Here is the presentation that summarizes how what we saw relates to the processes we discussed prior to and on the field trip. Also a document that includes all the comments that I received from the trip participants – good observations and thoughts and some insightful recurrent themes.
I hope that you have all recovered from the trip back. Thank you all for being a great group on this trip, all my colleagues, the tour guide and even the hotels commented favorably on the behavior and level of interest of everyone in the group.
1. I have reconciled the expenses from the trip and we are pretty much on budget. Each student owes me $363.26. Please transfer this to me using Paypal (firstname.lastname@example.org), cash or a check. Since you had a ~$210 difference in your student account between the scholarship and the field trip charge, this makes the remaining cost to you ~$153. (Brandon, Ben, Gillean, and Miles see me separately).
2. We will have a summary meeting next week on Monday or Friday afternoon of the week of April 16-17. Let me know which times you can make at: https://doodle.com/poll/mcf6648rrq63cvrp
3. Brandon will let you know where to put your best photos from the trip at the start of next week. I have been sorting though mine! Here are two of the group photos and a third of the group at the base of the fault surface.
No more rocks? We hear your wish! Located in the center of Heraklion, Crete, the Heraklion Archaeological Museum is one of the most important museum in the world with tons of collections of Minoan civilization.
Heraklion Archaeological Museum. The door is the key to the past, though it takes a while to open.
The earliest tools under the Minoan palace site. Stone axes and bone awls 4500-3000 BC.
Luxury Minoan life. Delicate jewelry and rock crystal were made 2600-1900 BC.
The Phaistos disc. The earliest European language that has not been deciphered yet. The unique scripts were gradually replaced by Linear A.
The Snake Goddess showing their ritual in Minoan age. The snakes may represent death and rebirth. 1650-1550 BC.
Bull-Leaping Fresco. Perhaps one of the most impressive Minoan activities. The painting represents a kind of sport, ritual or just purely decorative.
Then we drove to see some rocky things: “Europe’s oldest city” – Palace of Knossos. This palace was built as the civil central of Minoan civilization starting from Neolithic period to Bronze Age (~1700 BC). Beautiful!
Modern people are looking at Greece ancient building architecture reconstructed by old English researchers…
The whole view of the palace from “the oldest theater in the world.”
After cool archaeological sites, we drove back to the beach of Amnisos Bay. Intriguing tsunami deposits associated with Minoan civilization. Such tsunami deposits may have been induced by Santorini eruption. (p.s. The relative sea level was 3 meters lower then present)
The remnant wall of a “Villa” was cover by chaotic sandy layers, which contain broken bones, potteries, poor sorted angular pebbles with diverse composition (including some pumice).
In the end of day, we moved back to the Natural History Museum, had a brief summary of this field trip, and ate delicious food together!! Thanks for comprehensive talks by Emilie and Ben.
Cool bathymetry map around the Santorini islands. Lots of extensional basins and maybe some big left-lateral strike slip fault!
Good dinner with traditional Greek food and wine. Thanks for the organization from both UO and Greek professors leading such a smooth and fascinating field trip!
-Larry and Tim
On our second day in Crete, we drove into the mountains around Psiloritis.
The Cretan detachment fault exposed under a highway bridge. Shear zones from an old thrust fault, shearing toward the north. The contact was reactivated in the late Miocene as a normal fault shearing toward the south. 2 euro coin for scale.
Almyros spring, the largest spring in Crete, is a brackish karstic spring. Water from the Tripolitsa unit and the Psiloritis Mountains travels the 25 km to the spring in just 9 hours. Another system brings sea water into the cave system, hence the brackish composition. Water flow in spring, when the water is fresh, is enough to supply ¼ of the island’s demand, but there’s nowhere to store it year-round.
Voulismeno Aloni Pothole. A karstic depression in Tripolitsa limestone. This was a cave once, but the roof collapsed leaving an impressive circular hole. This feature is connected to the Almyros spring.
Massive marble below, part of the Plattenkalk Unit, upper Triassic to lower Jurassic in age. Plated marble above, upper Jurassic to Oligocene in age.
Impressive folds at Vossakos, in platy marbles of the Plattenkalk unit. Axial plane dips to the north. Folding is from the Oligocene due to early subduction processes. The thin white layers are silica.
Boudinage in Vossakos. This indicates the sense of deformation.
We stopped for lunch at the Psiloritis geo-park in Anogeia. There are no traditional buildings left in the town, because the Germans destroyed it during World War II.
