Spring Valley Caverns


The story of our amazing discoveries. 2008-2009 by John Ackerman

Tyson Spring Cave, located in S.E. Minnesota, is a historically significant cave, which has captivated local inhabitants for hundreds of years. A major stream flows out of its remote picturesque entrance, located at the base of towering limestone cliffs. In recent times local inhabitants took great joy in venturing into the cave in makeshift boats. After 900 feet they were abruptly stopped where the ceiling sloped down to meet the water. I am sure hundreds of curious minds wondered what lay ahead, beyond this water filled passage.

In the 1980’s diving equipment and wetsuits were refined to accommodate cold water conditions and constricting situations. Several divers took advantage of this, and managed to dive through several sumps to find that a large cave system existed. The cave was so extensive and challenging that they never did explore the entire cave. In September 1987 Roger Kehret, Dave Gerboth and I managed to remove enough rock from the floor of the stream passage so that I was able to squeeze through both sumps by scraping my nose along the ceiling and moving forward ahead slowly through the several inches of air space available. I was traveling light, with only my wetsuit, helmet and extra flashlight. Donning the SCUBA gear provided more advantages, including agility.

Without any consideration for safety I went forward alone, into the expanding blackness. I seemed to be drawn deeper into the cave like a magnet. This place was alive and vibrant. The turquoise blue water ebbed and flowed over numerous calcite dams and collected here and there into deep cavities, some of which required me to swim across. The further into the cave I traveled the more astounded I became. The main passage became wider and taller, and as I crested a bus sized limestone block I found myself standing in a huge room with a sandy floor. After catching my breath momentarily I rejoined the main stream passage, where the formations grew in size and color. After traveling one mile through this labyrinth I was totally awestruck.

Eventually I came upon another sump, but again could only see several inches of air space, and so I decided to risk it once again. This almost proved to be a fatal error on my part because I actually became lost in this passage with my lips scraping against the ceiling. I meandered throughout the icy cold pitch-black passage, sniffing for a way out, any way out. My neck muscles were eventually so fatigued that they were almost unable to hold my lips to the ceiling. Finally I made the correct turn and popped out into the continuation of the huge cave passage. Hours later, after traveling almost two more miles through stupendous cave passages I turned around and made my long solo journey out. Along the way I was enthralled by the dynamics of the stream passage and understood my fate if it were to rain outside, causing the water to rise even one inch. Why I thought I could cheat death I will never know. Maybe it was because I understood that great discoveries involve great risk.

Three weeks later, with 3 fellow cavers trailing behind me I finally reached the “end” of the cave. I had been the first human to reach the far depths of this cave system and the experience had been etched into my very being.

I was 33 years old when I made that epic trip into Tyson’s Spring Cave, and it had remained seared into my consciousness ever since. For the next nineteen years time stood still in the cave once again. Very few cavers, including myself, dared enter the cave due to the nearly impossible entry point. Then in 2006, after reviewing old photos and trip reports of this magnificent cave system, I made an unyielding pledge that purchasing the cave and creating a safe man made entrance would be a top priority.

And so it would be. I successfully purchased the cave rights and created a 120’ deep access shaft into a safe spacious region in the cave.

My first priority was to hike miles through the cave, searching for additional segments. One dirt filled side passage, located just a few hundred feet downstream of the new entrance, appeared an interesting candidate. On Saturday April 12, 2008 Clay Kraus, Dave Gerboth and I were pulling sticky moist clay out of this lead in an attempt to follow it deeper ahead. The passage was narrow, and as I laid on my side, one wall was pressed against my back and the other wall almost touched my stomach. There was about 2” of air space above my head. I would reach ahead, remove a quantity of soil with my trowel and place it in a metal tray, which was pressed against my ribs. Then Dave and Clay would pull the pan back with an attached rope and dump the spoils alongside the huge cavernous stream passage. Then I would pull the empty pan back using the other end of the rope and repeat the process over and over. I had gained 25 feet and could see the passage was opening up ahead and was excited at the possibilities. It was around lunchtime, and I figured that was why the tray was not being pulled back when I repeatedly shouted “pull!”

