So, as I mentioned before, I drove last summer from British Columbia to Nova Scotia. It was a great cross-Canada trip, seeing provinces such as Prince Edward Island, Quebec, Manitoba, and Kentucky. For those geographic know-it-alls who told me “Kentucky isn’t a province, you idiot… in fact, it isn’t even adjacent to Canada”, the joke’s on you, as I don’t even know what ‘adjacent’ means!
I planned my route by seeing what UNESCO World Heritage sites were close by. It is a strategy with a few downsides, as I constantly realize that if I just drive a few hours to the south, I can get to one more World Heritage site. If Frank Lloyd Wright’s Fallingwater house hadn’t been declared one earlier in the summer, I might have kept going south through the Appalachian mountains into Great Smokey Mountains Park(designated a site in 1983), taking one small detour after another,and eventually find myself lost in the Everglades( inscribed in 1979).
As it was, Mammoth Caves National Park, in Kentucky, was the farthest south I went on that trip, before heading north to Pennsylvania. Yes, it is a World Heritage Site. They might try to hide this fact, but a clue on the plaque by the entrance gives it away.
Unfortunately, Mammoth Cave uses the definition of ‘Mammoth’ as meaning ‘big’, not ‘Mammoth’ as ‘ancient elephant monster’.
On the other hand, it’s really, really, big. There are about 650 km of interconnected cave passages. If it were one long passage running in a straight line, it would be long enough to cross into Canada. It isn’t, though; the caves are more like a snarl of branches and twigs.
So, I took two tours while there into the caves; I’m talking about the second one this time, because chronological order is boring. The second tour was called the Great Onyx tour, and took place in the Great Onyx cave…
…there is no onyx in the cave. As far as I can tell, there is no onyx anywhere in the park.
So, I was in Mammoth Cave National Park(no mammoths), going into Great Onyx cave(no Onyx). Anything else I can use to sue for false advertising? Oh yeah… Great Onyx cave isn’t part of the Mammoth Cave network. It doesn’t connect to the main cave(there are stories that one of the discoverers sealed it off in retaliation… it’s complicated). Basically, it’s lies within lies within lies. Sounds perfect!
The cave is also noticeable for setting a legal precedent in the USA that a landowner owns the caves underneath his land, even if there is no connection to the surface on the property. The legal writeup is here if you feel like wading through the jargon… I’m not going to, on the basis that I’m not smart enough.
Instead, lets look at pretty pictures!
The entrance to the CAVE OF LIES is a little underwhelming. A locked door seals the cave off outside official tours.
Inside the Cave
Inside the door are several steep, rocky steps leading down into the cave.
The colours are a little off because…Actually, hold up. I’d better put the pretty pictures on pause for a moment, and actually explain something. If you’re lucky, the following words will mean something, but no guarantees! Feel free to skip the next section. I won’t know.
And for all those who are reading through… lets do sciencing!!
Full Spectrum
As I’ve written before, I have a full spectrum camera, not an infrared or ultraviolet camera. I can use it as either, though, or as a regular camera. What ‘Full Spectrum’ means in this case is that the camera has no internal filter, so is able to record visible light, but also Infrared and some ultraviolet light. To narrow down what spectra the camera can view, I instead need an external filter.
I don’t use my full spectrum camera without an external filter very often; I’ve shown photos before of the ‘filterless‘ photos, but I’m usually much more likely to cut visible light out entirely and take an infrared photo or ultraviolet one. They’re much more interesting to me There is one scenario where I use a truly full spectrum photo, however. If it is extremely dark, going filterless lets me maximize the light coming into my camera.
How much this helps varies. As dusk, it can give me several extra minutes of being able to take quick photos without a flash. Most caves I’ve been in(including my other Mammoth Cave tour) use modern lighting, such as florescent or LCD lights.
You probably heard that these lights are much more efficient than older incandescent lights. The reason is that the newer lights only emit light in the visible range, not infrared or ultraviolet. There is much less energy expended.
Incandescent lights, on the other hand, also emit light in the infrared range(including a lot of heat, which can be picked up by a thermal Infrared camera). It expends a lot more energy to emit light that isn’t visible to the naked eye. It is visible to my full spectum camera, though.. at least some of it is.
The trade-off is that the extra light coming into the camera is something that the camera isn’t designed to record. Colours are off, usually looking more reddish than a normal camera’s photo would. In sunlight, it is easy to compensate for this by setting the white balance, although some objects(such as vegetation) are a different colour in the photo. At other times, there is so much infrared light that it drowns out the visible colours.
So, which kind of lighting does Great Onyx cave use? Great Onyx cave doesn’t use any fixed lighting. Instead, handheld gas lanterns are handed out. Flames are considered incandescent, so there is a lot of infrared light released… and I mean, a LOT of infrared light. How much light? I wanted to know myself.
