Tearing up the road collecting data

The ‘mobile ground magnetometer’, although a simple adaptation, was a magnetic profiling breakthrough.  Never before had the USGS been able to record tens, even hundreds of miles of magnetic field data at ground level in a day. We traversed highways, small roads, even little trails through the brush.

USGS Mobile Ground Magnetometer

All sorts of people came to see us operate. Professor Schwartz, from the University of Minnesota, rode with us one day, fascinated, as our chart drive drew a red line on paper, depicting the magnetic field.

“Oh, look at her go!” he cried, as we crossed a culvert in the road. The chart needle dipped and swung, clearly drawing the magnetic field of the culvert, just as theory predicted it should.

Dr. Jim Balsley, head of the Geological Survey geophysics branch, flew out to see our new toy. He suggested some changes to my recording method that would require me to control the traversing using both hands and both feet, — “and then while you’re at it you can stick a broom up your (censored) and sweep out the truck!”

A Ph.D. student from Ghana named John Cudjoe, traveled with us for several days. He was a great character, with a wonderful outgoing personality. He was a celebrity everywhere we stopped.  Later on, John became the chief of the Ghana Geological Survey.

Gordon Bath had worked with a man who owned a resort at the end of the ‘Gunflint Trail’, a road that led from Lake Superior into the Boundary Waters Canoe Area of northeast Minnesota.  The gentleman had done magnetometer traversing using traditional instruments.  He wanted a traverse across the Gunflint Iron Formation, which crossed the Gunflint Trail a few miles from his resort.

He drove ahead of us and stopped where he wanted our traverse to start, then drove ahead to where he wanted the traverse to end.

As he drove away we followed him, stopping behind him when he again stopped.

He came back to our truck, puzzled.  “Having trouble with the equipment?” he asked.


“Why didn’t you run the traverse?”

“We did.”

“You mean, that’s all there is to it?  Can I see the results?”

I tore the chart paper out of the recorder and handed it to him.

“We’ve had the magnetometer running since we left your place.  Here’s the field profile from your resort to this point.”

The amazement on his face was really gratifying.

Bill Curran, a local college student that drove the magnetometer truck, and I became great friends. We traversed together all day, ate together, and shared evening spare time together when we spent overnights on the road.

In the summer of 1957 we traversed most of the roads of geological interest in central and northeastern Minnesota.

In the summer of 1958 we traversed roads in northern Wisconsin and upper Michigan.

In the spring and summer of 1959 we moved our base to the USGS regional headquarters in Menlo Park, California.

More of that in the next post.

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