The entrance to an advertisement at the Sterling Hill Mining Museum is located below a chute used to bring processed ore to silos for distribution on October 17, 2017.David M. Zimmer/NorthJersey.comA possible mine not found on state maps is located under large stones near a small air shaft next to Weldon Road in Jefferson Township. The suspected mine could be among hundreds of test pits and other small mines that have never been documented.David M. Zimmer/NorthJersey.comA group of drills line the wall of an advertisement at the Sterling Hill Mine on October 17, 2017.David M. Zimmer/NorthJersey.comDistinctive layers of rock are visible in the interior of the Sterling Hill Mine in Ogdensburg on October 17, 2017.David M. Zimmer/NorthJersey.comOld metals and mining equipment fill nearly every corner at the Sterling Hill Mining Museum on October 17, 2017.David M. Zimmer/NorthJersey.comRelics of past mining operations abound at the Sterling Hill Mining Museum on October 17, 2017.David M. Zimmer/NorthJersey.comThe Schofield Mine in Jefferson Township is a huge ditch filled with trash on December 8, 2017. Many abandoned mines have been used to dispose of trash in the decades since they closed.David M. Zimmer/NorthJersey.comA tour guide at the Sterling Hill Mining Museum leads a group through the former zinc mine on October 17, 2017.David M. Zimmer/NorthJersey.comA grizzly, a grate that catches rocks larger than entering the mine cars below, lies above a swimming pool at the Sterling Mine on October 17, 2017.David M. Zimmer/NorthJersey.comA variety of signs line the walls of the lantern room at the Sterling Mine, as seen on October 17, 2017.David M. Zimmer/NorthJersey.comThe Sterling Hill Mining Museum in Ogdenburg, as seen on October 17, 2017, operates in and around one of the world's most famous zinc mines.David M. Zimmer/NorthJersey.comA massive mine at Sterling Hill carried everything from ore to people to and from depths of about 1,900 feet.David M. Zimmer/NorthJersey.comA flooded tunnel in one of the oldest sections of the Sterling Hill mine looks eerily quiet on October 17, 2017.David M. Zimmer/NorthJersey.comThe flooded Ford Mine in Jefferson Township, as seen on December 8, 2017, is down the road from the Dodge Mine. The huge moat sits atop the berm and is mostly hidden from passersby.David M. Zimmer/NorthJersey.comThe Odgen Mine sand rail track in Jefferson Township was used to transport ore from dozens of iron mines in the area. Viewed on December 8, 2017, the flat railway bed is now used as a hiking trail.David M. Zimmer/NorthJersey.comA chain link fence surrounds an abandoned mine shaft at the Dodge Mine in Jefferson Township as seen on December 8, 2017.David M. Zimmer/NorthJersey.comWater is still present in the canals at the Edison Mine in Ogdensburg, on October 17, 2017. Thomas Edison ran the mine that processed low-grade iron ore from nearby veins.David M. Zimmer/NorthJersey.comThe Heard Mine in Jefferson Township was the deepest in New Jersey. The mine, seen on October 17, 2017, is now covered in waste rock that provides the only hint of its past.David M. Zimmer/NorthJersey.comThe Odgen Mine Railroad in Jefferson Township, seen on December 8, 2017, was designed to remain relatively flat as it ran through the lumpy upland area.David M. Zimmer/NorthJersey.comA swimming pool fills an abandoned mine at the Edison Mine Complex in Ogdenburg on October 17, 2017.David M. Zimmer/NorthJersey.comThis map of the Ringwood iron mining district dates from 1864. Ringwood, a Passaic County county bordering New York State, had six large mines in operation at the time.New Jersey Department of Environmental ProtectionA wall of iron-colored rock rests above a shallow pond in the Edison Mine area in Ogdensburg on October 17, 2017.David M. Zimmer/NorthJersey.comA narrow shaft in the Edison Mine area in Ogdensburg on October 17, 2017 shows the small size of some of the iron ore veins in the area.David M. Zimmer/NorthJersey.comThe stone walls from the Dodge Mine operation are located in Jefferson Township, New Jersey, just off Weldon Road. The road passes through a county-owned reserve as seen on December 8, 2017.David M. Zimmer/NorthJersey.comOne of several remaining open pits at the Edison Mine site in Ogdenburg is surrounded by fencing and hiking trails on October 17, 2017.David M. Zimmer/NorthJersey.comA former mine in the Edison Mine Complex was flooded on October 17, 2017.David M. Zimmer/NorthJersey.comThe Edison Mine operation in Ogdensburg has a channel network. The site, seen on October 17, 2017, was owned by Thomas Edison.David M. Zimmer/NorthJersey.comAn entrance to the Ringwood Mines Superfund site located at the end of Peters Mine Road near Sheehan Drive in Ringwood as seen on February 22, 2016.Mitsuo Yasukawa/NorthJersey.comA large sinkhole opened in November near Van Dunk Lane in Upper Ringwood. It's a chronic problem near the town's Superfund site where 18th-century mines are collapsing.File imageRingwood is fencing off land between Horseshoe Bend and Margaret King roads, as seen on Jan. 4. Officials say the property is vulnerable to collapse.Joe Sarno/NorthJersey.comThe Dodge Mine in Jefferson Township, New Jersey, has a new temporary fence around one of its many iron mine shafts.David M. Zimmer/NorthJersey.comThe Dodge Mine in Jefferson Township, New Jersey, has a new temporary fence around one of several iron mine shafts believed to drop more than 100 feet below a quiet county park.David M. Zimmer/NorthJersey.comThe Dodge Mine in Jefferson Township, New Jersey, has a new temporary fence around one of several iron mine shafts believed to drop more than 100 feet below a quiet county park.David M. Zimmer/NorthJersey.com https://www.northjersey.com/gcdn/-mm-/72d7a379e79c1e2d3c2cb6f4c6c56235a664d809/c=0-373-4032-2651/local/-/media/2018/01/04/Bergen/NorthJersey/636506578904443673-SuspectedMineWeldonRoad-2-.JPG?width=3200&height=1808&fit=crop&format=pjpg&auto=webp