On the way to our next stop at Nida Plateau, these goats didn’t wait for our bus. This was a common occurrence in the mountains. In the background is Psiloritis.
The view from Nida Plateau. The shadowy line just below the clouds on the right is the Cretan Detachment on Psiloritis.
Agios Fanourios detachment fault. Tripolitsa rests on top of Plattenkalk metaflysch. The Tripolitsa rocks hold plenty of water (feeding the Almyros spring) which seeps out of the detachment in some places.
A mitato, a seasonal shepard’s residence. These structures don’t utilize mud or any other binding agent. Large stones are stacked in a way that provides a dry interior even in rain. Behind this building is a smaller mitato used to store and mature cheese.
Our last stop was the ophiolite at Gonies, a piece of serpentinized oceanic mantle that is the uppermost nappe of Crete. A 1 km line starting here crosses all the major units of Crete, but (even though it’s the same units) doing the same thing in northern Greece would take over 100 km!
Looking the other way from Gonies. This gorge is the longest in the Psiloritis area, but part of it is in the Heraklion basin and relatively flat. In the distance, we could see the normal faults bounding the Heraklion basin.
-Tyler and Bart
Concerns about rain and wind in the mountains caused us to rearrange the schedule. Instead of examining structures in the mountains, we skipped a day ahead and looked at geomorphic and neotectonic features along the north central part of Crete, through a gorge in a Neogene extensional basin, and along the southern coast.
The rocks here are complicated! To understand everything we were looking at, we first needed a primer on the rock units and the hypothesized sequence of events. At our first stop, Babis Fassoulas busted out the geologic map for his overview of central Crete. Today, we were concerned with 3 main units: a quartzite-phyllite schist (the QP unit), the Plattenkalk nappe, and the Tripolitsa.
The juxtaposition of these units is hypothesized as follows. First the 30-300 Ma Plattenkalk was deposited. Later it was folded and one limb was over turned. In the same collisional event, the QP unit was thrusted on top of the Plattenkalk group. This puts older rocks on top of younger ones, but with the younger Plattenkalk unit younging downward. Then Miocene extension caused exhumation and a large amount of thinning and extension in the QP unit. Finally the Tripolitsa was deposited on top of these two units. The Tripolitsa shares contacts with both units.
Within the QP unit, the extension caused shear (top to the north) in the phyllite/schist (Stop 1). Local quartz and carbonate layers were stretched into boudins. Preexisting folds from the older compressional event were also extended becoming isoclinal where they can still be made out. The QP unit was dominated by chlorites that replaced the original muscovite. Talc is also likely in this unit given the hardness of the rock, it’s white powdery streak, and very waxy talc-like feel.
Our next stop (Stop 2) was at the Plattenkalk where we observed upside coral fans within the dolomite layer that indicated that the unit was overturned. The beds were stopping gently to the north and once again we observed top to the north sense of shear in S-shaped structures (albeit more subtle than in the followed QP unit).
Then we departed the northern cost and turned south inland into one of the Neogene extensional basin, where we followed one of several isolated half-graben basins in the island’s interior. Here we saw fossils of giant bivalves (Stop 3).
The thought of clams made us all famished, but we continued bravely on to see one more outcrop before lunch (Stop 4). Many of the faults the have accommodated Neogene extension are no longer active, but we had the good fortune to look at a well studied active fault. This fault, called Spili, is known to have had 5 earthquakes of at least M6.0, and more likely M6.5 to M6.7, in the last 16,000 years.
Each earthquake has caused about 1.5 meters of offset. When this occurs, the thin soil horizon comes into contact with a new section of limestone. Soil is rich in rate Earth elements (REEs) compared to limestone, so some of the REEs diffuse into the carbonate at the surface. Researchers have used a profile in REE concentrations across the fault scarp to contain the number of events. Evidence for slip along this surface was apparent from ubiquitous slicken lines.
Then after lunch and a bit of souvenir shopping in the charming mountain village of Spili, we set off again towards the southern coast through an enormous gorge! Here (Stop 5) we took a short stroll down to the creek bed within the limestone cliffs. The karst features (namely caves) were everywhere on the sides of the gorge and in the creek bed. The water seemed to come out of nowhere, draining suddenly into the creek before quickly disappearing into a deep slot canyon. Continued uplift in Crete and rapid incision of the limestone allows for this dramatic gorge to be maintained or to continue to grow.
