From Oct 2019 (left) to April 2020 the shoreline at Miami Park, Michigan, eroded more than 3 feet. Image: Michigan Geological Survey
By Genevieve Fox
While growing up in Michigan, I loved waking up early to the summer sun for a day of swimming and collecting rocks.
I remember looking out to the lake. I felt the rocks below my feet and admired the shimmers of gold and red sparkling through the water and the sound of the waves crashing. The beautiful rocks glistened like a pool of red rubies and orange topaz.
I collected rocks in an ordinary white sock from my closet and chose those worthy to take home.
Last summer, I visited the Upper Peninsula for the first time, excited that I could collect new rocks from Lake Superior. I got my rock sock and ran down to the beach as fast as I could. As soon as my feet touched the sand, I breathed in the freshwater air and stared at the rocks below.
The beach was filled with rock structures, walls as long as buses piled up on the shoreline.
They were man-made rock structures known as rock armoring.
They are put on Great Lakes shorelines to protect homes from soil erosion, said John Yellich, director of the Michigan Geological Survey, a state agency that promotes geological research.
These rock structures are made up of limestone and cement, and cost $2,000 per foot to install, Yellich said.
But rather than reduce erosion, the Michigan Geological Survey found these rock structures rapidly increase it.
When you put something on the beach completely different from the normal face of the beach you cause waves to react to that area differently, Yellich said.
When waves crash on a beach, the water flows on the sand into the lake, Yellich said. When you put these rock structures on the shoreline, the waves crash onto the rocks and the soil underneath the rocks erodes.
“It’s catastrophic,” he said.
The eroded soil flows back into the lake and doesn’t come back.
“The beach is gone,” Yellich said. “You eroded it away, just like taking a shovel and throwing it out to the lake.
“If there is no beach, visitors will have to walk on the rocks, possibly falling into a hole between the rocks, or walk through the water,” he said. “Walking on two-foot boulders isn’t fun.”
The most effective way to prevent soil erosion is not putting rock armoring on the beach, Yellich said. A technique to possibly help erosion is placing one or two wells on the beach to dewater the bluff, increasing the stability of the shoreline, according to United States Geological Survey.
Previous solutions like seawalls and groins, a hydraulic structure, have been proven to worsen the beach face, according to United States Geological Survey. Research continues.
Rock armoring techniques are still used today to protect the shorelines, despite conflicting research, Yellich said.
I envision myself back on the beach last summer. I open my eyes and see no sand -just piles of unalluring rocks stacked on top of each other. I glare at these stone revetments, my feet longing to feel the sand between my toes.
I don’t want my children to know a beach without sand.
I returned my rock sock to my top drawer in my dresser.
Genevieve Fox is a reporter for Great Lakes Echo.