Archive for July, 2012

Wooster’s Fossils of the Week: ribbed brachiopods (Middle Jurassic of Israel)

July 15th, 2012

These delightful brachiopods are from the Matmor Formation (Jurassic, Callovian) of the Negev in southern Israel. They are part of a long-term Wooster project describing and interpreting a diverse paleocommunity. The latest trip to study these fossils was this past March with Melissa Torma and our Israeli colleague Yoav Avni. The shells above are Burmirhynchia jirbaenesis Muir-Wood 1935. We identified them using the excellent work on Matmor brachiopods by Feldman et al. (2001).

The location in Makhtesh Gadol, Negev, Israel, where these specimens were collected.

Burmirhynchia jirbaensis was originally named from a collection of specimens found in the Biheh Limestone of the Jirba Range in British Somaliland (modern-day Somalia). This is a wonderful place for Jurassic paleontology, but not one I’m likely to visit soon!

Burmirhynchia is an important brachiopod in the Jurassic of the Tethyan Realm. It has been found throughout the Middle East, southern Europe, Africa and Australia. It has, apparently, been overly “split” into over 90 species, most of which are dubious at best (Shi and Grant, 1993). B. jirbaensis, though, is a legitimate species based on internal characteristics you can only see by sectioning or internal tomography (Feldman et al., 2001).

The genus Burmirhynchia was described in 1918 by an interesting character: Sydney Savory Buckman (1860-1929). Buckman is best known for his work on ammonites, but he was also a novelist, social reformer and (gasp) a fossil dealer (to support his geological work). He was born in Cirencester, England, but grew up in Dorset among some of the most spectacular Jurassic geology in the world. Buckman was briefly a farmer, but he most enjoyed amateur geology and working on collections in local museums. Ammonites were his passion — he worked on several large monographs describing hundreds of new species. (The complaints about his taxonomic splitting began then.) His most eccentric idea was that ammonites may have suffered from a kind of flatulence produced by “nervous apprehension of danger”, with the resulting gas increasing their buoyancy and helping them flee to safety. I don’t recall hearing that one in school!

Curiously enough, Sydney Savory Buckman made one progressive addition to the vocabulary of paleontology: in 1893 he invented the term “palaeo-biology” (Sepkoski, 2012).

References:

Buckman, S.S. 1918. The Brachiopoda of the Namyau Beds, Northern Shan States, Burma. Memoirs of the Geological Survey of India, Palaeontologia lndica, new series 3: 1-299.

Feldman, H.R., Owen, E.F. and Hirsch, F. 2001. Brachiopods from the Jurassic (Callovian) of Hamakhtesh Hagadol (Kurnub Anticline), southern Israel. Palaeontology 44: 637–658.

Sepkoski, D. 2012. Rereading the Fossil Record: The Growth of Paleobiology as an Evolutionary Discipline. University Of Chicago Press, Chicago, 440 pages.

Shi, X. and Grant, R.E. 1993. Jurassic rhynchonellids: internal structures and taxonomic revisions. Smithsonian Contributions to Paleobiology, Number 73, 190 pages.

The last holdouts of pagan Europe

July 14th, 2012

KÄINA, ESTONIA–The little island of Muhu between Saaremaa and the Estonian mainland, had a large prehistoric population — much larger than it has today. The Muhu Estonians built a large fort of stone heaps near the western coast opposite Saaremaa so that they could control the traffic and trade through the Small Strait. The remains of that fortification are seen above. In January 1227, Teutonic Crusaders cornered the last of the pagan Estonians in this stronghold. (They were, in fact, among the last pagans in all of Europe.) Reports say that 20,000 soldiers besieged 2500 Estonian warriors for six days here. All the Estonians were killed save one, who escaped by pretending to be a victorious crusader. Most of the stones of the fort were removed to build the causeway between Muhu and Saaremaa, but the site remains as a ring of earthen walls and a stone monument (below) marking the bloody battlefield.

