A new Independent Study project is born: The Soeginina Beds at Kübassaare

July 9th, 2012

KURESSAARE, ESTONIA–Wooster student Richa Ekka now has her Independent Study project. This is a big moment for a Wooster student: choosing the iconic capstone experience to complete the curriculum. Geologists always have delightful choices — so many possible topics and so little time! Richa decided to study the sedimentology and stratigraphy of the Soeginina Beds (lowermost Ludlow) at Kübassaare Cliff in the far east of the island (N 58.43259°, E 023.30978°) near the small village of Kübassaare. (This is the last site Olev showed us yesterday morning.) Jonah Novek and Richa are shown above carefully studying her outcrop. In Wooster geology tradition, all students on a field trip assist each other with the field work. Later this week Richa will be helping Jonah at his outcrops on Hiiumaa Island.

Richa’s goal is to thoroughly describe the rocks and fossils found at this exposure of the Soeginina Beds. She will make a paleoenvironmental interpretation, and then compare her results to those of Nick Fedorchuk (’12) who worked last year on the equivalent beds 70 km west during his Independent Study. There are some immediate clues to the general environment, such as the halite crystal mold pictured above. If halite crystals were forming, then at least part of the time there was hypersaline water about. The Soeginina Beds, though, also include various fossils, so the seawater chemistry could not have been hypersaline through all or even most of the depositional interval. This is where Richa’s bedding plane exposures give her a considerable advantage: she can detect features such as ripple marks, trace fossils, syneresis cracks and body fossils that could be easily missed in the two-dimensional cross-sections of cliff exposures.

The stromatolites, as shown above, are fantastic at Kübassaare Cliff. They are domical, most appearing to have grown as separate structures that blended laterally into single domes.

Some of the stromatolites have an odd banding, which you can see in the image above. It appears to be a color difference alone that is not reflected in the width of the laminae. One of many mysteries Richa will grapple with!

Above are some large recrystallized oval shells we found today in Richa’s section. They may be ostracods. If so, they are the largest I have ever seen. Ostracods would make sense in this very shallow environment, but so also would some bivalves.

Finally, we read in the scant literature on the Soeginina Beds that they have “eurypterid fragments”. We saw plenty of brownish flakes that could be bits of eurypterid chitin, but none had any identifiying features until Richa picked up one which clearly has the proximal segments and prosoma of a eurypterid. This is the first identifiable eurypterid I’ve ever seen in the field. Richa is proud and happy! (Even if I made her squint into the sun.)

Richa’s eurypterid. Maybe not museum quality, but far better than any I’ve ever collected! It is a good sign as Richa begins her latest intellectual adventure.

Google Earth location of Kübassaare Cliff on the eastern end of Saaremaa Island.

From east to west across Saaremaa Island’s Silurian

July 8th, 2012

KURESSAARE, ESTONIA–The Wooster/OSU Estonia team continued to explore the Silurian section on Saaremaa Island today. It was our last day with our friend Olev Vinn, and he showed us the only remaining Silurian outcrop here I have not seen: Kübassaare Cliff in the far east of the island (N 58.43259°, E 023.30978°). The image above is the crew on the hike to the outcrop. I wanted to show some of the fantastic greens on this island as a break from the limestones!

Kübassaare Cliff exposes the Soeginina Beds of the Paadla Formation (lowermost Ludlow). Thjis was exciting for me because these are the same beds Nick Fedorchuk worked on last year during his Independent Study. The Kübassaare Clff exposures, though, are many kilometers to the east and show extensive bedding planes, enabling us to find many sedimentary and paleontological features not visible at Nick’s outcrop. You will read much more about this exposure tomorrow when we return to it for a full day of work. (Our explorations today were limited by the predictable downpour of rain.)

This is the trace fossil Chondrites on a bedding plane of the Soeginina beds at Kübassaare Cliff. These traces made by deposit-feeding worms are not common in shallow sequences like this, so there is a bit of a mystery here.

