Las Animas County sits over Raton Basin coal, which shapes the ground underneath

The mountains and mesas of Las Animas County sit over the Raton Basin, a thick stack of rock that holds some of Colorado’s best-known coal. That coal is why mining towns grew here, and it is also why the ground under parts of the county is not simple.

Where coal was dug out underground, the old workings did not vanish. Over the years, the roof of an old mine can settle, and the surface above it can sink or crack. Geologists call this subsidence. The same coal also holds methane gas, which is why the basin later saw coal-bed methane wells. None of this means a given piece of land is unsafe, but it does mean the question is worth asking, especially near former mining areas.

For a buyer, this is a “look below the surface” reminder. Before counting on a building site, it is fair to ask whether old mine workings, gas, or known subsidence have been mapped nearby. A general listing will not tell you that. State geologists keep records and maps that can.

To check whether a specific area has known abandoned-mine or subsidence concerns, start with the Colorado Geological Survey, and ask the county about any local building requirements.