by Teresa » Aug 28, 2006 8:55 pm
I'm pretty much against any destructive powered means in a cave. Even with a wire brush (which we used to good effect yesterday) the wielder can control the pressure, the direction, and has a second by second update on what he/she is doing, as opposed to grinders/sandblasters, where you have to let the dust settle some before you can see what you've done. It strikes me it's a whole lot easier to make an 'oops' with a power tool, than a brush at the end of your hand. Someone offered a battery powered grinder yesterday, and I declined.
Rock 'patina' is also known as a weathering rind. It happens more as a result of chemical exposure to substances (including oxygen) in the air, than to microbes, at least in non-sulfuric limestone caves. The difficulty with removing it is the rock below is often much softer, hence the concept that taking off the rind will cause the rock below weather--sure it will, but with a few exceptions (some sandstones come to mind), removing a thin layer of patina isn't that deletorious to the rock in a damp cave. It will reform fairly quickly. Dry caves are different, of course, and need more care. Now, the problem JDmentioned is that most petroglyphs, pictographs, etc, are strictly a surface phenomenon--remove the surface, and they're history.
What is 'historic'? Anything over 50 years old, so it is a moving target. You may notice that the FCRPA says something needs to be historic AND significant for it to come under its protection--the signature of A. Lincoln isn't preserved so much because it is historic per se, as it is signficant. Who decides what is significant?
Obviously a properly informed person, but it is there the question gets murky. Obviously, a scrawled signature of an 'unknown' becomes signficant if it is one of the discoverers, or an early owner, or a relative of yours, in addition to things which are considered generally of significance to the average layperson.
It's not generally a good idea to preserve everything. Neither is it a good idea to preserve nothing. The owner's wishes have to be considered--after all he/she in America has legal custody of the cave and its contents for his or her ownership.
Meanwhile we took grafitti off two heavily traveled by non-caver caves, on the theory that grafitti begets grafitti. Even so, for the traffic these two caves get, they are amazingly clean. By making them cleaner, we send the message cave walls are not billboards. By finishing them so they look 'natural' non-cavers may not even realize they've been cleaned.
Hey, you only do what you can do.