SPRING GREEN, Wis. — Untouched by the last glacial ice age, the Driftless Area includes 10,000 square miles of geologic wonder that meanders throughout northeastern Iowa, southwestern Wisconsin, northwestern Illinois and southeastern Minnesota.

If you live anywhere in the Telegraph Herald readership area, you’re right in the heart of it.

Underneath the scenic landscape of rolling hills, undulating valleys and high-rise bluffs that surround us, you’ll also find caves, mines and tunnels just waiting to be explored.

ARTICLE CONTINUES BELOW ADVERTISEMENT

Spelunking is the hobby of exploring caves, cave systems and other subterranean sites.

The National Speleological Society, a nonprofit that focuses on the collection of underground data and the conservation of caves, has more than 10,000 members. The organization estimates that there are thousands more who explore caves as a recreational activity and that more than two million people in the U.S. visit caves every year.

Spring Green author Doris Green’s books, “Wisconsin Underground” and “Minnesota Underground” can guide you to some of these hidden (and not so hidden) natural creations. Green’s books also highlight some Iowa locations.

“I think they’re overlooked too often,” Green said. “People don’t realize that even now (with the pandemic), there are still many things they can do outside.”

Green first wrote her “Underground” books in the early 2000s. She found her co-author for the Minnesota book, geology professor Greg Brick, while doing research for her first book on Wisconsin. The second edition of both books were released in 2019.

“Greg wrote the foreword to my first book, and then we wrote the Minnesota book together,” Green said.

Brick, who has written extensively about caves and cave history, also has written a book on Iowa’s underground locations.

“The general knowledge about the Driftless Area has really exploded,” she said. “There are more educational exhibits and museums focusing on this area than there were 15 or 20 years ago.”

Green’s interest in the Driftless Area underground began during her childhood, when her family visited Cave of the Mounds in Blue Mounds. She was 9 years old.

“It just made this enormous impact on me,” she said.

Cave of the Mounds, 25 miles west of Madison, is what is known as a “show cave,” a cave or series of caves that have been developed with walking trails, handrails and lighting that make exploring easy.

“You really don’t need to worry about very much except for maybe a light jacket,” Green said. “The operators will provide a hard hat if you need one.”

The opposite of a show cave is a “wild cave,” a natural landmark formation that has remained relatively untouched. It might be open for exploration, but you generally are on your own, without any kind of guidance. And it could provide some challenges for beginners.

“If you’re going to any type of wild cave, you’ll need to bring your own equipment,” Green said. “It’s a good idea to bring one or two light sources, a helmet and good hiking boots.”

The average temperature inside most caves is approximately 50 degrees, so Green said a jacket is a must, even during the height of summer.

Green added that if you’re determined to visit a wild cave, those in state parks would be a good place to start.

“(A lot of) state parks and trails are open,” she said. “You can get to some pretty interesting sites without a lot of challenging hikes. And for a family looking to explore, wild caves in state natural areas are great.”