The stromatolites at Kübassaare Cliff are very well preserved and visible in all three dimensions (not just cross-sections in a cliff). They do not seem to have been dolomitized like many of those in the western exposure.

Kaali Crater is a site every geologist must visit while on Saaremaa. We stopped there on our trip back across the island.. I’ve been to the crater many times and so do not need to describe it here. It is an impressive place for the freshness of the crater walls in this very damp countryside.

During the Bronze Age there was a structure built around the crater walls. Whether it was a fort or some kind of religious enclosure is not known. I only noticed today that there are still the remnants of a very mossy stone wall on the periphery of the crater.

At the end of the day we returned to the southwestern coast of Saaremaa, on the Sõrve peninsula, to Kaugatuma, site of the crinoid-rich Äigu Beds (N 58.12449°, E 022.19446°). Bill and his students found some spectacular crinoid specimens, including new calices and a kind of holdfast I had not noticed before. The rain ended (mostly) and we were able to end our day rather leisurely examining this spectacular outcrop.

Tomorrow we split up for separate field localities. The Wooster geologists are returning to Kübassaare Cliff to measure and sample the section as the centerpiece of Richa’s Independent Study project; the OSU team is heading to the northern coast of Saaremaa to collect more crinoids from the Ninase Member of the Jaani Formation. We aready know it is going to rain!

Crinoid hunting in ancient Baltica

July 7th, 2012

KURESSAARE, ESTONIA–Bill Ausich (Ohio State University) and I have a grant from the National Geographic Society to study the “origination and evolution of Middle Paleozoic crinoids on the Baltica paleocontinent“. Bill is the prime mover behind this project as one of the world’s experts on crinoids, and probably the expert on Silurian crinoids. My job is to help with the paleoecology and stratigraphic context for these crinoids. We have one paper in press now on Estonian crinoids with our colleague Olev Vinn of the University of Tartu. The above photo shows our team this morning looking for crinoids in the Ninase Member of the Jaani Formation at the Undva Cliff on the northwestern tip of Saaremaa Island (N 58.51679°, E 021.91727°).

The full team includes Wooster students Jonah Novek and Richa Ekka (introduced before), Ohio State University graduate students Mark Peter and Alyssa Bancroft, and OSU undergraduate Jeff Thompson. Along with finding crinoids, the Wooster students will also be developing their Independent Study field projects. This is why our work is also supported by the Wengerd Fund at The College of Wooster.

Today we met Olev Vinn (and his wife Ingrid and two delightful children, Sigrid and Erik) and explored three outcrops looking for crinoids, especially their elusive calices (essentially their heads). Above is a calyx of Eucalyptocrinites showing partition plates. We found many more such beauties, especially at Undva Cliff.

Rain is going to be a fact of field life in the next week at least. The weather can apparently change rapidly on the Baltic coast. The above storm appeared to the west of us in mid-morning at Undva Cliff. Since the wind was blowing to the west, it didn’t seem an issue. The wind direction changed 180°, though, and quickly brought the deluge upon us. We ran back to our vehicles but were completely soaked. Lesson learned!

Our second outcrop was the Ninase Member again on the western shore of Tagalaht Bay at a place called Kuriku Cliff (N 58.50282, E 022.01284). You can see us above scattered along the cliff face.

The preservation of the fossils at Kuriku Cliff is mixed. Some calcitic forms are exquisite, especially brachiopods and crinoids. Others, like the favositid coral above, are recrystallized. In this case the corallites filled with calcite and then dissolved, leaving an odd kind of internal mold.

Our last outcrop was Kogula Quarry (N 58.28589°, E 022.26053°), where road gravel is made by progressively crushing limestones from the Silurian (Ludlow) Paadla Formation. Saturday was a good time to visit this quarry because it was closed and not operating. We found many fossils here, especially mollusks. The crinoids, though, were only rare bits and pieces.

