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Susquehanna Life

Let a Visit to Michaux Forest Rock Your World

Jun 08, 2017 12:42AM ● By Melanie Heisinger

By Lara Lutz

Michaux State Forest, and the South Mountain ridges on which it rests, is a landscape first formed by shifting continents, later by the blaze of iron furnaces and then the stewardship of state foresters.

Geologist Sean Cornell, a professor at nearby Shippensburg University, uses Hammonds Rocks, about 15 miles south-southeast of Carlisle, PA, as an outdoor classroom of environmental change. “You can go back 540 million years and see that record here on the mountain,” Cornell says.

The experience

The walk to Hammonds Rocks is very short, if you travel to the northern end of the forest by car and park in the small pull-off area near the rocks. Ridge Road will have already carried you to the crest. The rocks seem to spill down the slope, and the higher you climb, the taller and more numerous they grow. They are rippled, grooved and streaked. Many angle sharply toward the sky.

Clamber onto the highest “tower”—once used as a fire watch station—and you’ll glimpse the valley sprawled below. The rocks beneath your feet are the remnants of a subtropical shoreline, formed more than 500 million years ago on a land mass that geologists know as the supercontinent Rodinia.

Historical backdrop

When the old continents began to shift and collide, oceans rose and drowned rocks like these, which had been deposited at the mouth of rivers. Then the land began to rise and fold. Fractures formed in the rocks as they rose, like gaps between cards in a flexed deck. What happened next set the stage for more recent history: The fractures were filled.

“When the Atlantic formed and rifted Africa away from North America, there were magma chambers,” Cornell says. “All that water traveled through those fractures, and it carried metals.” In some places, like South Mountain in Pennsylvania, the process created massive veins of iron.

Long after North America formed and rotated, moving what would become South Mountain into its current position in south-central Pennsylvania, the veins were mined for iron ore at such a frenetic pace that it transformed the mountain once again. Settlers created forges in the 1700s, and production was industrialized during the 1800s.

Utilizing nature’s gifts

Ironmaking required three things: iron ore, limestone and charcoal created from burned timber. South Mountain provided iron ore and a vast forest. Limestone was located at its base.

Ironmakers mixed the ore with limestone in a tall stone furnace fed by charcoal; the chemical reaction burned off impurities or “slag” in the ore. Chunks of blue-green slag can still be found on the grounds of Pine Grove Furnace State Park, where a large iron operation once stood.

Molten iron was drawn from the furnace and cooled into small bars for sale and transport. The line of iron bars in the cooling mold resembled piglets next to a sow and were known as “pig iron.”

Furnaces consumed hundreds of acres of trees every year. Young trees were harvested quickly because they burned more easily into charcoal. Nothing was replanted. When the iron works fell out of use in the late 1800s, a ravaged mountain was left in its wake. Local residents had almost no incentive for restoration.

Craig Houghton is a forestry professor at Penn State Mont Alto, located at the southern end of Michaux State Forest on the site of a former iron company. “Forest land was taxed at a very high rate, so people would cut it down," Houghton says. "It was repeatedly cut over and burned over, and forests were not growing back.”

Better forest management

When the state began to buy the land, there was little forest left, and almost none of it was healthy. Visitors today might have a hard time believing that, because Michaux State Forest alone includes more than 85,500 acres, almost entirely wooded. The Appalachian Trail is a forested corridor across the spine of the mountain.

The state forest was named for Andre Michaux, a French botanist who traveled the area in the late 1700s and was stunned by the devastation he saw when he returned a few decades later. Michaux willed Pennsylvania $12,000 at his death in 1855 to promote better forest management.

Roy Brubaker, district forester for Michaux, says the recovery there is still not complete. The regrown forest lacks its historic diversity of trees, he says, and some wildlife species, like grouse, are declining because of it. Still, much credit for the initial reforestation can be traced to a state forestry school that was established on the former grounds of the Mont Alto Iron Works.

The Pennsylvania State Forestry Academy, founded in 1903, was the first professional forestry program in Pennsylvania and only the second in the nation. Among the first graduating class, in 1906, was Ralph Brock, who is considered the nation’s first African-American forester.

Lay of the land

Growing recreational demands have challenged land management in Michaux, which can be reached in two hours or less from Harrisburg, Baltimore and the District of Columbia. As a state forest, instead of a state park that prioritizes recreation, the land is preserved for multiple reasons: ecosystem benefits like water quality and wildlife habitat; limited timber harvest; and public use. As hikers and cyclists spill from state parks to explore the forest, and large group events are on the rise, trails and signage in some areas are not well-developed or protective of sensitive areas.

Brubaker’s mission is to balance these uses. “We need people to understand the high bar we’ve got to meet if we want to reach our ecological goals,” Brubaker says.

At Hammonds Rocks, Brubaker’s staff worked with Cornell’s students to remove graffiti and install a sign. Tree clearing along the ridge will help restore the barrens habitat and reveal an expansive view. Connecting trails might be created. “It’s one of the nicest outcroppings in the forest," says Brubaker, “but it’s not really connected to anything else. . . . One of the best ways to get to know Michaux is to come with someone who knows it.”

Lara Lutz, of Bay Journal News Service, is a writer and editor who specializes in the environment, heritage and outdoors enjoyment of the Chesapeake region.

If You Go

Michaux offers primitive camping; Caledonia and Pine Grove Furnace state parks offer campgrounds with amenities. A portion of the Pine Grove iron furnace still stands, and the former ironmaster’s mansion is now a hostel. You’ll find small quiet lakes, several overlooks, and more than 60 miles of marked and unmarked trails, plus the Appalachian Trail. Secluded streams host native brook trout. Mountain biking, hiking, horseback riding and ATVs are popular activities.

More information is at or (717) 352-2211.

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