“The Last Frontier”
(2,440 Words)
(A
feature written in collaboration with
“Take
nothing but pictures,
Leave
nothing but footprints,
Kill
nothing but time.”
These words are gospel to cavers and a slogan on the Wisconsin Speleological Society’s web site, indicative of the concern local cavers feel for one of Door County’s least known natural treasures—its caves. As development encroaches and contaminants filter into groundwater near caves, the need to protect these geological formations increases. During a recent roundtable discussion, three members of the Wisconsin Speleological Society related their introduction to caving, shared important facts about caves, and explained why conservation of caves is so vital.
The Wisconsin Speleological Society (WSS) is a non-profit organization formed to promote “the initial discovery, exploration, study, research and protection of caves, their history and biota,” Gary Soule said. Supported by membership dues and private donations, the WSS publishes a monthly newsletter called “The Hollow Earth News” and an occasional research publication entitled “The Wisconsin Speleologist.”
Senior member and historian, Gary Soule, discovered a passion for caving in April 1961, while touring Kentucky’s Mammoth Cave, and joined the Wisconsin Speleological Society in 1971.
He and Buzz Davis met during a public tour of the now inaccessible steam tunnels in downtown Sturgeon Bay in 1984. A short time later, Buzz joined the WSS and now plays an instrumental role in repairing cave gates. He acquired aluminum from a local shipyard to fix a rusty gate at the Dorchester Cave and is handy with a tractor, when necessary.
Like Davis and Soule, geologist Bob Bultman’s first cave descent ignited a fascination for cave exploration after touring Maribel and Mammoth Caves with his dad, Dave Bultman. In August 1986, he happened upon WSS members mounting a gate on Horseshoe Bay Cave, toured it, and then joined the society himself, at the age of seventeen. Now the Cave Conservation Chairman, Bultman remains one of its most vocal advocates.
A fourth society member, John Kellner, could not attend the discussion. He is, however, pivotal to the group and to Door County, since he owns the land on which Paradise Pit Cave lies. After this cave’s discovery on July 20, 1968, Kellner purchased the property in 1969, then lamented to Soule that he’d bought “hollow land.” But, before long, he, too, caught the caving bug, which encouraged his first descent that same year. Kellner heads the Cave Owner Relations Committee.
According to Bob Bultman, “Groundwater forms caves.” When rainwater falls from the sky, it contains a slight acidic content that mixes with the acids from rotting plants, upon reaching the ground. This rainwater then percolates through fractures in carbonate bedrock, such as limestone or dolostone, dissolving the loose, weak rock. After millions of years, arching chambers and passages remain. This type of landscape is called a “karst” terrain, which means hollow.
We may take this process a step further to explain how cave formations occur. This acidic water contains a high concentration of minerals from the dissolved bedrock. When it encounters the roof of a cave, it seeps inside, drips, evaporates, and leaves a ring of calcite that gradually forms stalactites. Stalactites average only 1” of growth per 100 years. A similar thing happens on cave floors, where mineral rich water drips and deposits calcite that builds up into stalagmites. When water pools, the minerals it contains may deposit on the outer edges, causing them to spread out into other formations that resemble lily pads, known as “rimstone dams.” If stalagmites and stalactites grow together, they form columns.
Door County’s caves formed when rainwater dissolved its compact, dolostone bedrock, over time. Dolostone contains a lesser concentration of calcium, which accounts for one reason caves in this area are smaller. Water also influences the formation of caves; the more water that flows through a karst system, the more opportunity it has to dissolve bedrock. Besides bedrock thickness, calcium amounts, and water, climate temperature inside a cave also affects its formation. The average temperature for a tropical cave is 70 degrees, while the average temperature for a Door County cave is 46 degrees. Warmer climates spawn larger caves because warmer temperatures decompose plant and animal matter faster, which is why mammoth caves, the size of a river, exist in the tropics.
Glaciers sometimes interrupted the formation of caves. With their erratic tendencies to build up and later recede, glaciers often crushed or filled caves, leaving deposits of glacial till (debris) behind when they melted. This glacial till accumulated, often plugging up sinkholes and obscuring cave entrances. For this reason, many caves and cave passages in Door County lie undiscovered, hidden from view by glacial sand or rocks. Knowing this, many diehard Wisconsin cavers carry small shovels and hand tools as part of their required gear. “Digging into a hidden cave passage is a thrill. It’s like exploring the ancient pyramids,” quipped Bultman.
