Saturday, November 10, 2012

Cave Photography, Part 2

As promised in my last post, here are the pictures from the second part of my latest spelunking trip. I'd have had it up earlier but for working quite a bit over the last week and not feeling up to the task of writing this post, which will probably take me at least an hour.

Anyway, after exiting from the mauka side (uphill, left in this case) of the cave, we proceeded into the makai side (downhill, right in this instance). This side of the tube has a much larger entrance that allows light to shine much further into it.

View from just inside the entrance, with the steps from last post in the background.
I was so enthralled with the view back out the entrance, that it took me a few minutes to turn around and actually look inside the cave. When I did, imagine my surprise and delight to find an amazing example of a tube-in-tube formation not more than fifty feet into the cave!

A tube-in-tube is a structure that forms inside lava tubes for reasons that have to do with why lava tubes form in the first place. As the lava level in the tube drops, it begins to cool and can eventually form a hard crust on its surface within the original tube. Sometimes this crust can break in places when the volume of lava coming through the tube picks up again, and you get this neat effect where the rim of the break is coated in a layer of smooth, liquid-looking rock where the lava surged out of the hole, then flowed back in.

Anyway, one of these formations lies just within the makai opening.

Tube-in-tube formation just inside the cave, looking back.
In the picture you can see the extremely smooth rock around the edges where the lava surged up and down, and also the rougher rock forming the crust over the channel in the middle.

View of the cave entrance from just beyond the tube-in-tube formation.
Counter-intuitively, the tube-in-tube formation doesn't exactly cover the entire floor of the lava tube. Instead, it has these sort of ridges (officially called “­levees”) that stand up vertically out from the walls of the tube roughly parallel to them and act as the sides of the channel. Already at this point they're much more pronounced than they ever are in the mauka side of the tube, but further on they're even more impressive. You can kind of see the gap between the levee and the wall in the bottom-left corner of the picture.

Same view without flash to better capture the feel of the cave.
This picture does a better job of capturing the view, although the walls and ceiling are still a bit brighter than they appear to the eye.

Another view of the entrance from further in. Note the hanging roots and sulfur on the walls.
One thing that struck me about the makai side is that light from the entrance is visible much further in than it is on the mauka side. This picture is probably between a hundred and two hundred feet in, and the opening is still visible. Compare to the mauka side, where the nature of the entrance is such that by fifty feet in it's pretty much pitch black.

I believe this is a mild case of what are called “shark-tooth stalactites”.
Another thing I'm learning from all this cave photography is the importance of shadow for establishing depth, and the need to keep in mind that in a cave, you make your own shadows. It's an interesting learning experience.

Example of a levee.
Remember those levees I mentioned earlier in the post? Here's a shot showing a nice example of one.You can see how it sits about a foot from the wall, and closely parallels it, even around curves. Here the crust on top of the tube-in-tube formation wasn't strong enough to avoid collapse when the lava flowing through it dried up, leaving only the stronger sides as levees.

More of the levee on the floor, and a ledge above it about waist high.
Further on down the cave, the ledges on either side of the tube come together, and you have to climb up about waist height onto a thick ledge to continue. The lava flows in the area make some really strange looking shapes.

Hardly looks like solid rock, does it?
This part of the cave is very interesting, as the tube is split roughly in half by a ledge of reddish congealed lava of varying thickness. Holes appear in it periodically where lava surged up through the cooling crust and flowed back down. In the area beneath are some really nice examples of pāhoehoe lava:

Pāhoehoe lava in the lower half of the lava tube.

Here you can see one of the holes where ledge was especially thick.

Finally, at the point we reached before having to turn back due to prior engagements the ledge again split into two ledges on the sides of the tube before disappearing entirely as the whole tube abruptly shrank in size, in a manner very reminiscent of a river coming together before entering a narrow canyon to form rapids.

Here the ledge splits apart again before the tube narrows. This rock may have been placed by lava.
All in all, it was a fascinating journey, and I would love to go back and go all the way through. Since the next part of the cave appears to be some sort of “lava rapids”, I expect it should be pretty cool. Next time though I need to remember to bring gloves for crawling around, as the makai side seems to have a lot more low-hanging areas best suited to crawling than the mauka side. A hui hou!

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