More than half of the electricity generated in the United States is produced by coal-fired power plants. Generally, only a small percentage of the coal used in those plants comes from the controversial practice of mountaintop removal mining, or MTR, which involves the use of heavy explosives to blast away up to 1,000 vertical feet of a mountain after its surface has been cleared of timber. What 1970s crises first sparked an increase in the demand for coal and triggered the widespread use of MTR? Discuss