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IGS Maps Show Iowa Counties What Lies Beneath

Posted on January 5th, 2016

by Shianne Fisher

In this age of Google Earth, it’s hard to imagine a time when our world was unmapped and unknown. Today, with the touch of a screen, we can get directions to almost anywhere. However, it’s one thing to know where you are versus what lies under your feet.

“Geologic mapping is sort of becoming a lost skill set,” says Stephanie Surine of the Iowa Geological Survey. However, thanks to a U.S. Geological Survey program called STATEMAP, geological mapping has become a national priority. Surine, who serves as Iowa’s program coordinator, says the USGS ultimately wants the entire country mapped.

A digital copy of William Smith's Geological Map of England and Wales and Part of Scotland.

A digital copy of William Smith’s Geological Map of England and Wales and Part of Scotland.

And once, it was. The first geologic survey of the United States—published in 1809—was by geologist William Maclure; the map covered almost every state in the union at the time and took two years to complete. Of course, he’s not the only early geologist to create such a detailed geologic map. Maclure’s map was anteceded by that of William Smith, known as the “father of English geology.” His map spanned all of England, Wales, and part of Scotland; it took 14 years to complete.

Aside from being larger than Maclure’s map, Smith’s was also more detailed. Smith is credited with associating geologic layers (strata) with certain fossils, as well was putting forth the idea that strata are laid down in a predictable sequence—concepts commonly taught in geology today, says Surine. “But for the first person to go through the process of figuring out how this all works, wrapping his mind around this 3D problem, was a big deal,” she adds.

Nov. 15 marks the 200th anniversary of Smith’s Map that Changed the World, as Simon Winchester titled it in his bestselling book. The map recently gained renewed fame among geologists, as an original “lost” copy of the map was found in the Geological Society of London’s library. The society has planned events all year to celebrate its rediscovery and restoration.

The lost copy is one of just 70 surviving copies from the original 370 6-by-8-foot maps. The copies—colored by hand—were printed in 15 sections using the intaglio (copper plate) method, each folded into six panels. For the map to be so well-conserved means something to Giselle Simon, conservator at the University of Iowa Libraries.

Simon notes that map preservation and conservation primarily has to do with the substrate, or paper. She adds that as paper went from handmade to machine made, it lost its quality. “We see papers from the early 1990s that are what I call crispy critters,” she says. “So if we think about the William Smith map, it was probably in pretty good shape.” It was, thanks to 50 years of color-preserving darkness.

The creation of this Iowa bedrock map was an important milestone for the state.

The creation of this Iowa bedrock map was an important milestone for the state.

Today, neither mapping nor printing requires as much effort. “We have the benefit of time that we can get from point A to point B a lot faster,” Surine says. “We know where we’re at on a map already because those maps have already been produced.” Nonetheless, each map requires a host of data to collect and interpret. The goal, she adds, is that each new map is more detailed—and hopefully more accurate—than the last.

State Geologist of Iowa Bob Libra says that the future of geologic mapping looks increasingly to the third dimension to improve accuracy. “Whether 3D or conventional, these detailed maps have helped Iowans to assure sustainable supplies of clean groundwater, assess subsurface hazards, and develop needed mineral and energy resources,” Libra adds. A recent example is Cerro Gordo County, which is working to improve drinking water safety, map vulnerable groundwater, and develop best management practices, thanks to IGS findings.

Currently, the IGS is turning its STATEMAP efforts to Mitchell County. To learn more about the project, visit

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