Our penultimate stop (Stop 6) was on the southern coast at another fault scarp. It was tall and dramatic, but as the weather shifted from overcast to partly sunny, the beautiful blues of the Mediterranean came alive and much of the group decided to take a quick swim. At this location, a careful eye could spot small pumices from the Minoan eruption that found their way to Crete!
Finally, we went to one more sheltered bay to look at a laterally continuous, horizontal notch carved into the limestone.
This feature represents the sea level before the big subduction zone earthquake in 365 AD. Here it was about 1.5 meters above present day sea level. However, in far western Crete the displacement and uplift recorded by this notch is nearly 9 meters in height! At this last outcrop, we already hunted for fossils. Among the more exciting discoveries were two ammonites and a massive deposit of centimeter wide foraminifera.
-Mike and Josh
Today is a travel day! Yes folks, that means it’s time for more on-the-road photos. I began my day with one last cup of the worlds smoothest yogurt, and one final stroll through beautiful Fira. And I saw something over the buildings…
Travel day interlude. Introducing a new section to travel day blogging: stealth profiles! Photos that only a day of travel (and lack of awareness that one is being photographed) can produce. Bonus: Factoids!
After gathering up our luggage, it was off to the hotel on a nice cushy bus. This also served as a chance for us to see Heraklion.
Next up was the Natural History Museum of Crete. First, we went over the itinerary for the next few days. Then we got to learn about the different ecological regions and biomes around the Mediterranean, rock types on Crete and in an unrelated topic, we learned about light. We also got to try out the shake table, an earthquake simulator.
We ended the night with a delicious group dinner. And group shots. Tomorrow, it’s time to hit the rocks.
-Dylan and Noah
We started our day with a visit to the Museum of Prehistoric Thera, which houses finds from the excavations of Akrotiri. There, we had the opportunity to see amazing pottery, utensils, and frescos, such as that of the blue monkeys seen below!
Above is a clay Portable Oven, 17th Century BC (Late Cycladic Period) from Akrotiri. If your pizza wasn’t delivered by donkey within 30 minutes, it was free!
Here is a gold Ibex Figurine (17th Century BC., Akrotiri). This figure was discovered in 1999, in a wooden box located in a clay chest in Akrotiri. The figure is hollow with legs, head, neck and tail soldered on. There is on-going excavation at the site where this figure was found, which will hopefully lead to new discoveries!
We then ventured off into the field, where we were buffeted by the wind. We were greeted at our first stop by an impressive church.
The stop, however, was to view Peristeria Volcano, the second stratocone constructed in the Sanotrini volcanic field (following Akrotirit). Evi and Emilie gave us an overview of the dikes that cut through Peristeria, which follow the NE-SW trend of the Kolumbo line.
Many of us took the opportunity to look at the nearby outcrops of the Skaros pyroclastic deposits.
Here we see cinder layers from Skaros eruptions (outcrop near Micros Profiitis Ilias). Layering correlates with changes in clast size, with finer clasts roughly associated with discrete, thin, layers. Curiously, the thin layering shown below merge and/or thin out further down the outcrop (see picture above). This outcrop is located near a fault zone that divides the town of Oia from the rest of Thera which strikes in a direction roughly parallel to the dikes.
We stopped for lunch at the beautiful town of Oia, located in the Northern part of Santorini. The town is largely build into Minoan eruption deposits.The characteristic windmills of Santorini are present around town.
Our final field stop of the day was to see the Cape Kolumbo tuff ring. An interesting fact – the beach shown in the photo may not exist in a given year, depending on the direction of the winter winds. If the winds primarily blow from north to south, much of the sand is transported away and the beach disappears. However, if there is a south to north wind during the winter, it will transport sand to this location and help build up the beach.
Stratigraphy of Cape Kolumbo shows the Kolumbo tuff ring as well as the first 3 phases of the Minoan eruption. Later phases of the Minoan (Phases 3 and 4) show larger lithics and violent behavior, likely a result of phreatomagmatic interactions. Phase 1 is very pumice rich with moderately sized pumice clasts. Phase 0 did not seem to be present at this outcrop.
Day three in Santorini was a full day of activities and sights. We had our breakfast of Greek yoghurt, bread, and coffee before heading out for the day.
We had planned on taking the cable car down to the harbor, but upon arrival, the gates were closed. We instead took the 587 step staircase down to the harbor, dodging donkey feces the entire way down.
The staircase from Fira to the harbor, as viewed from the boat. We took the boat from the harbor to Nea Kameni, roughly a 20 minute ride.
View of Nea Kameni from the boat.
