After a brutal mile hike and an elevation gain of 369 meters, I reached Ancient Thera, one of the many reasons I wanted to visit Santorini for school. Located on the Southeast corner of Thera, the Spartan town of Ancient Thera was once used as a port for war purposes around the 9th Century BC. As I walked into the ancient city, I could see the civilization, like many others, in ruins with crumbling walls and roofless structures(Fig. 1)(Fig. 2) . For many, the ruins look like scattered bricks layered on top each other with little importance, but to an anthropology major, the ruins remind me of the past, of what could have been. They demonstrate the greatness of the Spartan military and their empire. Since I came for geology though, I also look for the story and history of the rocks and how they landed at the second highest point on the island.
At first glance, the ruins look like many other Spartan ruins, but what made Ancient Thera special to me were the large blocks of black andesite and red scoria built into the walls compared to the white limestone, which most of the city is made of . Only the ruins of ancient Thera had these massive stones embedded in their walls which brings us to the question: Why? How did these blocks get here and why were they so important to the Spartans?
Andesite (Fig. 3 ) is a type of volcanic rock and which can be found almost anywhere on the island making it easy for the Spartans to obtain the rocks and use them to build their city. Andesite is formed from lava flows which contain an intermediate amount of silica (SiO2) content of 53 to 60 percent and erupts around 800 to 1000 degrees. These two aspects combined create a medium resistance to flow, or viscosity (think honey). This type of lava would have built up over time as Santorini passed in and out of its dormant and active periods. During the Minoan eruption, the vent would have exploded from the power of the eruption leaving andesitic blocks sproaditcally across the island. The Spartans would have then utilized them to build their structures .
The other ‘rock that doesn’t belong’ in the walls of Ancient Thera is red scoria. Cinder cones are volcanoes that have one explosive event and create this red scoria. The magma breaks because high amounts of gas in it expand so quickly that the magma cannot withstand the pressure and then fragments into scoria pieces . The high amount of gas causes scoria to have many vesicles (holes), thus red scoria is very bubbly. It originates from mafic magma which has a SiO2 content of 45 to 53 percent and erupts from 1000 to 1200 degrees celsius at any time. Both silica and temperature create a low viscosity for mafic magma (a low resistance to flow…think oil). Scoria is naturally black because it’s basalt but through oxidation (iron reacting with the air) it turns into a reddish orange color (Fig. 4).
On Santorini, the red scoria dates back to roughly 650 to 550 thousand years ago and though the exact location is unknown, the scoria would have come from early Akrotiri on the southwestern tip of Thera (Fig.5). For the Spartans to build a city with blocks of scoria, they would have needed to travel a minimum of four miles just to collect the rocks and then another four miles to haul them back to Ancient Thera (Fig. 5). The determination of the Spartans was incredible because not only is the trek long but it is also steep, let me remind you that the hike to Ancient Thera is almost 400 meters straight up. Most Americans don’t even have the motivation to cook their own dinner but would rather just get take out at McDonalds. Just imagining the strength and will power it took to build such an amazing city is exhausting to think about but it does illustrate how advanced the Spartans were when they were in their prime.
Ancient Thera maintains a special appeal because of the volcanic rock that is embedded in the walls of the houses, baths, and city structures. Collected from all over the island, the rocks utilized bring a sense of uniqueness and also create a story behind the construction of their homes. For me, when I see the structures I read a story of how the city was built, what the Spartan society was like and how they went along with their daily lives. Though the exact reason as to why they collected red scoria and black andesite is unknown, it brought a certain pop that is not found at many locations. Regardless of if you study anthropology or geology, Ancient Thera is worth the an hour of burning calves. `
”Santorini Archaeological Sites : Ancient Thira.” Archaeology / Ancient Thira. SANTORINI WEB PORTALS, 2015. Web. 4 June 2015. <https://www.santorini.com/archaeology/ ancient_thira.htm>.
Friedrich, Walter L. Santorini . Denmark : Aarhus University Press, 2009. Print.