For example, some come from a project in the 1980’s when Milwaukee was designing a deep tunnel project under the city to handle rain water overflow.  It would be impossible to recollect these cores now.

Many of the cores come from mining operations in northern Wisconsin.  The deepest cores come from oil exploration.  There is one core that pierced almost 5,000 feet into the earth.

Collecting cores today costs about $60 a foot, so a 1,000 foot costs $60,000.  Sometimes these can be funded by the  U.S. Geological Survey grant, but as most of them have been donated by industry, it’s an amazing bargain.

Wisconsin has one of the largest collections in the Midwest, but the state with the biggest collection is Texas due to the extensive oil and gas drilling activity there.

This collection represents a record of what is under our feet, and it is used for many studies, primarily ground water flow.

As it explains in the website, protecting these materials is vital because

• geologists frequently re-analyze existing samples whenever new environmental issues come to the forefront
• advances in technology and equipment allow for different types of analyses
• geologic theory evolves

The Wisconsin Geological and Natural History Research Collection and Education Center seems almost as underground as the source of its collection.  You could walk by it every day and not know it is there.  But it is, and we are lucky it is.  Who knows what vital knowledge is waiting quietly in those shelves and shelves of carefully stored cylinders of rock?