And all of-

Seams are layers in the earth where the coal is.

It's where the mines are set up to extract the coal.

And until I saw this, I didn't really understand how modern coal mining worked.

I thought it was still like Kathy's grandfathers described, 30 inches tall and picked out with hand tools.

This mine, the Upper Big Branch mine, is a colossal compound in the hills.

Upper Big Branch used to be one of West Virginia's largest coal producers.

Mmm.