When I first met with Lisa about coming on this trip, one of the first questions I asked her was “Are education majors allowed to come?”. I was worried that I would not be able to go because I am not a geology major, yet I enjoy it just as much. She said of course education majors can come on the trip and that was music to my ears.
I am passionate about both education and geology, so this whole trip has been a wild ride of learning new subjects and trying to figure out how I could teach these ideas to my future students. As I have walked over many parts of the island, I have kept mental files of the information I am learning that could possibly be used later in my career as an Earth Science teacher.
Two days ago, our group had the opportunity to take a boat ride all over the caldera crater and it was incredible! One of our stops was on Nea Kameni, the newest volcano of the Santorini volcanic complex, and we hiked all the way to the top. Along our hike, Dr. Georges Vougoukalakis, a geologist who studies Santorini and who accompanied us on our or boat trip, would stop and talk about what we were looking at. He showed us some of the craters and pointed out the lava flows that we could see to our left and right (Fig. 1).
We talked briefly about the different kinds of lava that were present. When I looked around me, all I saw was dark gray and black jagged rocks that seemed to radiate heat off of them. But once I learned what they were, I had a new respect for the way the rocks were formed.
Under ground, magma is made out of melted rocks and minerals that have different chemical compositions. The big difference in the kinds of magma is the percentage of silica, a compound, dissolved in them. Rocks with a low silica content are called mafic, and ones with a high silica content are felsic. The mafic rocks are usually black, the felsic ones are white, and intermediate can range from gray to tan. Most of the lava found on Nea Kameni is intermediate and felsic.
Silica content also affects the viscosity which is a fluid’s resistance to flow. Felsic lava with high amounts of silica does not flow easily and resembles oatmeal or toothpaste. Low silica lava, mafic, flows easily like syrup (think volcanoes on Hawai’i). Since most of the lava on Nea Kameni is intermediate-felsic, it has a relatively high viscosity.
At one of our stops on our hike, Dr. Vougioukalakis talked about the rocks in front of us, pointing out weird shapes within them. He called them enclaves and explained to us how they were formed (Fig. 2).
Enclaves or xenoliths can get incorporated in two ways:
1) Xenoliths- rock that surrounds the magma chamber gets broken off and incorporated into the chamber. These rocks are already solid so they do not melt in the chamber when they are pulled from the wall (Fig. 3).
2) Enclave- This one is a little bit more complex, but let me explain… Think of a solitary magma chamber below the Earth’s crust that is about 800 degrees Celsius. That magma chamber is solitary for a while, but suddenly a new magma, a plume, comes up from from the depths of the Earth and is 950 degrees Celsius. Now these two sources are so close together that they start to mix the magma within them. But they do not mix well because they have different temperatures and compositions. The hotter magma enters the chamber and cools quickly because of the difference in temperature. Now there are pieces of rock from the second plume in the first one, and when the magma exits the chamber, it cools around the already solid rock (Fig. 3).
After talking about these types of rocks, Lisa and I talked about the Principal of Inclusions, which states that the rock which is incorporated, enclaves and xenoliths, are older than the rock that surrounds them. As I thought about this and applied it to the rocks in front of me, it made sense. The pre-existing rock must be older to be incorporated in the newer rock.
Walking around Nea Kameni with Dr. Vougioukalakis , we saw a lot of enclaves in the rocks. The lava that we saw came from a magma chamber just like the one in my descriptio. Enclaves that are found within lava flows are evidence that the magma chamber below Santorini is refilling. So cool!
Thinking like a teacher, I instantly thought of how fun The Principal of Inclusions would be to teach in a classroom. So for part of my blog post, I wanted to think of a lesson that I could teach to 11-13 year olds. I wanted to do it in a way that would be engaging and get them as excited as possible about Geology (I will be using a format that I learned about in one of my education classes).
-Before class: Arrange the students into groups and have igneous rocks prepared for the students to look at. Number the rocks so they are easy to reference later. Prepare the lab materials.
-Engagement: (How I will grab the students attention) Have the students observe the rocks in front of them. What do they look like? What words would you use to describe them?
-Exploration: (The students explore a topic without any core vocabulary or formal lesson so far) Have the students walk around the room to the other groups of rocks and observe. Ask the students to group the rocks that are similar to each other and write down why they are similar. Have one representative from each group write how they grouped the rocks on the board for the other students. Discuss the differences in the grouping and see if they can come to a consensus about defined groups. Do some of the rocks fit into more than one? Are you grouping them based on feel, color, size, density, or something else?
-Explanation: (Introduction of key vocabulary and core topics) Start with how magma is formed. Talk about the different kinds of lava and the effect silica has on it. Then move into The Principal of Inclusions, what an enclave and xenolith is, and the two different ways they can be formed. Show pictures of lava flows for visuals. Introduce viscosity related to silica content.
-Elaboration: (Build off of explanation) Mini lab on viscosity. Have two clear, rectangular tubs, paper towels, and a bucket each of oatmeal and syrup per group. Have them test both substances by tilting tubs and pouring in each one. Then discuss differences amongst each other.
-Evaluation: (Assess the students progress) Have the groups talk and come up with one thing they learned in the lesson. Be sure no groups choose the same answer.
As a future teacher, I am always on the lookout for future lessons to teach in my classroom. The other day, I was able to walk on Nea Kameni and see an active volcano. A world-renowned geologist named Dr. George Vougiokalakis gave us a quick tour and showed us the different lava flows, craters, and gases on the volcano’s surface. While on Nea Kameni, my mind was working on how I could teach The Principal of Inclusions and different lava types to students. One of the best ways to get the students excited would be to talk about the refilling magma chamber. What 12 year old wouldn’t be psyched to learn that another huge eruption is eventually going to happen on Santorini?