My husband and I were at Meramec Caverns recently and during the tour we were told that touching a stalactite or stalacmite would “kill” the entire formation eventually because of the oil on our hands. Is that accurate? If so, is there some minimum surface area that must be touched to kill it? And what processes occur to kill the formation? And what does killing it mean - that it stops forming, dries out, or a combination of things? Thanks in advance!
Don’t go around touching stuff in caves if you don’t have to, OK? You’ll ruin stuff that other people want to see.
Having said that… I don’t think finger oil == instant stalactite death. I think cavers have to over-warn people on this, because if everybody goes around gripping stalactites, there’s a danger of significant oil/mud buildup, plus according some cites I’m reading it’s possible for oil to disrupt mineral buildup in a way that a hand-shaped discoloration can remain there permanently (like wire fence wrapped around a growing tree… it’ll keep growing but it will go all misshapen).
Oil is an organic molecule, at some point it’s going to break down and nature will continue to take its course. Plus, in a cave people generally won’t be walking around touching things with oily hands, it will be more like muddy gloves (which might be even worse with all those thick layers of mud).
Of course, even if you do stain one, in a thousand years, people will be all “What fascinating ancients must have lived here!” or “Behold the mysterious wonder of nature, Handprint Rock!”. When we talk about damaging nature, we’re mostly talking about damaging things we can enjoy in our lifetime, which IMO is just as important as anything else. So again, don’t go touching the pretty rocks, OK? I haven’t seen them all yet.
Thanks for the response! And for the record, we didn’t touch anything - just because we questioned whether cave touching equals instant death for the cave, we’d prefer not to risk it.
What does “instant death” mean in reference to a cave formation? Clearly, stalactites are not “alive”?
If you put the word in quotes, they can be. When water is dripping from them, minerals dissolved in it are deposited and the stalactite slowly “grows” (i.e. increases in size).
Here’s a bit on the effects even well behaved visitors can have on a popular cave:
If a cave has enough visitors, none of them even need to touch anything to mess things up .
What Cosmic said. Also, cave formations involve crystal growth, which can be knocked awry by VERY small amounts of contaminants or microscratches. Easy to donate both on surfaces that are soft and absorbent, like active stalactites.
I recall seeing a show about some spectacular cave somewhere.* Part of the exploration had to be done by swimming. Rather than taint the crystal clear waters by traversing it clothed, explorers were required to pack up their clothes and swim nude. Wouldn’t a wetsuit have been a better solution?
*Yeah, I know, not all that helpful.
Oils and mud deposited by contact, plus the lights, can lead to algal growth, too. These damage the surfaces and can distort the growth of the feature. I’ve seen some calcite whiskers that would dissolve if moisture from your hand got on them - we could only pop in to look for a few seconds, because the water vapour we emitted disturbed the conditions, plus the air movements could break them. I only got to see them because three of us stayed back when one of a larger party could not make it through the “organ grinder” (yep, that organ ;), and it wasn’t me), and we had some time to kill and a great guide.
Cave tourism is a delicate balance between letting people see marvelous things, and protecting those very things from people who want to see them.
Si
More like an excuse to get nekid. 
Logically, the same fibers that detach from the outside of clothing would detach on the inside and thus be washed off during the swim just as other bio-material. A wetsuit would be better IMO.
When you think about it, cave tourism is more likely to freeze or slow the process down, thus preserving what is there. What difference does it make if it continues “growing”. It would eventually fill itself in. It’s not like it automatically becomes better over time. If you let Niagra falls erode backwards for 10 miles you end up with a rapids.
I’m not one to go overboard with warnings of total doom and destruction, so I’m less likely to say touching something will kill it or destroy its beauty forever.
That being said, I was a cave guide for a couple of years, and I did point out a low spot where someone brushed their fingers along the ceiling. The marks in the damp ceiling were clearly visible in the condensated water droplet pattern for a long time. I’m pretty sure they were there for at least a year, and probably the entire two years I was guiding. It’s been 15 yrs now…I’d like to go check out the marks, but the cave is closed and protected now.
There’s more than just pretty formations too. I was lucky enough to go on a tour of a research cave inw hich they’ve discovered all sorts of microbes, munching away on the cave’s interior. These microbes have serious viability in medical research, but are extremely delicate. So delicate, they had to set up a portable lab in the cave, because the microbes were so sensitive to changes in temperature and light, that they had too much trouble trying to get the samples out to study them in a lab without killing them.
There were entire sections roped off where no one was supposed to touch anything. Sure the oils of your hands affect the stone (we had to wear long shirts and gloves at all times when in the cave), but there are also other repercussions to touching stuff in caves.
Nearly thirty years ago, I got to go on a 4th grade Girl Scout trip to Natural Bridge Caverns, just north of San Antonio.
Just inside the entrance of the cave is a stalagmite stump that the guides encourage everyone to touch as they pass by. In a twinkling cave filled with alabaster colors, the stump was covered in black smut, giving plenty of evidence just how damaging accumulated human touch could be.
I imagine that while one person touching a formation isn’t great, it’s never one person. You look at a stalactite and think “oooh, pretty!” and reach out to touch it. Well, so do the next five thousand people who troop through the cave.