Except for that morning drenching, it was a very good paleontological day. The Wooster students have been well introduced to Silurian limestones in general and Saaremaa stratigraphy in particular. Tomorrow we will see what Olev says is the only outcrop on Saaremaa I have not visited. That will complete our tour and we can then begin to do our detailed work. Now we know to run for cover as soon as we feel the wind quickly change!

 

Silurian limestone under our feet

July 6th, 2012

KURESSAARE, ESTONIA–The 2012 Wooster Estonia expedition had its first official time in the field this afternoon. Jonah, Richa and I traveled the short distance from Kuressaare to the historical Sõrve peninsula in the extreme southwest of Saaremaa. There we explored the Äigu Beds in the Kaugatuma Formation exposed along the peninsula’s northwest coast. I know this place well from several visits, and it was the site of Palmer Shonk’s Independent Study project. The limestone here is mostly a high-energy encrinite (a rock made almost entirely of crinoid fragments) with many elaborate crinoid root systems in place showing the arrangement of a “crinoid forest”. Pictured above is a limestone bedding plane with two primary axes of the roots  (holdfast) of the genus Enallocrinus. The interior sediment has eroded away so that you can see the holes where “rootlets” emerged to penetrate the surrounding sediment.

Richa and Jonah on the swampy northwest side of the peninsula with the Kaugatuma Cliff exposed in the background.

Our liberally-educated students are here examining the surface of a granitic boulder brought here from Sweden by the last glaciation and dropped as an erratic. Of course, it is not the igneous rock that excites them — it’s the multicolored  lichens on it!

This project is funded by a grant from the National Geographic Society and the Wengerd Fund of The College of Wooster. Tomorrow we will introduce you to the Ohio State University team members and more details about our work and goals. We are very grateful for this research opportunity. We are also very pleased with the spectacular weather. Sunny and 26°C today.

 

Wooster Geologists return to Estonia

July 6th, 2012

KURESSAARE, ESTONIA–It took longer than we expected, but three Wooster geologists and four colleagues from Ohio State University are finally on the island of Saaremaa and ready for our fieldwork in the Silurian limestones along the shores here and on the smaller island of Hiiumaa to the north. We had a missed connection which delayed us a day in Tallinn, and everywhere we went our reservations were difficult to find, but it has at last worked out. Above you see Richa Ekka and Jonah Novek, two Wooster seniors who will be studying the Silurian sections for their Independent Study theses. Behind them is Moon Sound between the Estonian mainland and Muhu Island as viewed from a car ferry. Richa and Jonah are part of a long tradition of Wooster students who have worked in Estonia, some of whom you can meet by clicking our Estonia tag to the right.

Now we’re off to buy some lunch and take advantage of the fantastic weather to see some rocks. Much more will follow!

The view from my hotel room of Kuressaare Castle. Nice, eh?

First Wooster student presentations: The Estonia team

October 9th, 2011

MINNEAPOLIS, MINNESOTA–The first Wooster students presented today at the Geological Society of America annual meeting. Above is Nick Fedorchuk who talked about his work in Estonia studying the Wenlock-Ludlow boundary on Saaremaa Island and its implication for Silurian stratigraphy and depositional environments in Baltica.

Rachel Matt (above) presented her work on the Lower Silurian fauna found in the Hilliste Formation on Hiiumaa Island, Estonia. These fossils are critical evidence for the recovery of marine communities following the end-Ordovician mass extinctions.

It was fun watching Nick and Rachel interact with geologists who stopped by to see their posters. Not only did they learn a great deal about the rocks and fossils they are studying, they could also see how they fit into larger questions about Silurian plate tectonics and evolution.

Two other Wooster students also showed posters today: Lindsey Bowman and Andrew Collins. Photos and profiles of their work will be posted later.

A Day in Tallinn, Estonia

July 10th, 2011

TALLINN, ESTONIA–Like our Wooster Geology colleagues in Iceland, we also have a nearly-final day in a city. Tallinn is the capital of Estonia, the medieval town square of which is shown above. We started here briefly at the airport, and will leave from the same place early  tomorrow morning. The only difference is that we have one more big city to go: Stockholm, Sweden.

