By Rodney D. Horrocks (NSS# 25107)
After obtaining a paleontology permit, Jim Nicholls, Ken Stahley and I took a reconnaissance and collecting trip on July 4, 1987, to Nielson's Well. On an earlier trip, while surveying in the Big Room, Ken and Jim had discovered a lead that was blowing air. They didn't enter it due to time constraints, but it was duly noted in their survey. During a later trip to the cave Mike Beer and Ken entered the lead and discovered that the lead contained several skulls of small mammals. The lead is located where a breakdown pile intersects the cave wall. The lead has since come to be known as the Bone Lead. Realizing the importance of the find, Ken and Jim contacted the only paleontologist-caver they knew that had vertical experience. I was more than glad to help them out, and not long after, found myself at the bottom of a shaft more than 300 feet deep inspecting the find.
From the start I realized that the find would represent a puzzle. Located on the west side of the Big Room, the Bone Lead is at the top of a steep and unstable pile of breakdown about 30 feet high. At the entrance to the lead, is a pile of dirt that appears to have originated somewhere inside the lead. It has the distinction of being the only dirt found thus far in the entire cave. Inside the lead the same soil deposit is found throughout the maze of incompletely explored small crawls. The deposit continues until the second pit, Twin Domes, is encountered. The paleontological remains are found in the dirt crawls and at the bottom of the 70 foot deep Twin Domes.
Mixed in with the breakdown in the Big Room are numerous decaying logs. Jim had reported to me that he had seen what appeared to be charred logs on ledges 40 feet above the floor of the Big Room. He postulated that the room might once have filled with water, floating logs onto the ledges. Unlike most large breakdown rooms, this room has breakdown around its edges and a debris filled bowl in the center. These facts must be considered when attempting to come up with an origin for the bones in the Bone Lead.
Upon inspecting the deposits, I noticed that many of the skulls had post-cranial material associated with them. In the Bone Lead, the post cranial bones tended to be slightly disturbed and scattered, however, not to the point of making correlation with the skulls difficult. At the bottom of Twin Wells, I found the entire skeleton of a porcupine laid out in exactly the position it probably had died in. I also found a couple more rather well articulated porcupine skeletons.
Most of the skeletons turned out to be-porcupine. However, one partial badger skeleton was found. One of the most unusual finds was a complete wolverine skull with no associated bones. The wolverine skull was found slightly buried in the sediment, with full lower jaws and all the teeth still intact, certainly an enigma! In relatively recent times, the wolverine has become extinct in Utah, a fact that adds interest to its discovery in Nielson's Well.
My first guess was that wood rats were responsible for the bones being taken into the cave. This could also explain the dirt. However, I found none of the customary gnaw marks on the bones to substantiate this theory. More importantly, the skeletons wouldn't have been articulated if brought in by rats.
My next theory was that a connection, such as a sinkhole to the surface, had somehow introduced the bones into the cave. After searching, I was able to find some small chimneys in the ceiling of the Bone Lead, thus adding credence to this theory. However, no significant chimneys were found in the two trips taken to explore the Bone Lead Maze.
My next theory looked at water as the medium of transportation for the carcasses. However, saying that the animals must have fallen into a water filled room and then floated up and into a very small and insignificant side passage, seems unlikely. Although I did not see any paleontological remains in other parts of the cave, with a more thorough search we would undoubtedly come up with some. So there might be something with this theory.
My next theory took the form of a now blocked horizontal connection with the surface that leads into the dirt crawls of the Bone Lead. This would have allowed animals to enter the cave under their own power. Such an entrance would have to have been on the side of the mountain some distance away (since the current entrance shaft is now on top of the mountain). This is still a possibility, because the Bone Lead maze area might have some digs that could lead to more cave. At this point, it is obvious to me, that in order to narrow the field of theories down to just one, more field work must be completed.
After carefully mapping and photographing the find, I collected the skulls and associated bones and placed them in Zip-Lock baggies with an identification number that correlated with my map. The baggies were then packed into a 5 gallon plastic bucket filled with styrofoam peanuts. By tieing a sling around the bucket, and the bucket to a Jumar, I was able to ascend out of the entrance pit with the bucket hanging below me (Ed. Note: Unfortunately, the end of the rope got caught on the bucket and I pulled the rope up with me as I ascended. By the time I reached the top I was carrying, unknown to me, the entire rope up the pit. I remember wondering why the bucket seemed to get heavier and heavier as I climbed! By the time I neared the lip of the sinkhole, I was using nearly all my energy just to move up a few inches at a time).
Once back at the BYU Earth Science Museum, with mammal skulls and post-cranial bones in hand, I cleaned, numbered, and then cataloged each bone into the Cave Vertebrate Collection. Identification down to genus was accomplished at that time. However, what has been done thus far is strictly a preliminary study (Ed. Note: By contacting the curator of the BYU Earth Science Museum, the bones can be viewed).