Never trust a geologist with interesting rocks.
Learning about Nea Kameni’s 9 sub-aerial dacitic lava flows, spanning from 197 BC to 1950.
In the foreground is Nea Kameni’s 1925 Daphni Crater, in the back is the 1940-1941 Niki Dome. Note the difference ten years has on the vegetation.
Georgios Crater, erupted in 1886. The fumaroles are still active, smelling slightly of sulfur, and rich in CO2. Also, in the background is Nea Palea’s highest point.
The group is learning about Palea Kameni (old volcano). There were two lava flows that formed that island, the first in 46 AD and the second in 726 AD. The harbor has a hot spring in it that the tourists love to swim in. Aspronisi is in the background, part of the old caldera wall.
Dacite in foreground is the youngest land in Europe, from the Liatsikas eruption of 1950. The peak in the background is Mt. Profitis Ilias, the oldest exposed stone in Santorini.
A few of the 63 andesitic/dacitic dikes that penetrate the old Peristeria volcano in the caldera wall. Viewed from the boat.
After disembarking, most of us caught cable cars back to Fira. Some people missed the cable cars though, giving everyone else a well deserved break as we waited for them to arrive.
After we left the hotel a second time, we went to visit the industrial tomato factory. The photo is of the tomato paste boiler. First the tomatoes are picked, then de-leaved, pressed and crushed, boiled, then canned. This factory suffered from flooding in 1952, and from the very large earthquake in 1956.
After the Tomato Factory, we all went to the beach from the day before, to look at phase three and four of the late bronze age eruption.
After that we drove down a road to Athinios harbor, stopping to look (and collect) some low grade metamorphic rocks (blue schist).
Along the same road, we stopped (in the middle of the road), to look at the contact between the basement rocks and the volcanic material and paleosols that were deposited on top of the basement.
The last stop of the day was to see en-echelon quartz and metamorphosed conglomerate at the base of the cliffs.
-Eamonn and Will
We started the day at Metaxas (Mavromatis) quarry outcrop, which magnificently displayed all four phases of the Minoan eruption. It was rather windy, and many of us suffered some degree of corneal damage due to flying pumice (aka glass) shards.
The Quarry: All phases, 1, 2, 3, and 4, are visible here. Phases 2 and 3 comprise the tens-of-meters thick deposit seen above. Phase 4 caps phase 3 in dark grey and is several meters in thickness.
A refresher on the Minoan eruption:
The eruption began with precursory explosions that left two lapilli fallout layers and a phreatomagmatic ash (phase 0). Phase 1 is up to ~6 m thick and contains up to a few percent of andesitic scoria. The deposit is comprised of a reversely-graded unit that is overlain by a coarse, normally-graded unit.
Phase 2 deposits (seen here) include pyroclastic surge deposits with multiple beds, which can undulate or pinch out lenticularly. This deposit grades upwards into the low-grade ignimbrite of phase three, the most voluminous of the three phases. At the caldera wall, it is nearly ~60 m. Lithic blocks >1m in diameter populate the massive to crudely-bedded deposit.
At the end of the day, we went to the southern coast and got another perspective on phases 3 (the white-ish bottom layer) and 4 (the weathered brown layer above, from which holes and caves have been excavated by the wind & sea spray). Overall, the Minoan deposits are >99% rhyodacitic pumice.
Following our trip to the quarry, we ventured into illegal territory (see above sign) to check out the “red beach” – so named for the scoria cliffs that periodically collapse and extend the beach (see below).
Our third stop was archaeological, to examine the 3600-year-old ruins of Akrotiri colonized by Theracians (NOT “MINOANS”). Above is a trading post/street-side store, where goods were kept in large pots about a meter in height. The Theracians were quite a sophisticated people, having developed their own form of indoor plumbing, with toilets that piped sewage to a communal repository. Houses could be a few stories tall (higher than what is presently permitted in Santorini!). Frescoes adorned most walls and often featured seasonal landscapes.
We visited Pyrgos for lunch and walked around the city to admire the old and well preserved buildings. We saw the inside of the very newly renovated Church Theotokaki (or Panagia church) and learned about restoration processes for old paintings (circa 1800s). The church is on the highest point of the hill of the city, and stands like a fortress with a great view of Santorini. All of the roads lead up to the Church (more or less), and are small and winding with a cobbled pavement.
Outside Church Theotokaki and in the town of Pyrgos…
A collection of sights from our first day in Santorini…
Famous blue domes!
-Marisa and Ellen