Monday, November 6, 2023

Nature: Ohio's Metzger Preserve harbors strange yet impressive rock formations

Metzger Preserve harbors one of the state's greatest concentrations of the bizarre, round rock formations known as concretions/Jim McCormac

Nature: Ohio's Metzger Preserve harbors strange yet impressive rock formations

Columbus Dispatch
November 5, 2023

Jim McCormac

The Pekowi were a band of the Shawnee tribe, one of five divisions of the once-great confederacy. The county just south of Franklin County derives its name from the Pekowi: Pickaway. Until nearly 1800, the Shawnee and other Native Americans reigned over the wildlands of the Ohio country. An especially famous Shawnee was Tecumseh, who was born circa 1768 near Chillicothe.

At the time of Tecumseh’s birth, what would become Pickaway County was densely forested, the woodlands broken by a roughly 5-by-7-mile tract of prairie that bordered the Scioto River between present day Circleville and Chillicothe. It is known as the Pickaway Plains, but the prairie’s destruction is almost absolute. Less than a fraction of a percent remains.

In the early 1770’s, a Christian missionary named David Jones ambled into the Pickaway Plains region, seeking converts. Such missionaries were often harbingers of doom for the indigenous peoples, and soon an avalanche of settlers followed. The bounty of timber was irresistible to the immigrants, and the first lumber mill, near present-day Williamsport, began service in 1812. More soon followed. Before long, the forest primeval had been largely cleared.

An inventor named John Deere, who had fled his home state of Vermont to Illinois to dodge bankruptcy charges, wasted no time in his adopted state. In 1837, one year after his arrival, Deere launched his self-scouring steel plow which would forever alter the former forests and prairies of the Midwest and its nearly incalculable biodiversity.

By the dawn of the 20th century, most of Pickaway County had been converted from forests, prairies, pothole wetlands and fens harboring a thousand native plants to monocultures of corn, soybeans and wheat. Only scattered shards of former habitats remain.

In 2002, the Pickaway County Park District was created. For its first 15 years, the district operated on a shoestring budget, but in 2017 a levy to provide permanent funding for the park district was put before Pickaway County voters. They passed it with 55% of the vote. The district has not let the grass grow under its feet since, and is hard at work protecting Pickaway County natural gems.

Pickaway County Parks purchased the 52-acre Metzger Preserve along Deer Creek in 2019. Deer Creek is one of central Ohio’s finest streams, and this acquisition helps protect its water quality and rare fishes. But the preserve also offers the public a window into a geological history that is far older than the region’s human history.

On Oct. 28, I visited Metzger with Shauna Weyrauch, an Ohio State University professor and bobcat researcher. We weren’t looking for wildcats — they would have been common in Tecumseh’s time — but for a more easily found subject: rocks.

Metzger Preserve harbors one of the state’s greatest concentrations of concretions: bizarre round rock formations that look like oversized bowling balls. Concretions were formed by a buildup of minerals congealing around a nucleus such as a fossil, bone fragment or crystal. Metzger’s concretions are composed of siderite, an iron carbonate. The stony oddities date to the Devonian, a period of the Paleozoic Era that began 419 million years ago and lasted for 60 million years. So strange is their appearance that concretions were once thought by some to be dinosaur eggs, or flotsam left by extraterrestrials.

The concretions at Metzger Preserve are embedded in a deposit of Ohio Shale. Deer Creek has cut into this shale bank over the ages, eroding away the softer shale and liberating numerous concretions. The result is a fantastic, almost surreal streambed littered with what looks like castoff cannonballs. From afar, the rounded tops of the concretions resemble scores of turtle shells jutting from the water. Big specimens can be 8 feet in diameter.

If you visit Metzger, be sure to go when Deer Creek’s water levels are low and the concretions are easily visible. Another recommended stop nearby is Calamus Swamp, one of very few glacial kettle lakes remaining in the region. It is owned by Columbus Audubon and features a boardwalk that traverses the 19-acre wetland.

For more information on Metzger Preserve and Calamus Swamp, visit: and

Naturalist Jim McCormac writes a column for The Dispatch on the first, third and fifth Sundays of the month. He also writes about nature


Unknown said...

I seem to recall that they found concretions similar to those in your recent article when they were constructing the extension of 315. I beleive that they found them when excavating along the Olentangy River. Does this ring a bell with you? J. Thomas Jones

Jim McCormac said...

Hi Tom, yeah, good memory and I do vaguely recall that