Door County is a karst terrain, characterized by sinkholes, caves, and underground drainage. “People often don’t realize that…Door County bedrock has many hollows, and that has huge implications for groundwater movement and contaminant movement into the groundwater,” Bultman said. “Caves are the primary conduits for groundwater flow,” so it stands to reason that there are environmental issues involved here.
If household contaminants are not properly disposed, we may create groundwater flow problems and contaminate wells. Since sinkholes and caves are in direct contact with groundwater, improper dumping into sinkholes endangers groundwater. Farm and lawn runoff, as well as detergents and other contaminants, pose a significant risk to groundwater and caves. Some people believe that this pollution caused some of the recent closings of our county beaches because groundwater flows to lake outlets.
The WSS hopes to pass legislation to protect caves that will also protect groundwater. They advise us not to build near sinkholes or caves, but, if we discover one on our property, they encourage us to contact Bob Bultman or Gary Soule for advice or free inspections. Bob may be reached at (920) 839-9938. Gary’s phone number is (920) 743-6488. The society also advises proper gating of caves, to prevent the danger of falling and to prevent human trespassing. The gates should, however, allow open access and protection for bats.
The Wisconsin Speleological Society is currently proposing expanded legislation that is similar to cave protection laws in other states. Currently, only caves or rock shelters that contain ancient petroglyphs or pictographs (rock art) may garner state protection. .
The state did, however, develop a water quality program that benefits sinkholes and karst aquifers. Under this program, the Soil & Water Department enforces certain regulations to prevent water runoff in development areas and farm fields under cultivation. These regulations remove some “marginal” farmland from production and also create easements in buffer strips to prevent sediment and chemicals from contaminating sinkholes. Society members caution that, ideally, we should preserve the karst area in its natural, vegetated state. Karst terrain is delicate, and people need to respect this. “Caves are not the problem—it’s man and how he treats them,” Soule said. “If man wants to treat them with disrespect—to allow contaminants in, then they become a problem.”
The Wisconsin Recreational Use Statute protects landowners from the liability of natural features in the landscape, including caves. Its basic principles hold that the natural features of a cave cannot be used as liabilities on an insurance claim. For example, if a person enters a cave and then twists an ankle while crawling through it, the injured person cannot hold the property owner liable for the accident.
Contrary to popular opinion, caves are very stable because the weak rock dissolves away. In fact, during an earthquake you are often safer inside a cave than in your own home. Caves rarely collapse and, if you know what you’re doing, they are not dangerous. It is important to note that, to date, no one filed any cave liability claims with the Wisconsin Recreational Use Statute. This further lends strength to the argument in favor of broader cave legislation and cave inclusion under an insurance company’s policy.
Why Caves are Important
“Caves are much more than just holes in the ground,” Soule said. One important purpose is to act as “hibernaculums” or resting places for bats. Bats are important parts of the ecosystem, since they reduce insect populations.
Shrews, skunks, bears, raccoons, foxes and porcupines may also rely on cave entrances as places to hibernate. Since the first 100 feet of a cave aren’t as dark as its interior and are used by hibernating animals, they are called “twilight zones.”
“Caves are a repository for bones…and paleontological evidence,” Bultman said. In June 1986, on Brussels Hill, cavers unearthed the oldest known bone discovery in a Door County cave, which dates back more than 2,000 years. During this dig, they uncovered the remains of a deer that was 25% larger than modern-day deer. They also found a species of snail and shrew, which normally inhabits more southerly locations, and many other peculiar bones. These bones need more analyzing by paleontologists, to identify their remains and pinpoint the time period their burial occurred.
“Caves are time capsules. They’re windows into past climate,” Bultman also said. Over time, when animals and plant life fall in, they compact and form layers of debris that paleontologists may sift through and analyze, to determine past weather influences.
Caves house rare and unusual rock formations that can never be replaced.
Some of the public parks on the Peninsula contain small, accessible caves, but most caves in Door County are on private property. Many are gated to control access. Never go caving without the consent of the landowner, as caving without permission is trespassing. You may contact Bob Bultman for more information regarding potential cave tours.
