Low-Level Flights to Assess NE Iowa Mineral, Water Resources

By Orlan Love, Reporter

WINNESHIEK COUNTY, Iowa - Residents of Winneshiek and Allamakee counties needn't be alarmed if they see low-flying aircraft with dangling instruments in the weeks ahead.

It is only scientists studying the rock layers deep beneath northeast Iowa and southeast Minnesota, according to the U.S. Geological Survey.

A low flying airplane and helicopter with auxiliary instrumentation will be used in flights beginning as soon as Sunday and continuing through January, the USGS said.

The data will be used to generate 3-D subsurface maps of the region's water and mineral resources.

"The USGS uses the latest technology to find new sources of" clean water and valuable minerals "even when buried deep beneath the Earth's surface, and places that information in the public domain to benefit all Americans," said USGS Director Marcia McNutt.

The survey area is thought to be part of the 1.1 billion year old Midcontinent Rift, which stretches across much of the central United States. The rift includes large volumes of iron and magnesium-rich igneous rocks that, in the Lake Superior region, contain deposits of nickel, copper and platinum.

USGS scientists plan to use the new geophysical data to help determine if there is potential for similar resources in the survey area. A secondary goal is to evaluate water resources beneath the sandstone and limestone layers.

Large electromagnetic and magnetic instruments will be suspended on a cable beneath the helicopter. The airplane will carry gravity gradient instruments.

Because different rock types differ in their content of water, magnetic minerals and density, the resulting geophysical maps will allow visualization of the geologic structure below the surface.

None of the instruments pose a health risk to people or animals.

All survey flights will occur during daylight hours at heights between 100 and 500 feet. The east-west grid lines will be about a quarter mile apart, while the north south lines will be about 2.5 miles apart.
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