They were probably mountaintop removal quarries in the past, but I am pretty sure that they are now landfill/dumping ground for rock/dirt/excavated material.
(On Bing) It looks like they are piling up material everywhere or did at some point, but not like they are still digging for material. On the south/southwest on these areas are two very large dams. The material is likely from underground mines in the area.
Compare e.g. with an active quarry https://www.openstreetmap.org/edit?#map=13/37.77786/-81.61654
I think there is a noticeable difference

Maybe there are also better tags such as was:quarry+natural=scree/scrub or something, i don't think it is a quarry. But no strong feelings either way.