In the 1980s Rhone Poulanc operated a rare-earths mine at the former Republic Steel separator plant in Moriah, much of which remains on site, now overgrown in the woods. Here are the largest surface ruins of what was once a major iron mining region. Republic Steel took over the Witherbee-Sherman mines in 1939, expanding and modernizing the facilities during and after World War II. Production peaked in 1953, when more than two million tons of iron ore were excavated and processed. Operations ceased in 1971, leaving piles of slag, and sinkholes collapsing into mineshafts. Most of the direct evidence of a century of underground mining in the region around Moriah, such as the mills, shops, warehouses, and headframes, have been removed or overgrown. Beneath the surface, however, are miles of mineshafts, containing locomotives and other equipment, suspended in a flood of groundwater.