ELY, MINN. | Oct. 28, 2026, 12:52 p.m. ET | 11 min read

Around 1.1 billion years ago, North America tried to rip itself in half. The attempt was unsuccessful, of course – otherwise, there would be an ocean where Lake Superior is today. But the Midcontinent Rift, as it is known, across northern Minnesota caused magma to bubble up from the Earth’s mantle, bringing with it vast amounts of copper, nickel, and other critical minerals for which countries all over the world are now furiously digging, to power everything from the latest iPhone to electric vehicles.

Fast-forward a billion or so years from the time of Minnesotan volcanoes, and something else happened on this stretch of land: The ice sheets covering the area began to recede, leaving divots that soon filled with fresh water.…