Our Pick
Posted on @rawstates
The Marshall coal mines, still burning underground
1863
Marshall, Boulder County, Colorado
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Coal came out of the ground at Marshall from 1863 until 1939, and the fires left in the abandoned workings never went out. A 2018 state survey counted 38 coal seams still smouldering underground in Colorado, and the one under Marshall Mesa has been alight for more than a century. Investigators examined it as a possible cause of the December 2021 fire that burned through Superior and Louisville before settling on two other ignition points, and Boulder has since begun digging the smouldering coal out.
That was 1 of the hidden places.
Location: approximate area
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