Tallinn, or at least a significant settlement in this place, goes back to the 11th Century, and before that there are Bronze Age artifacts. After the Danes conquered it in the 13th Century, it became known as Reval until the Estonian War of Independence in 1918-1920 when the Estonians could finally give it their own name: Tallinn (or Tallinna). It was a member of the Hanseatic League, being an important trade link between northern Europe and Russia. (And so the merchants in the town square are dressed in the Medieval garb of “Old Hansa”.) This year it is a European Capital of Culture. Tallinn does not sit on a major river but takes advantage of Ordovician limestone heights to raise it above the coastal swamps and bogs.

We enjoyed a day off in the city under (as you might have predicted) sunny skies. Tomorrow is another travel day, and then back to work one more time in Stockholm!

The newly renovated Freedom Square in Tallinn. The memorial is for the Estonian War of Independence (1918-1920).

Rachel and Nick can be barely made out here on the other side of Freedom Square.

Suur Strait (Moon Sound, Moonzund)

July 9th, 2011

TALLINN, ESTONIA–The Wooster Geology team in Estonia successfully returned to the Estonian capital city of Tallinn today, which means we crossed by ferry the Suur Strait between the western Estonian islands (notably Muhu) and the Estonian mainland. This is an interesting strip of water with a complicated geological and human history.

There is an Estonian dream of building a bridge or digging a tunnel across the Suur Strait to eliminate the need for the ferry line and more efficiently connect Muhu and Saaremaa to the main part of Estonia. It will not be an easy task (and it is probably too expensive to ever be attempted), but it has led to considerable study of the strait and its oceanographic, biologic and geologic characteristics. The currents are complicated as they move between the Gulf of Riga to the south and the Baltic Sea proper in the north, and it freezes solid in the winter (when it is crossed by a 9 km long ice road). The strait hosts one of the most significant bird migration routes in northern Europe, and the marine fauna and flora here is still poorly surveyed.

The floor of the Suur Strait is highly variable from exposed Silurian limestone bedrock to thick mantles of glacial till. As you can deduce from the Google Earth image, some parts of the strait are very shallow, and the deepest regions are no more than 21 meters of water. Because of isostatic rebound, the region gets shallower about 2 mm per year as the land rises.

Suur Strait as viewed from northeastern Muhu (July 2007).

Historically, the Suur Strait has been the “backdoor” to the Gulf of Riga to the south. Any navy that controls the Baltic wants to keep that backdoor open for itself, but close it to enemies. This was especially the case during World War I when the Imperial German Navy sought to trap elements of the Imperial Russian Baltic Fleet in the Gulf on October 17, 1917, during Operation Albion. Most escaped north through the Suur Strait (known then in English as Moon Sound) following carefully dredged channels lined with mines. One Russian battleship, the Slava, was severely damaged and took on too much water to pass back through the shallow strait and was scuttled.

The Suur Strait was crossed by the Germans in 1941 as they invaded the western Estonian islands (Operation Beowulf), and again by the Russians when they re-invaded in 1944 (Moonzund Landing Operation).

We made it across on one of the car ferries which ply the Suur Strait between Kuivastu and Virtsu. Like the Russian warships of old, it also follows a dredged channel through the shallow and storied waters.

View from our ferry west across the Suur Strait towards Kuivastu on Muhu island. Last ferry ride of the trip!

Reference:

Saaremaa Fixed Link – Report of Preliminary Environmental Impact Assessment – Final Draft – 15.07.2005 (Google this and you can get a thorough report as a pdf.)

