An expert told News 12 that more damage is possible following the formation of sinkhole on Interstate 80 in Wharton.

As of Saturday night, there is no timetable on when the portion of the roadway that was destroyed by a sinkhole will reopen. The Department of Transportation said Friday that it broke when an abandoned mineshaft collapsed.

Sterling Hill Mining Museum president Bill Kroth told News 12 that these mines are abundant in the area, and must be treated with caution.

“It's Swiss cheese underground,” Kroth said. “I used to do home inspections. I had a lot in that area, and it's indeterminate whether it's safe or not.”

Kroth said that in Revolutionary times, North Jersey’s mines were a national leader in iron ore. But when they are abandoned and eventually collapse, they can cause a 21st-century headache.

“They did not have the safety rules as far as capping and backfilling mines the way we have today,” Kroth said. “So, things were kind of left unsettled.”

Although the exact cause of the collapse is unclear, Kroth believes factors could include April’s earthquake or the recent autumn drought.

Maps from the New Jersey Department of Environmental Protection show a small cluster of these abandoned mines near I-80.

“You can't just assume everything else is OK,” Kroth said. “If that would have happened in one of the travel lanes, there would have been fatalities.”

Crews stabilized the workzone Friday.