The Biggest Lava Flow in the U.S. is in the Keweenaw Peninsula, Michigan

So where did the majority of the Upper Peninsula’s copper come from? Volcanic lava. In fact, Michigan just may be home to the biggest lava flow in the country.

It was well over one billion years ago when volcanoes spewed forth 200 lava flows, one of which became known as the “Greenstone Flow” which is possibly the largest, not just in the country, but in the world. The hardened lava became covered in dirt, earth, and sediment; and through the years, faults and cracks in the Upper Peninsula’s earth exposed the rich deposits of copper. The glaciers which formed our Great Lakes also uncovered many copper ore deposits, and area natives ended up mining thousands of pounds of copper.

Thousands of years later, when Michigan became a state in 1837, state geologist Douglas Houghton was sent to the Upper Peninsula to search for places suitable for mining. By the 1840s, Michigan was home to the world’s largest known deposit of native copper.

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Houghton, Keweenaw, and Ontonagon Counties were the main sources for seemingly endless mines and mining towns. The hundreds of miles and thousands of acres during Michigan’s peak mining years contains what is believed to be some of the most beautiful land and scenery in the Keweenaw Peninsula. Some of the most breathtaking ones are thanks to lava flows.

The Greenstone Flow caused some of Michigan’s most awesome land masses. The flow goes from the Keweenaw Peninsula all the way across Lake Superior to Isle Royale. One of the best places a visitor can witness this billion-year anomaly and at the Cliff Mine area near the town of Phoenix. The Flow – called the “backbone” of the Keweenaw Peninsula - and can be seen up to fifty miles away and appears as a high ridge.

Of course, this is just a nutshell version of the complete story. If you wanna know a LOT more, check out this video. Some photos are below!

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