Wooster geologists return to Saaremaa and Muhu one last time

July 14th, 2012

KÄINA, ESTONIA–Today the Wooster/OSU team crossed the strait between Hiiumaa and Saaremaa to visit some earlier sites one last time on this trip. The Ohio State paleontologists stayed on the northern part of Saaremaa to look for crinoids and Panga, Ninase and Undva Cliffs; the Wooster geologists went farther south and west to visit Soeginina Pank (above) and Nick Fedorchuk’s 2011 field area. This was important to us so that we could compare observations here to Richa Ekka’s exposure of these beds on the eastern side of the island.

Richa stands by Nick’s Soeginina locality to compare it to her own rocks. This Soeginina section seems considerably more dolomitized in the west than the east.

Jonah and Richa at Nick’s outcrop. Richa is pointing to the Wenlock/Ludlow boundary horizon, and Jonah is showing the stromatolite layer near the top of the section. Richa’s section in the east begins somewhere above her finger.

We were impressed by how poorly preserved the stromatolites are in Nick’s section compared to the gorgeous specimens Richa studied earlier this week. You can barely make out the laminae in this western sample. Look here at its equivalent in the east.

Another difference we noted between the Richa and Nick sections was that Nick’s has thin coral branches (above) in storm layers whereas Richa’s does not. Nick’s oncoids are also larger and more complex.

The amount of damage the Soeginina Pank outcrop received in the last year is astonishing. I had worried about our hammer blows leaving noticeable marks on the rocks. The freshly fallen blocks on the cliff above appeared since our visit last June. Much of this is likely due to ice floes slamming into the rocks during the winter.

After our observations at Soeginina Pank, the Wooster geologists drove to Muhu to visit an historical site (more later on that), then went north through Orissaare to Triigi where we reunited with our OSU companions and boarded the ferry for the ride back to our hotel on Hiiumaa. Our two matching field vehicles are seen above at the front of the ferry. We weren’t going to miss the last ferry to the island!

Quarry work continues on Hiiumaa

July 13th, 2012

KÄINA, ESTONIA–It was a beautiful Baltic day in the Hilliste Quarry on Hiiumaa. Thunderstorms swept by us to the east, but we stayed dry and enjoyed the quickly-changing cloudscape. The Wooster/OSU team was again studying the Hilliste Formation for both its crinoid content and general paleoecology. We did very well.

The typical limestone in the quarry is a biosparite/grainstone as seen above. The most common grains are bits of crinoid stems. The OSU team has found a few crinoid calices and calyx parts, but not as many as you would think given the enormous amount of crinoid skeletal debris in the unit.

It looks like a theme of this year’s Wooster study in the Hilliste Formation may be the sclerobiont (hard substrate-dwelling) fauna, especially the encrusters on corals, stromatoporoids and crinoid stems. Above you see an auloporid coral (the larger tubes connected at their bases) encrusting a favositid coral. Our other encrusters include crinoid holdfasts (three varieties), cornulitids (a kind of worm tube), sheet-like bryozoans, runner-like bryozoans (corynotrypids), and erect bryozoan holdfasts. As far as I know, no one has described a Rhuddanian sclerobiont fauna before.

We have our share of mysteries. Richa picked up the above coiled shell this morning. Bill and I have not seen anything like it in the Silurian before. If these were Jurassic rocks we would have called it a partial ammonite. We know it is not, but we don’t know what it is. A gastropod like Poleumita discors? A nautiloid cephalopod similar to Bickmorites? We’ll have to figure it out later in the lab.

Here is Jonah on the north quarry wall. We dress him brightly every day so we don’t lose him in the Estonian woods.

Richa is in her own world in the western part of the quarry looking for more paleontological treasures.

And finally, our Estonian animal of the day: a spider dutifully guarding her eggs in the quarry floor rubble. I suspect this is the Robust Crab Spider: Xysticus robustus (Hahn, 1832).
 