A visit to Kaali Crater for our last day on Saaremaa

July 8th, 2011

KURESSAARE, ESTONIA–A dramatic geological site on our last Saaremaa day: the meteorite craters at Kaali. We hiked around the largest crater (shown above) and then visited one of the smaller subsidiary craters nearby (shown below). The main Kaali crater is 110 meters in diameter and about 22 meters deep. The meteorite was between 20 to 80 metric tonnes and was traveling 10-20 km/s. It broke up into pieces 5-10 km above the ground before the multiple impacts. The date of this event is disputed. We have seen ranges in the literature from 4000 to 2700 years ago. Some archaeologists have evidence that an ecological catastrophe followed the impacts with massive wildfires and a drop in crop production for a century. Others think there is a connection between the Kaali event and Baltic mythology. (I think it is a delightful coincidence that the Estonian place name “Kaali” used for this fiery event is coincidentally the same name as the fearsome Hindu goddess.)

To our surprise, the Kaali Museum had a thorough display on the geology of Saaremaa, including this polished cross-section through Nick’s critical Wenlock/Ludlow section.

Our last stop was a virtually abandoned little harbor at Turja on the southeastern coast of the island. It was a nice place for lunch as we contemplated how our fieldwork did not include bears and wolverines (as with our Wooster colleagues in Alaska) or gale-force winds and thick fogs (as experienced by our Iceland friends). We were quite fortunate to gather such excellent geological data with so few such adventures!

Tomorrow we drive to Tallinn to spend a day and a half, and then to Stockholm for a day in the Natural History Museum looking at comparative Silurian material. On Wednesday of next week we fly home.

Paleoecology of the Hilliste Formation (Lower Silurian, Llandovery, Rhuddanian) Hiiumaa Island, Estonia: An example of a shallow marine recovery fauna — An abstract submitted to the Geological Society of America for the 2011 annual meeting

July 7th, 2011

KURESSAARE, ESTONIA–Editor’s note: The Wooster Geologists in Estonia found enough material, and had enough time, to write abstracts for posters at the Geological Society of America Annual Meeting in Minneapolis this October. The following is from student guest blogger Rachel Matt in the format required for GSA abstracts:

PALEOECOLOGY OF THE HILLISTE FORMATION (LOWER SILURIAN, LLANDOVERY, RHUDDANIAN) HIIUMAA ISLAND, ESTONIA: AN EXAMPLE OF A SHALLOW MARINE RECOVERY FAUNA

MATT, Rachel M., WILSON, Mark A., FEDORCHUK, Nicholas D., Dept of Geology, The College of Wooster, 944 College Mall, Wooster, OH 44691-2363, VINN, Olev, Dept of Geology, University of Tartu, Ravila 14A, 50411 Tartu, Estonia

The Hilliste Formation (Lower Silurian, Llandovery series and Rhuddanian stage) is well exposed in a quarry in western Estonia. During the deposition of this unit, Estonia was part of the paleocontinent Baltica, which was located near the equator. The Hilliste Formation thus records the recovery of tropical invertebrate marine communities following the mass extinction at the end of the Ordovician. Globally, pre-extinction levels of marine diversity were not met until the Wenlock, about 15 million years after the end of the Ordovician; this formation was deposited about three million years following the event. The Hilliste Formation contains a diverse fauna including brachiopods (orthids, atrypids, rhynchonellids, pentamerids, and strophomenids), corals (favositids, halysitids, heliolitids and rugosans), stromatoporoids, bryozoans, gastropods, crinoids, ostracodes and trilobites. We measured, described and sampled the Hilliste Formation at Hilliste Quarry on Hiiumaa Island, western Estonia. The unit records a regression from depths between normal and storm wavebase to depths at or above normal wavebase. The evidence for this paleoenvironmental interpretation includes more argillaceous beds in the bottom two-thirds of the formation and more biosparite/grainstone upwards. The top third of the formation consists of massive biosparite/grainstone with little clay and overturned and fragmented corals and stromatoporoids indicating high depositional energy. The fauna changes stratigraphically upwards from one dominated by brachiopods and gastropods to a community primarily of corals, stromatoporoids and crinoids. This fauna provides additional information about biotic recovery in eastern Baltica and its implications for the migration of Early Silurian Baltic taxa into other regions.

« Prev - Next »