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.

 

A very damp field trip

April 28th, 2012

FAIRBORN, OHIO–I actually used to brag about the great weather on my class field trips. The hubris! Today Shelley Judge and I took our combined Sedimentology & Stratigraphy and Structural Geology classes to Oakes Park Quarry near Dayton for a field trip. (Location = N39.81401°, W083.98374°.) We planned to describe and measure the exposure there of the Brassfield Formation, and then assess the joint fabric and the direction of glacial grooves on its top surface. I took three students there last week to test the concept. Since this is the last weekend of the semester, there was no do-over, so we went rain or shine.

It was 38°F and breezy when we arrived. That’s when I took my first and last picture, shown above. (It is of Tricia Hall and Scott Kugel in the middle of their stratigraphic task.) The rain came slowly at first. Not too bad. Then we heard the thunder and were quickly overwhelmed by a serious downpour. Near-freezing temperatures and a thunderstorm? That’s spring in Ohio. I haven’t been so cold and wet since I was in this place. This is why I very much prefer my field areas to be very warm and very dry.

The students were great sports, though, and we collected just enough data so that we could retreat to the bus with some geological honor intact.

The summer can’t come fast enough back here for the Wooster geologists!

Wet and Cold Wooster Geologists in the Silurian of Central Ohio

April 21st, 2012

DAYTON, OHIO–It was 37°F and raining this morning as three stalwart Wooster Geology students and I worked in a muddy quarry near Fairborn, Ohio (N 39.81472°, W 83.99471°). Our task was to scout out a beautiful exposure of the Brassfield Formation (Early Silurian, Llandovery) for a future field trip by the Sedimentology & Stratigraphy class. Until today this week was sunny and warm in Ohio. Nevertheless, our students persevered and efficiently measured and described the exposed units, and then they searched for glacial grooves and truncated corals on the top surface.

Abby, Steph and Lizzie during a relatively dry moment. The striped stick, by the way, is a Jacob’s Staff divided into tenths of meters. We use these large and simple rulers to measure the thickness of rock units. Our technician Matt Curren made us nice set of these this semester. Previous Wooster students may remember the long dowels we had in the past that Stephanie Jarvis discovered one day were not very precise! Why do we call them “Jacob’s Staffs”? Read Genesis 30:25-43. (This must be the first biblical reference in this blog!)

Dolomite at the base of the Brassfield with a pervasive fabric of burrows. These trace fossils were probably produced by shrimp-like arthropods tunneling in the seafloor sediments.

A well-sorted encrinite (limestone made almost entirely of crinoid skeletal fragments) from the lower third of the Brassfield Formation. These are mostly stem and arm pieces. The articulated portion on the left is a small stem.

A poorly-sorted encrinite. Here you can see a much greater range of bioclast size than in the previous image. There are also some brachiopod shell fragments mixed in.

The Brassfield Formation is a critical one in stratigraphy because most of the other Silurian carbonates in northeastern North America have been altered by dolomitization, which destroys the original fabric and texture of the rock. Fossils become mere ghosts in dolomitized limestone, but here they are superbly preserved.

It may have been a damp and chilly day, but how bad could it have been if we had limestones and fossils in it?

Wooster’s Fossils of the Week: Eurypterids (Late Silurian of New York)

December 11th, 2011

Few fossils are more dramatic than the long-extinct eurypterids. Above is one of Wooster’s best fossils: Eurypterus remipes De Kay 1825 from the Bertie Waterlime (Upper Silurian) of New York. (Thanks to Roy Plotnick for help with the identification.) As far as eurypterid fossils go, it is average (see Samuel J. Ciurca’s wonderful eurypterid pages for superb specimens), but for our little teaching collection it is a gem. Note that some of the fine details on the appendages are preserved.

Here’s looking at you: a eurypterid head showing the pair of compound eyes. The anterior margin “lip” indicates that this is a “carcass” specimen and not a molt fragment.

Eurypterids are commonly called the “sea scorpions” because of their long segmented body (opisthosoma), fused head segments (prosoma), sharp tail piece (telson) and claws (chelicerae). The scorpions and eurypterids, in fact, likely share a similar common ancestor. It should be no surprise to learn that eurypterids were swimming predators. The name comes from the Greek eury- for “broad” and -pteron for “wing”, referring to the large swimming appendages. Most eurypterids were relatively small like our specimen above, but some were almost two meters in length. They lived from the Ordovician to the end of the Permian Period.

