which of the following factors was most important in controlling the distribution of copper mines in the u. s. versus iron mines in the great lakes region

The answer is the different ages and geologic histories of the rocks.

Explanation:

The Northern Great Lakes region has a lot of untapped potential in terms of exploratory drilling for copper, nickel and other heavy metals. Mining companies are actively seeking permits to conduct exploratory drilling on the Superior National Forest of northeast Minnesota for instance. The state of Minnesota owns the mineral rights and they have granted permits to allow more than 100,000 acres of state mineral rights. This concerns environmentalists because new mines would be in addition to the many that already exist in the area like open-pit iron-ore mines. There is already a legacy of pollution and harm to the invaluable water quality in the area. Lake Superior contains 10 percent of the world's freshwater.