I tested it out briefly in the cave, using the same ISO value and aperture on my camera(for non photographers- neither of these terms are important. I’m just trying to say I set the camera the same way both times). So I’m taking two photos with the same camera and lens, and the same settings other than shutter speed(which is what I’m measuring). The only difference is that one of the camera photos was taken with a BG40 filter. This filter pretty close to only visible light- it blocks a little red light and lets in UV light, but the camera isn’t very sensitive to the latter, and I doubt that the propane lanterns emit much UV light anyways. I’m not going to post my test photos here, as they aren’t that great… use these ones instead as a comparison. They’re much nicer:
I can’t pinpoint the exact amount of lighting difference between the two pictures, largely because the only light sources are in the hands of people moving around, blocking light, etc. The lighting varies slightly between photos, as it takes a few seconds to add or remove the filter. To my eye, though, it seemed the lighting was similar.
The results: Photos taken without any filter had a much shorter shutter speed than the visible light photos. The shutter speed was about 1/4 to 1/5 as long on average. As an example, the shutter had to be open for 1/6 of a second for one of the visible light photos, but 1/25 of a second for the full spectrum version. The color was off, but the detail seemed about the same. Basically there is about 4 times more infrared light recorded by the camera than there is visible light.
As I was on a tour, and constantly moving, setting up a tripod for visible spectrum photos wasn’t an option. As a result, I relied on a filterless camera very heavily for pictures; the photos were taken quickly enough I didn’t have to worry too much about keeping the camera still. I already have enough blurry photos because my hands shook, I don’t need to add to that collection.
I did try to adjust the resulting photos to simulate the visible light colours(note for photographers: Yes, of course I used RAW images(note for non-photographers: that is a meaningless buzzword I’m using to pretend that I’m professional)), but a some point, I realized that I was altering the photo more than I was comfortable with. Half of the reason I take these photos is to experiment in different spectra, so I don’t like to adjust them too heavily. I ended up with a compromise I was comfortable with; I still minimized the red tint, but tried to stick with just changing the white balance and contrast settings. They’ll still look red, but less red than the original.
Okay; I’m bored of science now. Too many numbers.
Back to the pictures.
Inside the cave
Hello everybody who skipped the last section. You missed a very well presented(if completely illogical and pointless) presentation on camera techniques and sciencing. I can’t really blame you. I don’t even remember it. I just remember a lot of math. I think I tried to cut it out of the actual writing, but there is a lot of it scribbled beside me. And I remember something…raw? I dunno.
I started showing all the photos without you. You missed this:
… and this:
This one too.
…and this.
Wait; why didn’t I fix this photo? In fact, why did I take three photos of the same columns? It might have something to do with science, because I’m getting math flashbacks. NO MORE MATH! OUT OF MY HEAD!
Okay. Where was I? I mentioned there were no mammoths… no onyx… CAVE OF LIES… descending stairs… Ah. here we are.
Mammoth Caves region has an interesting geology. Like many caves, it was created by water dissolving limestone. The limestone was deposited when the region was still part of an ancient seabed, about 330 million years ago(according to the scientists; however, I was unable to find a first-hand witness that would publicly verify this alleged sea). The soluble rock layers are divided into three section. However, it is all capped near the surface by a layer of sandstone. The sandstone is the reason that the caves still exist. It prevents water from entering and eroding the caves, as sandstone is not soluble in the same way limestone is.
As a side note, speaking as someone who has already used the word ‘sciencing’ twice in this post, I really admire the geologists who worked on this. Who else would ever name a formation of sandstone rock ‘Big Clifty‘? I mean I would… in fact, that would be my name for the Grand Canyon, but as I’ve already shown, I’m a bit of an idiot.
The most interesting formations in Big Onyx cave, at least on my tour, were close to the entrance. The sandstone layer is not as prevalent near the entrance, allowing the water to dissolve the limestone more quickly.
Some water does leak through the rock, carrying dissolved minerals. When it dries up, it leaves the minerals behind. In some cases this forms weird formations of gypsum crystals and strange formations on the cave walls.
Of course, the stalactites, stalagmites, and columns are formed through a similar process.
Deeper in the cave, where the sandstone layer is stronger, there are less formations. The cave becomes drier and less water percolates through. Of course, there is always the possibility that tourists took away and formations that did exist… If it has been open to the public for a century, unfortunately there is the possibility of vandalism.
I was going to post some 3D photos of Onyx cave here, but this blog entry is already approaching 2000 words, and I’m worried that if I keep writing someone might assume that I actually know something. So, I’ll do those next time.
Until then, I’m not going to joke anymore about ‘Big Clifty’, as it was mentioned that I live beside the ‘Rocky Mountains’.
Geologists are a tough crowd to please.
The above photos were taken with a modified Canon T3i camera or as Canon SX600 HS camera.
Parallel Views 