Eurypterid reconstruction in Clarke and Ruedemann (1912). The artist is the famous paleontological illustrator Charles R. Knight.

Eurypterus remipes was the first eurypterid fossil formally described. The American zoologist James Ellsworth De Kay (1792-1851) did the honors while working in upstate New York. De Kay was orphaned at a young age but still managed to attend Yale (but no degree) and then complete an MD at the University of Edinburgh. He was not excited by medicine (one time he said it was “repugnant” to him), so he found himself doing many other things, such as traveling through Turkey (about which he wrote a book) and negotiating ship building contracts with emerging South American countries. Eventually he landed a job with the new Geological Survey of New York, publishing a multi-volume set called Zoology of New York State. Back then the boundaries between the natural sciences were less strict.

James Ellsworth De Kay (1792-1851)

Eurypterus fischeri (Eichwald) from the 47th plate of Ernst Haeckel’s Kunstformen der Natur (1904).

De Kay’s Eurypterus remipes was so charismatic that it became the state fossil of New York (although it took them until 1984 to declare it), and it was a global sensation in the mid-nineteenth century. Our little specimen is certainly one of Wooster’s paleontological treasures.

References:

Clarke, J.M. and Ruedemann, R. 1912. The Eurypterida of New York. Volume 1. New York State Museum Memoir 14.

De Kay, J.E. 1825. Observations on a Fossil Crustaceous Animal of the Order Branchiopoda. Annals of the Lyceum of Natural History of New York, i, 1825, p. 375, pl. 29.

Kjellesvig-Waering, E.N. 1963. Note on Carcinosomatidae (Eurypterida) in the Silurian Bertie Formation of New York. Journal of Paleontology 37: 495-496.

Tetlie, O.E. 2006. Two new Silurian species of Eurypterus (Chelicerata: Eurypterida) from Norway and Canada and the phylogeny of the genus. Journal of Systematic Palaeontology 4: 397-412.

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.

Exploring the Silurian at the Naturhistoriska Riksmuseet in Stockholm: Last day of work for the Wooster Geology Estonia Team

July 12th, 2011

STOCKHOLM, SWEDEN–No paleontological expedition is complete until it includes time in the collections of a museum. No single sampling trip like ours can describe the full diversity of a fossil site, no matter how many days we spend scouring the rocks. A traditional museum will combine the finds of hundreds of scientists over two centuries or more. The very best natural history museums, such as the Natural History Museum in London, the Smithsonian Institution National Museum of Natural History in Washington, DC, the Muséum national d’Histoire naturelle in Paris, and, of course, the Naturhistoriska Riksmuseet in Stockholm (shown above), have international collections from around the world. They set global standards for the documentation of living and extinct biodiversity. They are cathedrals of science to which we make regular pilgrimages, with all the awe and obligation that word includes.

The Naturhistoriska Riksmuseet (Royal Museum of Natural History; NRM) has the best collection of Silurian fossils in northern Europe, so we were anxious to go through the drawers and learn what we could about our own Silurian observations in Estonia. Thanks to Jonas Hagström, Senior Assistant Palaeontologist, we were given full access to the Silurian paleontology section.

Rachel Matt investigating the contents of a drawer in the NRM Silurian collections. Note the proper way of pulling open a specimen drawer: always have the drawer beneath partly open in case you accidentally pull the top drawer out too far!

The specimen drawers typically contain fossils in little cardboard trays with paper labels and a variety of stickers and numbers. Half the fun in a museum is figuring out what the organizational system is, then reading labels written in 19th Century cursive. (And in this case, in Swedish!)

Rachel making a simple photographic record of those fossils she finds that are similar to ours or should otherwise be documented for our work. Note that she has her computer open so that she can compare our field images to the museum specimens.

Nick found an excellent collection of eurypterids from the Rootsiküla Formation (Wenlock) in Estonia. He worked with these rocks in the field, but did not find any recognizable eurypterid fossils. Now he has a nice photographic collection of those in the NRM Silurian section.

After we finished our work in the collections, we toured the public displays in the NRM main building. They are fantastic. One of the highlights was this Silurian diorama showing many of our favorite extinct animals. By now you should be able to identify most of them!

Our final portrait of the trip: Nick Fedorchuk and Rachel Matt with an appropriately menacing Tyrannosaurus rex in the background. Tomorrow we leave for home! It has been an exciting adventure of science and culture.

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.

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