an underground tour in Mercer Caverns

It was a cold and rainy winter day but the gloomy weather did not dampen our spirits. Ate Maddie, JP, Mommy, Daddy, and I trooped to Mercer Caverns deep within the Calaveras marble formation. This trip brought back memories of Professor Dimaandal's general science class back in high school. In that class, I learned that marble is a type of metamorphic rock; that is, a rock type formed by chemical changes in the parent rock caused by immense pressure and heat deep within the Earth. I assume that the rocks here are sedimentary rocks because there are no volcanoes (that I know of) in the area... otherwise, I'd say igneous rocks were the parent rocks.

... which brought me to a concern of mine: What should we do in case of an earthquake? We're hundreds of metres underground. Could we get out in case the earth shakes? 

Our caving guide told us that being in the cave was probably safer than being on the surface when an earthquake hits. According to him, most quakes happen in shallow depths; we were going 160 feet down, beyond the reaches of earthquakes. Again, I tried to search my brain for Prof. Dimaandal's geology lesson. The earth shakes in waves, with those occurring on the surface being felt the most and causing the most damage. Unless a fault-line runs within Mercer Caverns and/or the earthquake is a really large one, cavers would relatively be safe. Can they get out is a totally different question, though.  

As we went deeper into the cave, I put the earthquake issue at the back of my mind and started observing the formations. We were not allowed to touch them because our hands have fatty acids that may react with the rock formations. It's alright... after all, this is the first time that I've seen stalagmites and stalactites in real-life. The strategically placed lamps provided stunning lighting on the formations. I felt I was going under the sea, without water.

Under the water indeed. Because we also saw coral-like crystalline formations. These formations are called aragonite. No, not named after the King of Gondor and of Arnor, unfortunately; rather, these mineral formations were named after Aragon, the Spanish autonomous community. If I only saw photos and not the real thing, I'd think that fish were lurking beyond these formations. Plus, they're all so pretty!

Reading up on these aragonite formations, I learned that aragonite is made of calcium carbonate. It's quite different from limestone, which I've encountered back in Prof. Dimaandal's general science class. What I like most interesting is the crystalline structure of aragonite. Too bad we're not supposed to touch them.

After our trip down the cavern, which in no way was similar to Alice's fall down the rabbit hole, it was time to go back up... and I dreaded this part because I could see nothing but ascents. Yes, there were steps but they were steep! 

Surprisingly, the climb didn't turn out to be that difficult. There were a lot of stops by the tour guide to point out interesting features on our climb up... suffice it to say we had a lot of rests.

During this whole tour, for instance, we took the illumination for granted. We wondered about the beauty of the cave formations but they were visible only because of the lamps installed. Our tour guide then showed us how a cavern tour used to be like.

It was pitch dark. 

How were tourists expected to traverse the cave in the dark? Why, with a wooden board containing candles, of course! The tourist held the board with his mouth so that both hands were free for rappelling. That's right: rappel with a board between one's teeth, loaded with candles.

I bet the cave wasn't even lit up that brightly so the tourists didn't see as much as we did.

That's such a fun trip to Mercer Caverns, made possible by Ate Maddie and JP who invited us to go with them on an adventure weekend.