After a short time it was apparent that something more exciting was happening back behind me. I slid back out of the passage and as I entered the main passage I saw Dave grasping what appeared to be a large stout shaft. He had been using it to dig out a spot flat enough so he had a firm work platform. I immediately inquired about what he had found, and he responded that it was probably an old leg from a cast iron stove. I snatched the sixteen inch long “leg” from him, and washed it off in the stream, located just a few feet away. At once I recognized it as an ancient bone and blurted out “this is an ancient bone, not a cast iron leg!” At the end of the day I carefully stuffed it into the top of my wetsuit and transported it topside, where Clay snapped a photo of me holding the prize. I had hoped it wasn’t just a cow bone.

I posted a photo of the bone on our caving chat line but nobody had a definitive answer. On April 22nd I brought the bone to David Mather at the St. Paul History Center. He immediately identified it as part of an elk or moose antler but could not pinpoint the exact species. He was so enthralled with the specimen that we went directly to the St. Paul Science Museum and met with their staff. We carried the bone down to the lower level, past dozens of huge storage cabinets containing thousands of old bones, until finally reaching the workshops where old arrowheads and assorted bones were being pieced together and identified. The well seasoned staff was simply in awe of the bone, and their enthusiasm grew more each time a comparison was made to their collection and found to be different. Finally they gave up and stated that the antler was so unusual that it should be sent to the Illinois State Museum, the final authority on ancient bones. I packaged it well and forwarded it to the assistant curator, Chris Widga.

On May 15 David Mather entered Tyson Spring Cave with Clay Kraus and I to inspect the discovery site. As he stepped into the cave he immediately snatched up a small bone he spotted lying on the stream bank. David was impressed with the splendor of the cave and commented that there could be hundreds of bones scattered throughout the passages. On the way out of the cave Clay also found a small bone, stuffed it into the top pocket of his coveralls, and climbed up the ladder to exit the cave. He tossed his coveralls over the top of his car, and later when he attempted to show David the bone he realized it had flown out of the pocket! After searching in vain throughout the immediate area Clay gave up, reached into the back of his car and handed David a consolatory bone he had in his car. David was not impressed with the raccoon bone and scanned the ground with serious intent. He quickly found it, held it up to inspect it, and proclaimed the bone to be an important ancient specimen. As David drove away I am most certain that he mumbled something like “these guys are clueless!”

On June 26 Chris Widga drove from Illinois to also visit the site. Chris has spent many hours in caves sifting for bones and was comfortable with the cave environment. Clay and I led him to the discovery site and watched as he took soil samples where the bone was unearthed. Iron deposits in the soil could determine if this was an ancient site. On the way out of the cave Clay noticed an unusual projection along the stream bank and inquired whether it had any significance. Chris said “probably not” and continued to scan the bank for bones, where he successfully located several. Clay was fixated on the unusual shape of the projection, and after a few moments unearthed it. Chris shone his light on it, washed it off in the stream and proclaimed that Clay had just discovered something incredibly rare, quite possibly part of a skull from a sabre-tooth tiger or American lion. He was confident that this discovery was as important as the antler, and couldn’t wait to return to the museum so he could make a positive identification.

In the meantime it was learned that the antler belonged to an extinct Stag-moose, (Cervalces scotti) an ice age solitary browser. Never before had any bones of such a creature been located this far north. This was a Minnesota first.

On July 5 Dave and I made a trip into Bat River Cave, a similar stream cave located in the same general area. This cave had been known for hundreds of years, but it was only recently that several of us dove the sump at the back of the cave and found the real cave system. I purchased access rights to the cave in 2007 and created a 60 foot deep entrance shaft. Now I surmised that this cave, in theory, should also contain ancient bones. Sure enough, I located and collected an assortment of bones along the main stream passage. Don’t know why I walked right by them before.

On December 28 Dr. Jay Kennedy, Javier Guzman and I traveled upstream from the man made entrance in Tyson Spring Cave searching for bones in anticipation of Chris Widga’s upcoming visit. Several weeks ago I had learned that the skull found last June was positively identified as a sabre-tooth cat, (Smilodon fatalis) and had been dated to 27,000 before present by the Rafter Radiocarbon National Isotope Center in New Zealand. The date was shocking, but even more profound was the fact that the nearest sabre-tooth cat remains that have ever been found were in northern Arkansas. This revelation sent shock waves through the scientific community. Another Minnesota first.

The pressure was on to notify the media, but I chose to wait until even more information could be obtained before making the stunning announcement. Jay, Javier and I collected 18 bones along the stream bank that day. I also retrieved a large bone that I had tossed aside some time in the past, thinking it was just a worthless cow bone. Turns out this bone was identified as coming from a large cat, perhaps the same 27,000 year old cat that was discovered about 1.5 miles downstream last June.

