The Keweenaw Peninsula has become known for rugged terrain and beautiful locations to explore. But the Copper Country could not include miles of cliffside trails, diverse beaches and stunning waterfalls without a little geological shakeup more than a billion years ago.
The peninsula formed when volcanic basalt cooled following activity that uplifted the midcontinent rift, creating the foundation for today’s dramatic landscape.
“Usually it’s a combination of physical forces that are deforming the rocks and then other forces of nature that erode the rocks and sort of sculpt those rocks into the patterns that we see today,” said James DeGraff, research professor of geological and mining engineering at Michigan Technological University.
The last major geological event to significantly impact the terrain occurred when glaciers expanded and retreated over thousands of years. The most recent glaciation ended approximately 10,000-12,000 years ago when ice sheets from Canada carved the landscape by eroding softer rock and leaving harder formations standing.
The geological structure creates distinct topographical zones across the peninsula. The harder lava flows containing native copper form the spine of the peninsula on the northwest side.
“And as you go toward the northwest, toward Lake Superior, you gradually lose elevation and then eventually you’re at lake level. But in the other direction, when you cross the Keweenaw Fault, which separates those lava flows from a rock that’s called the Jacobsville Sandstone, the Jacobsville Sandstone is much softer. And so it tends to get eroded down. You see a lot of swampy ground there,” DeGraff said.
From Canyon Falls in Baraga County to Montreal Falls at the tip of the Keweenaw, many visitors will enjoy hiking to waterfalls this summer. The region’s waterfalls showcase the dramatic geological contrasts that define the peninsula’s character.
At some locations, evidence of the area’s mining history remains visible. Old copper exploration tunnels, called adits, can be found near the Houghton – Douglass Falls, carved into the basalt rock formations that attracted miners more than a century ago. DeGraff’s students have studied the bottom of the falls to find the Keweenaw Fault and Jacobsville Sandstone downstream.
The Houghton – Douglass Falls have become very popular over many years. Previously the falls were located on private property. In 2018 the Michigan DNR began designing plans to make the state’s tallest waterfall more publicly accessible. Additional work expects to complete a trail, observation platforms, and a veterans’ memorial after work in 2027.
“If you go downstream from that adit maybe 50 or maybe 100 yards, that’s kind of where the contact is. It’s not something that you can put your finger on,” DeGraff said, describing the geological boundary between different rock formations.
While many notable waterfalls occur near the fault line, not all are fault-related. Leaving some mysteries for geologists to research, such as at Queen Anne Falls near Copper City.
“But if you follow that down maybe half a mile, you’ll get to a waterfall called Queen Anne Falls. And that, I don’t really know why that’s there. I mean, again, it’s going to be hard rock upstream, softer rock downstream, but I’m not quite sure exactly what’s going on. It is within the lava flows that are called the Portage Lake Volcanics,” DeGraff said.
The geological complexity of the region continues to intrigue researchers and visitors alike, offering both scientific insights and recreational opportunities for those exploring the Copper Country’s natural heritage.
Visit Keweenaw officially starts Waterfall Week in the Copper Country tomorrow, featuring events over four days. Those interested can learn more about waterfalls and recreation in the Keweenaw Peninsula online.
