Rock Hounds Drawn to Indiana Road Cuts

B E D F O R D, Ind., March 15, 2004 -- The hills of southern Indiana presented a uniquechallenge for roadbuilders during the construction of Indiana 37 inthe late 1960s and early '70s. When they couldn't go over the hillsor around them, they went through them.

The resulting "road cuts," shear walls of exposed rock, are asdistinctive a feature in the southern half of the state ascornfields are in the northern half.

It wasn't long after their appearance that the road cutsstarting drawing geologists and amateur rock hounds, who were eagerto get a closer look at these exposed slices of earth.

Indiana University geology professor Robert Wintsch said thecuts along Indiana 37 offer a unique learning experience. Wintsch,who teaches freshmen geology courses, will take his classes onfield trips to local streams, quarries and to the rock walls alongthe highway.

"It's a beautiful place to explain how things that lived in theocean that covered Indiana 350 million years ago have beenpreserved," he said.

According to Wintsch, the makeup of cuts varies from place toplace along the highway. The northernmost ones, just north andsouth of the Beanblossom Creek valley north of Bloomington, arecomposed of a siltstone layer, called the Edwardsville Formation,topped with a layer of limestone, called the Harrodsburg Formation.

Finding Collectible Pieces

"The siltstone is cemented together poorly," Wintsch said."It will wash away like a sand dune. The limestone is moreresistant. That's why you get overhangs — the siltstone underneaththe limestone washes away."

For fossil and geode seekers and rock hounds, the place tosearch is the point of contact, where the siltstone meets thelimestone, Wintsch said.

"That's definitely where you find most of the fun, collectiblepieces," he said.

As you travel farther south you move into an area of thickerlimestone, called the Salem Formation. This is where the quarriesare found.

"It's homogenous so it doesn't break apart easily. This allowsit to be cut up into large pieces," Wintsch said. "But fossilsand geodes are very rare in this type of limestone." The long cut directly north of the Harrodsburg exit is alsoanother hot spot for fossil seekers and rock hounds. Not everyoneis looking for geodes or fossils, though.

Wintsch said the thinner limestone layers yield a moreslab-stone that could be used for outdoor architecture like apatio. And though he finds the gravel-sized piles of rocks at thebase of the cuts to be "less than interesting" he said it couldbe used as "agricultural limestone."

"Limestone has high levels of calcium carbonate, the same stufffound in Tums," Wintsch said. "If you have acidic soil thecrushed rock could help neutralize that."

A Solid Foundation

Ron and Angie Smith of Greenwood spent part of a Saturdayafternoon along Indiana 37, just north of the Indiana 58intersection, loading their truck with dinner plate-sized rocks.The couple had been to two quarries earlier in the day to try andpurchase rocks, but both of the quarries were closed.

They had first seen the loose rock along Indiana 37 whiletraveling to Spring Mill State Park to go hiking. They admittedthat this was not their first stop along the highway to collectstones.

"We're building a house on the north side of Bloomington," RonSmith said. "We're also building a pole barn [on the property] andwe're going to use the stones as part of the foundation."

They said they had never had the police or the highwaydepartment stop them, which, according to Duane Chastain of theState Highway Department is not a surprise.

Chastain, supervisor at Bedford Unit 3 with the Paoli Subdistrict, said stopping alongside the highway to pick up or chiprock is illegal and can be dangerous. "It's one of those things that's not really enforced,"Chastain said. "If we're out and we see someone stopped we'll askthem to move on. The problem is if they chip some rock out, morefalls. If you're not careful you'll get some good-sized boulderscoming down."

Chastain said his crew will clean up loose rock along thehighway at least once a year.

For those still wishing to go gather rocks and fossils, Wintschrecommends that, at the very least, a hard hat and steel-toed bootsshould be worn.

Distributed by The Associated Press