A student who was paying attention in their cave diving class can tell you that all caves were formed by water.
A student who was paying less attention might tell you that they were formed by giant worms or possibly dwarves mining for gold. You would be well-advised to learn to identify the difference between these two students.
Now a complete goddamn dork... one of those annoying gits who keeps asking questions in class even well after everyone else wanted to break for lunch...
They'd be able to tell you that the mechanism of formation that the water applies to the stone varies.
First is the chemically carving of the cave itself. Water from the surface percolates down bringing dead leaves and shit with it in the form of carbonic acid. That water aggregates and eats away at limestone as it flows its way back to the ocean.
Then the caves go dry which is when you get all the fancy dripstone and flowstone formations. All the fancy-looking tites and mites built out of the calcite left behind by evaporating carbonic acid dripping out of the ceiling on it's way to the sea.
Caves we dive in are wet, though; they don't stay dry. And right now, as they're wet, they're eroding away at all the limestone through which the freshwater is flowing. Erodes away at the calcite formations, too, though not as quickly.
Which leads to formations like this. These are my favorites. The ones that reflect the constant, ongoing cycle of droughts and floods.
Because this little fella was obviously a column. A column that sat atop a bunch of flowstone that covered a rock.
The rock underneath it is gone, though. The flowstone in the bottom of the picture is a huge umbrella shape that used to cover a rock that is no longer there. That base was dissolved away millennia ago when the cave was flooded and there was carbonic acid around to do the dissolving.
At some point in the dear, dim past, the stone shifted. And the column cracked. The base dropping by about 6in/15cm.
Then, at some point after that, a couple of little soda straws formed - during another ice-age/dry-spell, mind you - to re-connect the column it once was.
They never got the chance, of course, as the cave is flooded again. At least I hope it is, or I wasted an awful lot of time and money on dive gear getting this picture this afternoon.
So this little formation represents (at least) a five-change flood/dry cycle spanning over a "lifetime" measuring beyond not just every human civilisation, but our very species.
Perhaps one day the column will be reformed. Many thousands of years from now... thousands of years after the onset of the next ice age that drops global sea levels at least 50 feet or so, drying out this section of cave. And in the heart of that yet-to-be-reforged formation will be the memory of two soda straws that once had their picture taken.
Isn't that fucking spiffy?
"What do you see down there?"
"Just wet rocks, my friend. Just wet rocks."
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