Vol. II, pt. I-II, paged continuously. Accompanied by 2 folded maps: "Geological and topographical map of the anthracite fields ..." and "Geological map of the state ..." "On the origin and ...
In this part of Pennsylvania, subsidence is commonly associated with coal mining: When coal is removed from the earth, it leaves voids in its wake. Some collapse right away, sinking the surface above.
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