Karavolades Stairs: A 600-Step Geologic Wonderland

May 30th, 2016 15:00: A group consisting of 11 geology students, a T.A., and a professor, finally roll into the caldera of Santorini after an eight-hour ferry ride (let me mention, this ‘ferry’ was definitely the size of a small cruise ship). All passengers swarm to the left side of the ferry to get the best view of the place of their home, honeymoon, or in our case, our classroom. After it took me too long to find my glasses, I was immediately speechless by what I saw.

I heard people, with all of their various accents, talk about the beauty of the white houses and how nice they all looked on the cliffside. Yeah, I saw the houses, but my eyes shot down. I was looking at the rocks that allowed these houses to sit where they are.

Rocks in shades of red and brown are stacked on top of each other as if someone was layering sheets of cake. Thick rounded puffs of black rock protrude from the edges of the rim. A hefty layer of white rock blankets the outermost part of the island. “There are no words for what I’m seeing”, I thought, “How could I describe this to anyone?”

I felt two emotions at that moment: frustration and excitement. Why frustration? I knew at that moment, I would not be able to share this experience of mine with anyone. There was no way to capture the exquisite beauty of Santorini – not through any assortment of words pictures.  Why was I excited? For the same reason. This experience would be unique to me. The memories and knowledge I will gain will be mine to cherish. From that first glance, Santorini began to speak to me, and I began to listen.

May 31th, 2016 11:00: This day, we walked down the path known as Karavolades – a 600 stair pathway from Fira down to the old port. I had remembered seeing this switch-backed walkway from the ferry the day before (and I was crossing my fingers hoping that I would not have to walk up it…little did I know…).

This walk was one for the books in many aspects. First off, the smell of fresh donkey feces is not to be forgotten. Second, and more relevant, was the view of the caldera cliff that we got in our journey down. Being in the ferry, I was able to see the caldera as a whole, kind of like a puzzle piece perfectly put together. Now, on this walk, that I was up close and personal with each specific layer and I was starting to see each bed of rock as a puzzle of its own.

Geologically speaking, they way in which I was viewing the rock from the ferry would be referred to as macro scale, meaning that I was taking a step back and seeing the caldera wall as a whole – noticing the colors, layers of deposition, fault lines, marker beds, etc. When I was making observations from the walk itself, I was looking from a meso scale, meaning that I could look at each individual layer and identify similarities and/or differences specific to that bedding i.e. size of grains, sorting of grains, presence of other rocks, etc.

From the macro scale I was using on the ferry, I was unable to see bedding within the layers of rock, simply because of the distance separating me. On the walk down to the old port, after I got past the smell of donkey feces, I was able to use a meso scale and actually see the rocks that compose these beautifully constructed layers.

All of the layers encompass their own beauty and uniqueness, but there was one section of rock that caught my attention immediately. From the top, on about the 8th switchback, as I was trying to catch my breath (exercise really isn’t my thing), I noticed something peculiar about a layer of rock. Imagine a tiger, except instead of mostly orange with black stripes, it is mostly black with orange stripes. Now take that image in your head and attach it to a rock. Incredible, huh?

My professor, Lisa Skinner, provided me with the photo seen on Figure A. This figure outlines the layer of rock that I had seen on the walk, except this is a view from the ferry. From this macro view, this rock layer blends in pretty well, as the orange stripes cannot be seen from this distance.

image
Figure A: This figure shows the edge of the caldera rim from the ferry, a macro scale. The walkway is in yellow and the outcrops of the black and orange band are outlined in red (Photo by Lisa Skinner).

Ever since I was a kid, I was always the person to ask too many questions, so naturally, I bombarded Professor Skinner with a bunch of questions regarding this unique layer. “What is this layer? And why are there orange stripes here but nowhere else?”, were just a few questions that my very curious self asked.

Figure B, below, is a photograph I took on switchback 8 coming from the top of the walk. Here, you can see the black and orange band in relation to the surrounding layers and the orange stripes start to be clear to the naked eye.

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Figure B: From this meso scale, one can start to see the orange stripes with a naked eye. The yellow is outlining the pathway and the red is showing the location of the outcrop of the black and orange tuff (Photo by Jenna Chaffeur).

The reason this layer stands out from the rest is because this layer formed from pumice fall that was SO HOT (around 535°C [2]) upon deposition, that it ‘welded’ together to form a solid rock. This welded layer is called a welded tuff (tuff meaning layer of ash and pumice). The orange layers within the bed reflect a change in deposition of the pumice.

These orange zones are pumice pieces that did not get as hot as the surrounding black rock, and thus, did not weld. Rather, these beds of pumice expanded and became deposited in the welded bed as pumice fall. The reason they look orange is because the rock oxidized- a chemical weathering process where iron essentially rusts [1].

