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Kettle Holes
Those perfectly round holes formed in solid granite rocky outcrops; the remains eons ago of mountains. The KETTLE HOLES can be seen in various places along the Minnesota River and valleys. What caused them and how were they formed?
Thirteen to 15,000 years ago, a huge glacier hundreds of feet thick covered much of the North American continent. It reached as far south as central Minnesota. In the ensuing year, the climate warmed causing that immense glacier to melt and become Lake Agazzi. Larger than all of the great lakes and hundreds of feet deep.
The outlet flowed south and east cutting and forming our present Minnesota River and Valley. Imagine a rushing, roaring river hundreds of feet deep and up to five miles wide carrying everything in its path.
An example of its power can be found on the courthouse lawn in Granite Falls, Minnesota. This huge granite stone was dug up on the site of the law enforcement center. The force of falling water and time can be seen in another giant granite store. Two sides are sloped and worn. It rests on the south lawn of the Granite Falls Supper 8 Motel.
KETTLE HOLES were formed when jagged stones carried by the river’s current struck a depression in the bedrock. As time passed, the depression became a hole trapping the stones that fell in. The force of water caused the stones to rotate, thus shaping a KETTLE HOLE. Some small, other huge, from smaller than a gallon pail, to a bushel basket in size. One huge KETTLE HOLE in Granite Falls had to be fenced off to prevent cattle from accidentally falling in and unable to get out.
An example of a KETTLE HOLE can be done. Place a small, walnut sized stone in a water pail, with a garden hose on full pressure – watch the stone madly revolve around the pail. Stones have been found in the Granite Falls area; perfectly round granite stones from golf ball to basketball sized; over a hundred pounds.
John W. O’Neal
Granite Falls, MN
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