Mysterious Triangle Holes
Found In Rocks
By Brent Zell
Watertown Public Opinion
Neighbors Editor

CORONA - The mystery starts with, of all things, Play-Doh. By using the clay-like children's plaything in a demonstration, Judi Rudebusch aims to make a point. She plunges the pointed end of a four-sided star drill bit into the Play-Doh and twists it. The hole, of course, is round. Then she sticks the edge of a chisel into the Play-Doh to show how it leaves a hole with edges.
The point of the exercise is to show the difference between round-cut holes and the edged holes that have been been found in hundreds of other rocks throughout the upper Midwest over the years and have spawned all kinds of historical theories. It's also the same type of hole that Rudebusch has found in rocks around Wilmot and Corona. Lay a quarter next to one, and one can see the difference in shape.
And not just one rock or a few. She's found them in 52 rocks throughout the Whetstone Valley.
"Those holes are there for a reason. What does it tie into?" she asks rhetorically.
It wasn't a hole in a rock that got Rudebusch interested in this mystery. Rather, it was a horn.
When she was young, Rudebusch played near her dad's house and remembered coming across a rock with an unusual look to it. A few years ago, she went back to the land to look for the rock. There it was: a chunk of granite peeking out of the weeds, with an indentation right on top. The marking looks to be in the shape of an animal's horn. It could be water erosion, but erosion would normally go all the way down the rock. The indentation curves north at the end.
Piqued by the uniqueness of the shape, Rudebusch contacted Marion Dahm of Chokio, Minn. Dahm has spent the last few decades seeking out unusual markings and holes in stones across the upper Midwest. He came over and was excited by what he found. He also told Rudebusch to go search the hillsides of the area for more unusual markings.
Sure enough, Rudebusch began to find rocks with the triangular-shaped holes in them. In her first year of searching the fields around the Corona area, she found 17 rocks with similar indentations. More came as more people began to tell her of similar indentations on their properties. As the number grew, so did her interest.
"I just want to keep finding more," she said. "I wanted to see what the next one looked like." The discoveries have more in common than just a certain type of hole shape.
The elevation of each rock is estimated to be between 1,150 feet to just over 1,200 feet. The rocks are usually deep in the ground and on the side of a hill - away from flat, farmable land. The holes themselves are not exact sizes, ranging from around 3/4 inch in diameter to 1 3/8 inches.
As mentioned earlier, there are hundreds of rocks with similar holes across the Great Plains. With the discoveries have come the theories as to why the holes are there. A popular theory is that the holes were drilled to insert dynamite to blast the rock apart.
But here is where the questions start coming up for Rudebusch. From her research, dynamite was about 1 1/2 to 2 inches in diameter - too big to fit in the majority of the holes found. When making holes for dynamite, a star drill was used, which makes a round hole, not one with edges. Plus, a common way of blasting rock in this area was by a process called mudpacking. Farmers would lay one or two sticks of dynamite on the rock and cover it with mud, then light the fuses.
Then there's the location of the rocks themselves that make that theory cloudy.
"There wouldn't be a real good reason to go out of your way to move them," said Rudebusch.
Another theory was that holes were cut into the rocks to make foundation stones. But according to people that Rudebusch has talked to who know about how things like that are done, a number of holes are cut into a rock to make foundation stones - a better edge is made that way.
The rocks Rudebusch has found have a single hole. Yet another theory is that holes were made for geological core samplings. But the device used to make them has a round tip, and wouldn't leave edges on the inside of a hole.
One theory that Rudebusch said would be easy to assume is that the rocks were used as mooring stones.
The rumors of mooring stones have been around the upper Midwest for decades. Legend has it that during the first half of the last millennium, ancient Vikings made their way into what is now the Great Plains and set up settlements. They cut holes in rocks near waterways to establish poles in to tether their ships to.
It's an assumption that has flared up again with the recent discovery of a rock near Kensington, Minn., that may bear inscriptions written in ancient Scandinavian lettering. That area is already famous for the Kensington Runestone. The stone, supposedly discovered in 1898, has etchings on it that some people think tell a story of the deaths of Viking explorers in west-central Minnesota in the 1300s.
That theory has never been proven and has its fair share of nay-sayers in the archaeological community.
Even with three years of walking fields and tons of research to go on, Rudebusch said that she isn't subscribing to any particular theory on what the holes represent.
"There's not enough evidence to firmly sew down any theory," said Rudebusch.
A geologist from Vermillion came out and looked over the stones on Monday, and he determined that if nothing else, the holes definitely were not made naturally. Rudebusch said that more geologists are on the way, and that she's been in contact with the state's archaeological office.
It is a consuming hobby for Rudebusch. She said she doesn't possess the background to try and prove this. It's not a cultural thing for her. It has more to do with her enjoyment of history - and the mystery that these rocks present.
"It just swallows you up," she said. "It does wake you up in the middle of the night, thinking."
©Watertown Public Opinion 2001


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