 

Exploring the Estonian island of Hiiumaa

July 12th, 2012

KÄINA, ESTONIA–The Wooster/OSU geology team took a break today from our usual field routine. We spent the morning consolidating notes and specimens (yes, that means the students slept very late) and then the afternoon seeing some of the major Hiiumaa sites. The highlight was visiting Hiiumaa’s iconic attraction, the Kõpu Lighthouse on the Ristna Cape. It is the oldest lighthouse in the Baltic states and reported to be the third oldest continuously-operated lighthouse in the world. It was completed in 1531 and has been working ever since. The Hanseatic League demanded a lighthouse here beside the most important trade route in the Baltic Sea. The original light was a fire that required 1000 cords of firewood every year, nearly deforesting the surrounding peninsula. The Germans bombed it in 1941, but only damaged its optical structures on top. It was an important navigational aid until 1997 when it was replaced by a modern radar system.

A model of the medieval version of the Kõpu lighthouse in the Tallinn Maritime Museum. Access to the top platform was by a long ladder. The light was a bonfire of pine wood.

The lighthouse staircase is incredibly narrow and steep, being cut into the structure in the 19th century. (Prior to this there was a wooden staircase on the outside.) Richa is better built for such a place than me!

Richa and Jonah wanted an answer to the famous “O-H-I-O” pantomime our OSU friends like to construct, so they made a C-O-W version. The lighthouse window here at the top is the “O”, you see. Maybe it will catch on. Maybe …

Near the end of the afternoon we visited the Ristna Lighhouse and one of the westernmost points on the island. (This is where Alyssa found her famous trilobite.) Richa and Jonah noted that large igneous boulders make excellent posing platforms at the edge of the sea.

As a brief nature vignette, here is a dung beetle (Geotrupes stercorosus) we saw deep in the Estonian woods at our lunch spot. I’m sparing you the dung itself!

What are the chances?

July 12th, 2012

KÄINA, ESTONIA–Today the Wooster/OSU Estonia geology team had a day of sightseeing on Hiiumaa. (More on this later.) One of our stops was the Ristna Lighthouse on the Ristna Cape in the far northwest of the island. We walked out onto a gravel spit directly opposite the lighthouse (which you can see as a red tower in the distance above). On the far western end, jutting into the Baltic Sea, Alyssa Bancroft reached down between our feet and picked up this cobble:

How amazing is that? One of the best fossils of the trip. Sure this trilobite lacks important details like stratigraphy and original location, but the story of its finding makes it a treasure!

Another new Independent Study project appears: The Hilliste Formation paleoenvironments and paleoecology

July 11th, 2012

KÄINA, ESTONIA–Today Jonah Novek officially began the fieldwork for his Independent Study research: a sedimentological and faunal analysis of the Hilliste Formation (Lower Silurian, Rhuddanian) on Hiiumaa Island, Estonia. Jonah will be continuing the work begun by Rachel Matt (’12) last year in the Hilliste Quarry a few kilometers east of Käina (N 58.87390°, E 022.97198°). He has already today been ably assisted by the generous Ohio State University crew and Richa who gave him numerous fossils they collected from the limestones and shales. Jonah and Richa completed the stratigraphic column today (essentially measurements and descriptions of the rock units, from bottom to top) and began to collect fossils from each unit. We will return at least one more day this week for continued collection.

The Hilliste Formation is very important in evolutionary and ecological studies because it records an Early Silurian “recovery fauna” that lived after the massive end-Ordovician extinctions. There are very few other shelly faunas of this age in the northern hemisphere. This may be the only one that has survived from the ancient paleocontinent of Baltica. The preservation of the fossils is excellent. Above is a heliolitid coral from the unit we have designated “Hi-2″.

