What is mountain top mining?
I believe you are referring to strip mining. In parts of Kentucky, Ohio, Pennsylvania, Tennessee, Virginia and West Virginia, entire mountaintops have been shorn off in order to easily get to the coal lying beneath them. A drive up I-75 from Knoxville, TN to Lexington, KY reveals many such examples of strip mining wherein the hills and mountains once had rounded tops, but are now flat on top.