The Minihaha Archives

How do Bat's fly in the dark? How do Dolphins navigate underwater? How do you Hunt for Red October?     SONAR.

Technically speaking, Sonar is an acoustic, echo location technology. High frequency pulses, or pings, are chirped and the animals listen for echo's bouncing off solid objects like Bugs or Fish. Boats use these pings to locate submarines or the ocean bottom. It's the same effect you get when talking in a gymnasium, echoes. How long the echo takes to return tells us how far away, or deep, an object is.

In 2003, we started using Sonar to generate 3 Dimensional images of the pond bottoms in The Buesching Bog. These ponds are the result of 50 years of excavating peat and topsoil. They're generally shallow, from two to six feet deep, and the bottom is lined with a mucky soil called Marl. It's this layer of Marl which contained The Buesching Mastodon, discovered by Dan Buesching in 1998. Our Foundation has a Lowrance Sonar system capable of taking depth soundings and transferring them to a Laptop Computer. The resulting images are a 3D map of the pond bottom, or in Geek Speak, a Bathymetric Survey.

Most lakes in Northeast Indiana are less than one hundred feet deep. Depth or Fish Finders include transducers strong enough to reach the bottoms of these lakes. We're using a high powered transducer designed for ocean going vessels and can measure depths up to 1,800 feet. For those into "more power", this transducer generates 8,000 watts of acoustic power. When it generates a ping, our boat shakes. Why would we use this overkill transducer in a six foot deep farm pond? We're evaluating it's capability to penetrate into the Marl pond bottom in an attempt to locate the large missing bones from The Buesching Mastodon as well as other submerged animals. Our GPR (Ground Penetrating Radar) system, mounted in a raft, is capable of penetrating the Marl, but costs 10 times as much as the best Sonar System. We're evaluating Sonar as a low cost alternative for others to use instead of GPR. Our test also show that GPR works well as WPR (Water Penetrating Radar). Who knew?

To the left is a Sonar Contour image of the 2 acre pond bottom which contained the mastodon. Deeper water is dark blue. Click on the image for a larger picture.

To the right is The Minihaha Foundation Paddle Boat of Science. The GPR is in the raft on the front. Click on the image for a larger picture.

Equipment mounted in the boat includes the GPR, Sonar System, Global Positioning System and a Laptop computer to collect data from all three devices. A technological marvel. The Buesching Bog contains five different ponds. All may be homes to Ice Age Animals just waiting to be discovered. The underwater hunt is on. PING....

For more information contact John Weddell, johnweddell@att.net.