You may also contact Gary Soule for details about Ledge View Nature Center, which is a great educational facility for children and offers public cave tours. Some Sturgeon Bay fourth graders have already taken field trips there. Located two miles south of Chilton, society members hold meetings there, as well. Professional naturalists offer tours through three different caves, with varying levels of difficulty. If you allow enough time, there is a free, 3-level 60’ observation tower, cave displays, live sturgeon, and imitation Niagara escarpment. Any school can attend by contacting Ron Zahringer, head naturalist for Calumet County Park system. Ledge View’s phone number is (920) 849-7094. Their caves open for tours during weekends, between May and November.
Anyone wishing to see a “full-fledged show cave” is encouraged to visit Cave of the Mounds, near Blue Mounds, west of Madison. This is the only National Natural Landmark Cave in Wisconsin. Call Gary for more information.
So, you want to go caving? For advice concerning safety precautions, proper equipment and clothing, and guided tours, contact a WSS member.
“In Door County, definitely, caves are the last frontier,” Soule said. “Any one of us, with some simple clothing and a little bit of luck, might be able to move the right rock and see some virgin or unexplored land that no one knew existed before. Who knows—a cave might even be under your house.”
Of the 400 Wisconsin caves under
the WSS umbrella, 10% of these charted caves exist in Door County, and members
suspect there might be forty more. Shown
on a map, the highest concentration of caves appears near the escarpment,
Brussels Hill, and around Southern Door High School
Horseshoe Bay Cave, mentioned below, is renowned for cutting the deepest passage through the earth’s bedrock, traveling laterally across the landscape. The hill rises higher above the cave as you penetrate the Niagrara Escarpment’s interior. It is 129’ from the surface to the underground river that WSS members affectionately call “The Mississippi River” (not to be confused with the Mississippi of Huck Finn fame), to the top of the escarpment above. This river is deep inside of Horseshoe Bay Cave and was not discovered until September 1978. Divers dove at the far end of this river and emerged 52 feet later, to find an air-filled passage. Extending quite a distance through Horseshoe Bay Farms property, the cave seems to go on forever but not clear through the county. Evidence suggests that no one explored this entire cave in over 600 years.
Four longest caves in Door
County:
Horseshoe Bay Cave or Tecumseh Cave--about 2 ½ miles south of Egg Harbor--is over 3,103 mapped feet long and also the second longest mapped cave in all of Wisconsin. Many of the passages are wall-to-wall water and have as little as 4” of airspace in some parts.
Paradise Pit Cave--over 1,791 feet long--the 4th longest cave in Wisconsin, with four entrances
Dorchester Cave--the only one within Sturgeon Bay city limits--345 feet in length and has two different sections
Bear Cave in Fish Creek--156 ft. long
Three deepest caves in Door
County:
Brussels Hill Pit Cave—over 92 feet deep
Crevice Pit Cave—2nd deepest, over 69 feet deep--going down from the entrance
Paradise Pit Cave—34 ft. deep--3rd deepest
Three highest ceiling heights:
Big Room in Horseshoe Bay Cave—55 ft. high—largest cave room in terms of volume in entire eastern half of the state
Waterfall Room—Horseshoe Bay Cave near Egg Harbor—50 ft. high
H.H. Room or Walled Room in Horseshoe Bay Cave—40 ft. high
Most difficult cave to enter:
Eagle Cave in Peninsula State Park—30 feet straight up near Eagle Bluff--which requires special climbing techniques to enter
Tightest passageway—Paradise Pit Cave’s Cadillac passage--a notorious passage on the far north end of it
Two caves in county with
buildings over them for an entrance:
Dorchester Cave
Open Door Pit Cave behind Southern Door High School
The inside of a cave is 40% darker than the darkest, moonless night you’ll ever experience in your lifetime.
Most caves are at least 60,000 years old and require more study by geologists, to unravel the secrets that still lay hidden within their walls.
Ø
Never cave alone. Ideally, go in groups of three.
Ø Notify someone where you’re going and when you might be back
Ø Make sure you have proper equipment and clothing, such as coveralls, gloves, and ankle high boots with deep treads. Wear a hard hat and take three sources of light
Ø Expect to get muddy and wet and dress for these conditions.
Ø Add an extra hour or so to someone’s estimated return, since time flies when you are experiencing the wonders of a cave.