The high temperatures required to weld the tuff also made the material plastic-like and malleable. This weakness in the rock allowed for bigger chunks of pumice to collapse under pressure and continue the welding process [3].

Figure C, shown below, is a photo taken from the book, Santorini – Volcano, Natural History, Mythology. In this photo, the uniqueness of the black and orange layers are clear.

image
Figure C: This photo shows, in scale to the hammer on the bottom, the black and orange layers of rock in relation to one another [1].

Learning about the welded tuff gave me an insight into the power that this volcano has held in the past and sustains to this day. Not only did the volcano erupt meters of ash and pumice, but it did so so violently with such high temperatures, that a new rock layer was created almost instantaneously. That is impressive…and scary. 600 steps up the side of a caldera cliff sounds intimidating, and like the work out of a lifetime, but I absolutely recommend doing so. Santorini has a story to tell, and going on this walk was just the introduction.

[1] Friedrich W.L., 2009, Santorini – Volcano, Natural History, Mythology: Denmark, Narayana Press, 312
[2] The University of Auckland, 2005, Geology Rocks & Minerals: https://flexiblelearning.auckland.ac.nz/rocks_minerals/rocks/ignimbrite.html (accessed June 2016).
[3] San Diego State University, n.d., How Volcanoes Work: Pumice-Flow Deposits: http://www.geology.sdsu.edu/how_volcanoes_work/Thumblinks/ignimbrite_page.html (assessed June 2016).

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10 thoughts on “Karavolades Stairs: A 600-Step Geologic Wonderland”

  1. Great job Jenna – I wasn’t sure how you were going to pull off only talking about this one layer but I think it works. The changes you made really solidify the story and I am learning a lot about your personality through your writing.

    please add physical volcanology as a category. 🙂

  2. Hi Jenna,

    This is such an interesting topic because it seems to be fairly unique to Santorini. Just by reading your post I can tell that this is certainly a complex topic, and I think you did a great job at making this information accessible to an outside audience. One particularly effective way you did this was by immediately following scientific jargon with a brief summary statement as an explanation (this was definitely helpful during your discussion of macro versus meso). This style of writing works well to establish your credibility as an authority of the topic without excluding an outside audience.

    I agree with Dr. Skinner that your personal voice is present within your narrative throughout your post, and this definitely intrigues readers because we can get a glimpse into what you’re thinking and feeling. I like that you used your outlook of the rocks from the initial experience on the ferry as a contrast for what you saw and experienced up close during your long trek. This type of narration helped me as your reader experience what you did: going from macro to meso. This contrast between perspectives is an excellent way to hook the reader, and it was fun for me to follow along with.

    One thing I would have liked to see earlier on was some pictures! I read your wonderful description of your view from the ferry and expected to see an image associated with this description. However, I was glad to see that your images did show the difference between viewing the rocks from a macro and meso scale. Those images really helped me visualize your discussion points while I was reading.

    Overall, this is an excellent post because the narration is intriguing, your images support your ideas, and you explained complex geological information in an approachable way. Keep up the great work!

    Marisa

    1. Marisa,
      Thank you so much for taking the time to read my blog post! I really appreciate your feedback and I’ll try to incorporate more photos early on in my next post! Thanks again for the helpful comment.
      Jenna

  3. Jennnnaaaaaa,

    You said “‘There are no words for what I’m seeing’, I thought, ‘How could I describe this to anyone?'”, but your attempt was darn good. I may have the advantage of having seen it before, but your language was very visual and I’m sure your other readers’ imagination was close to the real thing due to your words.
    There are so many geologic concepts in this post, I’m not sure your readers even realized how much they learned from your post. You weaved scientific content with your voice flawlessly (feces? Ew).
    From your description of the black and orange rock, both colors are composed of pumice and ash. You said the orange rock is that color because of oxidation, but why is the welded pumice and ash black? Is that a due to weathering or a byproduct of the welding process?

    Well done.

    Alex

    1. Hi Alex,

      Thank you so much for your feedback. It was a challenge to try to incorporate the geologic aspects that I wanted to address while also conveying my personal experience, so I really appreciate your comment.
      In regards to the question you asked about the black color of the pumice and ash – First of all, thank you for that question! That was not a topic that I had thought about in my blog research that I wish I had. Second, I actually do not know the answer to it and now I am very curious!
      Thank you again for your constructive feedback!
      Jenna

  4. Jenna, really enjoyed reading your post. Very informative and well-written. I could close my eyes and imagine I was there. Looking forward to reading future posts!

    Love you, Dad

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