Bill Ausich of Ohio State (pictured above in a heroic pose that we call “the Walcott“) found what I think is the most interesting fossil of the day in the Hilliste Quarry. His goal has been to discover as many crinoid calices as possible in the Silurian of the western Estonian islands. Finding such treasures in the Hilliste Quarry started a bit slowly, but he collected this fascinating specimen:

It is a favositid coral surface with two crinoid holdfasts attached. These holdfasts are essentially single roots with little rootlets that gripped the corallites of the coral. There is no more persuasive indicator that crinoids lived with corals here! I had not seen holdfasts like these before, which shows again the value of working with colleagues in the field.

There are also inorganic mysteries in the Hilliste Quarry. Above is an image of a bedding plane near the base of our section (unit Hi-1) that displays ripple marks in a micritic (fine-grained) limestone matrix. The compass shows the north direction, as does the measuring stick. We don’t know how ripples are formed in such a fine sediment (the particles would have been near clay size), nor what environmental forces they indicate. We do know that some show interference patterns (possibly from wave currents) and that they show similar directional orientations.

The only place in the quarry that exposes our lowest unit, by the way, has this wasp’s nest hanging over it. The wasps understandably are quite irritated by hammer blows on the rocks around them, so we must be watchful at this spot!

Good luck to Jonah as he begins his capstone college intellectual adventure. We’ll have more about this project later this week!

 

Wooster/OSU geologists move to another beautiful island with excess vowels: Hiiumaa

July 10th, 2012

KÄINA, ESTONIA–The combined Wooster and Ohio State geology team left Saaremaa Island this morning and traveled to Hiiumaa Island to the north in our search for more Silurian outcrops and their associated fossils. We drove from Kuressaare to Triigi on the northern coast to catch a 9:30 a.m. ferry to Sõru on the southern coast of Hiiumaa. It was my second visit to this island. Like every other place in Europe, it has a long history. Settlement on Hiiumaa goes back to the Fourth Century BCE. For generations the island was known by its German name: Dagö. In recent times it has been Swedish, Russian, German, Estonian, Russian again, German again, and finally part of modern Estonia.

The main attraction for the Wooster Geologists on this trip is Hilliste Quarry (seen above) in the southeastern portion of Hiiumaa. The Lower Silurian (Rhuddanian) Hilliste Formation is exposed here — one of the few in this time interval worldwide. Jonah Novek will be starting his Independent Study project here, building on the labors of Rachel Matt last year. We are all continued to search for crinoids here as part of our joint work.

Jonah is seen here in his first few minutes of examining the Hilliste Formation in our little quarry. The rocks remind me of the Cincinnatian Series because they are a sequence of bioclastic and biomicritic limestones separated by thin beds of shale. This means fossils can be exquisitely preserved on the top and bottom surfaces of the limestones where they meet the soft shales.

An example are these trace fossils preserved on the underside (“sole”) of a biosparite limestone bed. These traces are in “convex hyporelief”, meaning that they stick out on the bottom of the bed. They were formed by deposit-feeding worms of some sort. We’ll have much more on the rocks and fossils of the Hilliste Formation in later posts.

After briefly visiting Hilliste Quarry (mainly a test to see if I really remembered how to get to it), we then traveled to the southeast coast of the island (the Sarve Peninsula) in the hope that we could find some exposures of Silurian limestones. There were tantalizing hints in the limestone shingle along the eastern shore and limestone slabs at the bottom of some roads, but there were many swamps and marshes.

Sometimes we had to use the giant glacial erratics to see above the trees, as Jeff Thompson is heroically demonstrating here.

We never did find additional exposures of bedrock. In the search, though, we saw many gorgeous vistas, like this one of a coastal marsh. (Note the excellent weather, by the way.) We will have several days to continue our quest for limestone on Hiiumaa.

Whenever you wander any distance in Estonia, you find reminders of its bloody and tragic 20th Century history. Rather than repeat the war stories, I’d like to end today with a happier image of a World War II pillbox enlivened by the joyful faces of Jonah and Richa!

 

 

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!

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