On January 10, 2009 Dan Pertzborn. Johan Ragner and I went on an exploration trip into Bat River Cave. This time we ventured upstream from the new man made entrance along the main passage referred to as the “Death Passage.” It takes three hours of sliding on your belly in the water, with less than a foot of airspace, before reaching another large section of walking cave. We collected about a dozen bones along this route, but when we reached the large section there were about 40 bones of varying sizes scattered on the floor. I was elated, and obviously well aware of their importance. All the bones were photographed and sent to the ILL State Museum. Can’t tell you why I didn’t notice them during our previous trip into the remote region. I think we had been concentrating on the bats and the wondrous formations.

On January 18 Jim Edberg and I traveled all the way to the upstream limit in Tyson Spring Cave and found a dozen bones. When I reached the tall dome at the “end” of the cave I noticed animal prints in the mud below the domepit. Could a small mammal survive the drop down a 75’ deep pit? Sure seems that way.

On January 21 Chris Widga returned to Tyson Spring Cave. Chris, Clay, Greg Brick and I decided to travel upstream from the new entrance. When we reached the domepit where I had preciously tossed aside the ancient cat bone Clay got busy scouring the floor for bones. He instinctively reached behind and under a large slab, feeling for artifacts with his hands. After a few moments he began to dredge up bone chunks, and then without warning he pulled up a large scapula. Chris immediately identified it as an ancient cat scapula. I set up my camera and had Greg photo document the grand occasion. I was almost numb with the thrill of it all. All of us hiked to the upstream “end” of the cave and collected another 20 bones. On the way out of the cave Chris stated that this cave was to be considered a significant and rare Pleistocene site.

On February 21 Matt Covington and I traveled upstream from the new man made entrance in Bat River Cave. We slid and pulled ourselves along the low wide sandy stream passage for about ¾ mile before eventually discovering a large passage. This trip took about 4 ½ hours but it was worth it. The passage we found measured 30’ tall x 15’ wide. Immediately upon entering the passage we began to see bones lying on the gravel floor. They all appeared ancient and were very large. After about 30’ the main passage became very narrow, but remained tall. It was not possible to follow it, so Matt and I climbed up about 10’ and made our way forward along the constriction. Matt was able to squeeze through the narrow slot and dropped back down into another tall room. Matt immediately saw a large bone resting in the center of the floor and gently moved it aside. Then he scanned the new area and discovered that it was possible to follow the passage back to where I was waiting through a lower stream tube. As he approached me I saw his light under the water in front of where I was standing. I was able to lower the floor enough so that his lips and nose could rise above the water and he could slide forward to join me. Then we both went back through this new route (which required us to immerse our entire heads in the water) and stood in the new room that Matt had discovered. At the end of that room was a 20’ tall waterfall that had a smooth steady stream of crystal clear water running down the front. The waterfall was covered in a thin film of white calcium, which made the water sparkle as it ran down the silky face. Matt and I were able to climb to the top, and found that there was a 10’ tall passage leading off into the blackness. We followed this for a distance, and eventually the ceiling became lower, which forced us to begin crawling.

I found an assortment of large bones here and carefully brought them back to the waterfall room and then through the low air spaces to the main 30’ tall room, where we packaged them for the trip out. One bone was astounding. It was one half of a 9” long jaw with intact teeth. This was the only bone found so far with intact teeth and I was giddy just imagining what it could be. I was able to transport all 11 bones safely through the long tortuous journey back to the surface with no damage.

Several days later the jaw was tentatively identified as an extinct Bison. I was more than happy. All told we have discovered a total of 175 bones. Most were found in Tyson Spring Cave and Bat River Cave, with a handful found in Goliath’s Cave and one in Spring Valley Caverns. I have been informed that our bone discoveries have been classified as the most significant scientific finding in any Upper Midwest cave. Case in point: Penn State lab has informed us that they were able to amplify and sequence DNA from the Tyson Spring sabre-tooth cat skull! This is a profound event, and may be the first time that DNA has been extracted from a North American sabre-tooth cat.

It will take years before all 175 bones are analyzed, and some of the bones will no doubt reveal even more astonishing firsts. In the meantime, I released the news to the print media, where it received broad front page coverage in numerous forums. Major radio and T.V. stations also reported the fantastic findings.

I am so privileged to have been part of this incredible event and will continue to assist in any way I can.

John Ackerman