Sinkholes, Bane of Today's Drivers, Offer Peek Into a Lost Mining Past

New York Times

25-05-2025

Just after Christmas last year, the eastbound shoulder along a New Jersey stretch of Interstate 80 parted like an asphalt curtain. It left a hole 40 feet wide, 40 feet long and deep enough to imagine the worst.
Crews from the state's Department of Transportation worked around the clock to repair the ominous breach with wire mesh, stones, concrete and several layers of asphalt. Within four days, I-80 traffic resumed as if nothing had happened. As if the New Jersey earth had not suddenly opened up in the town of Wharton.
But then it happened again, in early February, just two dozen yards from the first breach. A just-noticed depression in the roadway suddenly collapsed, leaving a sinkhole large enough to swallow an S.U.V.
And then again, in mid-March. A 25-foot-deep sinkhole yawned open along the median in the eastbound work zone, followed by detection of a significant void under the westbound lane. A slice of interstate was closed in both directions, while state transportation officials grappled with an infrastructural problem whose cause they knew:
The past.
As I-80 cuts through the New Jersey highlands, enduring the east-west movement of 110,000 vehicles every day, it passes over at least two of the many abandoned iron mines that honeycomb the area. These are the remnants of a thriving ore-and-mineral industry that began before the American Revolution and lasted into the 1970s.
The names on the exit signs — Hibernia, Rockaway, Mount Hope, Dover, Wharton, Mine Hill — are of communities once defined by their dependence on iron. The people who settled here — the English and Welsh, the Irish and Eastern European, and, later, the Puerto Rican — worked away at the bedrock below, following its veins ever deeper into the underworld until the market dried up or the costs became prohibitive.
Last year, in an extensive report about hazard mitigation, the New Jersey Office of Emergency Management addressed the state's 'susceptibility to subsidence,' or the sinking of land, 'due in part to its large number of abandoned mines.'
At issue, the report said, was that some of the abandoned mines were not mapped accurately. Also, the surface openings of many mines weren't filled in properly and had since had roads built on top of them.
Abandoned mines, mostly forgotten — until another sinkhole develops in an inconvenient spot; the center of an interstate, for example. It is as though, every now and then, New Jersey's past needs to remind New Jersey's present exactly what the state is built on. Its rock, yes, but also its people.
'It was a rough-and-tumble life,' said Jan Williams, the cultural and historic resources specialist for the Morris County Office of Planning and Preservation. 'But it was a starting-off place for a lot of immigrants. In many cases their children were out of the mines, running stores, running businesses.'
In other words, the American way.
There is not an abundance of information about the everyday lives of the miners. Above ground, they created communities, built churches, formed baseball teams and reveled in the daylight; below ground, they dug, drilled and dynamited for the man.
Shortly after the end of the Civil War in 1865, a New York Times correspondent with a gift for casual condescension journeyed through 'The New-Jersey Mineral Region.' Stopping in Hibernia, he described the company housing as far from comfortable in winter, but serviceable. As for the miners themselves — English, Welsh and, mostly, Irish — he wrote that 'if they look less intelligent, their physique is greatly superior.'
'On the whole, though some of them occasionally 'go on the spree,' or 'kick up a shindy,' there is less trouble among them than might be expected,' the correspondent wrote. 'A great deal, however, depends on the tact, kindness and firmness of the managers.'
Dispatches like this highlighted the need for better information. Three years ago, Ms. Williams issued an appeal to residents in and around Morris County for any information about ancestors who had been miners. She wrote: 'History has recorded the names of the mining barons; however, the miners have been largely forgotten.'
Her appeal has resulted in a file called, simply, 'Morris County's Miners.' It includes the scant backgrounds of dozens of miners, drawn from census records, death notices, family photographs and news accounts, most of them concerning fatalities below ground.
'Nobody cared,' said Joe Macasek, a local historian. 'These were working guys doing dangerous jobs in dangerous places. And they were simply let go if the market changed.'
Two men killed when staging gave way in the Dodge mine. A man killed by an explosion of dynamite in the Hurd mine. Six men killed in the Richard mine. A 14-year-old boy killed in the Mount Hope mine. A man crushed by a falling rock in the Andover mine. A man killed by an explosion of black powder in the King mine. A dozen men drowned in the Hibernia mine.
There was, though, the occasional miracle, including one recorded by The Morris County Chronicle in 1887: 'A miner named Jack Connel, while unloading buckets at the mouth of the Orchard mine shaft, Port Oram, a few days ago, lost his footing and fell a distance of 100 feet, but climbed out unhurt, save a few slight bruises.'
The sinkholes plaguing I-80 are believed to be related to two small-scale operations, the Huff mine, which was worked from 1855 to about 1910, and the Mount Pleasant mine, which opened in 1786 and closed around 1896. Their production and dimensions were recorded for posterity — the Mount Pleasant mine was about 1,400 feet deep, for example — but not so much the daily lives of their laborers.
In 1879, two miners, Thomas Champion and William Lowery, were tamping a hole with common blasting powder when the charge prematurely exploded in their faces. The injuries 'were beyond the endurance of even such a strong man,' The Iron Era reported. Mr. Champion, married and father of six, died, followed soon after by Mr. Lowery, married and father of four.
Remnants of what was are scattered like silvery flecks throughout the highlands. The image on the Rockaway township seal is an anvil. The tombstones in the old cemeteries carry the Irish, English and Eastern European surnames. And in Ogdensburg, about 15 miles north of the compromised section of I-80, you can walk into the damp coolness of an old zinc mine at the Sterling Hill Mining Museum, and then have a pasty — a hand-held meat pie associated with Cornish miners — at the snack bar.
The museum's enthusiastic president, William Kroth, is a geotechnical engineer whose general thought about the sinkholes is: What do you think would happen if you built a superhighway over abandoned mines?
Mr. Kroth has theories about why the sinkholes have suddenly developed along this part of I-80, some 60 years after its construction. It could be related to an earthquake in 2024, the most powerful in New Jersey in more than two centuries. Or that year's drought, which could have lowered the water table, increasing the stress on the rock and soil. Or the supporting timbers of a mine could have rotted away, causing a collapse into an abandoned tunnel. Or all of the above.
Whatever the reason, Mr. Kroth said, 'that whole area is Swiss cheese.'
To address the problems caused by the past, the Department of Transportation is making permanent repairs and installing a monitoring system, including remote sensing technology, to track conditions underground and on the surface. The department said it was evaluating other mines located near roadways and working with other government agencies 'to develop long-term monitoring.'
For now, two eastbound lanes on I-80 have recently opened, and two westbound lanes are expected to open by the end of May. But sinkhole repairs on the highway will continue well into late June.
The speed limit will be reduced to 40 miles per hour, forcing motorists to at least slow down as they pass through a work zone of concrete, asphalt and ghosts.