More often than not, the term “undermined” is used in a figurative way.
When considering the terrain around Linton, Indiana, on the other hand, geologists use the term literally.
Highly profitable for the owners of the 450-plus mines known to have existed in the Greene County area, coal mining has also been expensive, not only in terms of men’s lives, but the ecological toll it has taken.
At the turn of the century, if you happened to spot a seam of coal in an outcropping on your property, owning a mine was as simple as taking a pick and a shovel to the land to access the black gold below.
Most pits in the area were created using the technique of room-and-pillar mining, in which 20 to 50 percent of the coal is left standing in columns to support the mine roof.
When no more coal could be extracted without compromising the integrity of the underground structure, the mine would be abandoned.
Deep shaft mining continued in Greene County until the 1950s, giving way in the early 1970s to strip mining. Although the environmental hazards of the latter are well publicized, the nefarious legacy of underground mining lingers.
Undermined ground resembles a honeycomb of pillars and openings (or stopes). Subsidence, in which the mine roof collapses, is a risk for those above and below the surface even decades after a mine has been abandoned.
Acidic water and poor drainage are additional consequences, affecting native plant and animal species, not to mention agricultural productivity.
In 1941, Indiana was the second state to pass laws pertaining to the reclamation of once-mined land. Regulation did not become standard, however, until the passage of federal law in 1977.
These days, the Restoration Section of Indiana’s Department of Natural Resources administers the Federal Abandoned Mine Program, expenses of which are paid by mine operators.