A new Senior Independent Study project begins in Estonia

Mark Wilson June 26, 2011 2:16 pm

KURESSAARE, ESTONIA–It is always a joy to begin the fieldwork for an Independent Study project — or at least know what the fieldwork will be. This morning we visited the Soeginina Cliff locality on the Atla Peninsula of western Saaremaa and it was all we hoped it would be. Nick Fedorchuk (pictured above as a happy man with his outcrop) studied the literature about this locality during his Junior Independent Study period last semester. We confirmed today that the rocks are indeed auspicious and will work as the basis of his research.

This locality is significant because it records a time and rock boundary in the geological record. The lower portion belongs to the Wenlock Series in the Silurian System, and the upper portion is in the Ludlow Series of the Silurian. They are separated by a disconformity (an erosional horizon indicating a hiatus in the geological time record). Boundaries such as this are always interesting because they can be correlated across the globe with other rocks formed at the same time. We want to better understand what was happening in Baltica at this junction between the Wenlock and Ludlow, and then compare it to the equivalents in Sweden, Britain and North America.
The boundary rocks show a laminated unit in the uppermost Wenlock (Rootsiküla Stage) that has been interpreted as lagoonal in origin, and then a more massive limestone in the lowermost Ludlow (Paadla Stage) with oncoids (microbial accumulations) and eventually shelly beds thought to be more open shallow marine deposits. The division between them appears to be marked by a mineralized layer  (see image below). Later Nick will collect rock and fossil samples to thoroughly describe this interval and sharpen the paleoenvironmental and paleoecological hypotheses.
Rachel Matt (below) does not yet know which outcrop will be the focus of her research, but we will soon!

Our last visit of the day was to Kaarma Quarry and its exposed laminated lagoonal limestones and dolomites of the Ludlow. You can see below the team in action — and what a beautiful day it was.

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Wooster’s Fossils of the Week: Tiny little oysters (Lower Paleocene of Mississippi)

Mark Wilson June 26, 2011 1:45 am

This week’s fossils are by no means rare — last year Megan Innis and I picked up dozens of them at a muddy outcrop near Starkville, Mississippi, on our Cretaceous-Paleogene boundary expedition (click “Alabama” and “Mississippi” in the tags to the right for entries from that trip). They are, though, significant indicators of a particular kind of ecological system that appeared in the oceans of southeastern North America after the cataclysm of the Cretaceous Extinction.

The specimens pictured above are Pycnodonte pulaskiensis, a local species of oyster that belongs to a very prolific genus found around the world. Pycnodonte ranges from the Lower Cretaceous (about 140 million years ago) to, it appears, today. Kase and Hayami (1992) appear to have found this oyster — or a close relative — still living in submarine caves near Japan. This makes them a kind of “living fossil”, a group with a very long history of evolutionary stability.

This longevity fits into our Pycnodonte pulaskiensis story. These fossils are very common in the lowest Paleocene sediments just above the extinction horizon that marks the fiery end of the Cretaceous. After all that devastation (and Alabama was uncomfortably close to the impact site of Chicxulub), P. pulaskiensis appeared first to reoccupy the seafloor muds. They were virtually alone in this muddy habitat, and so lived there in great numbers. We call this kind of early successional species an “opportunist” (in the good sense!) taking advantage of a recently emptied niche.

Our little oysters in the Clayton Formation near Starkville, Mississippi.

Paul Taylor, Megan Innis and George Phillips at the Cretaceous-Paleogene boundary near Starkville, Mississippi in May 2010. Our oysters were found directly below Megan's feet.

These little oysters weren’t entirely alone, though. Many of them have small beveled holes in the center of their left valves, producing the ichnofossil Oichnus. These are apparently the traces of naticid gastropod predators (see Dietl, 2003) that drilled the holes to kill and eat the oyster soft parts.  (And who can blame them?) Several shells also have encrusting foraminiferans like Bullopora and Ramulina. Small hints of a recovering ecosystem setting the stage for the modern fauna we see in the northern Gulf of Mexico today.

References:

Dietl, G.P., 2003. Traces of naticid predation on the gryphaeid oyster Pycnodonte dissimilaris: Epifaunal drilling of prey in the Paleocene. Historical Biology 16: 13-19.

Kase, T. and Hayami, I., 1992. Unique submarine cave mollusc fauna: composition, origin and adaptation. Journal of Molluscan Studies 58: 446-449.

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Wooster Geologists return to Estonia

Mark Wilson June 25, 2011 2:40 pm

KURESSAARE, ESTONIA–Yesterday afternoon three Wooster geologists met in the Tallinn, Estonia, airport within an hour after flying from three different countries. (Thank you, travel agent Suzanne Easterling!) We rented a car and then drove through impressive rainstorms westwards to the coast where we boarded a ferry for the island of Saaremaa. By dinner time we had checked into a little hotel in the small city of Kuressaare. We are the third team of Wooster geologists to work in Estonia. The last one was two years ago — one of the first expeditions covered by this blog.

This morning we began our field reconnaissance with our friend and colleague Olev Vinn (shown below) of the University of Tartu. Olev is generously working with us for a week as we explore the Silurian and sort out Independent Study projects for senior geology students Nick Fedorchuk and Rachel Matt (pictured above). They are already prepared for work at particular sections, but we first want an overview of the Silurian on the island (and to be ready for surprises).
The Silurian of Saaremaa and its sister island Hiiumaa is very well exposed along the coastline in a series of cliffs (some of which, admittedly, are less than two meters high!). They encode information about the environments and communities on the ancient continent of Baltica about 430 million years ago. Saaremaa is particularly interesting to us because it was essentially off-limits to visitors between 1940 and 1991 because it was a military zone occupied by Soviets, and then Germans, and then Soviets again until Estonia regained its independence upon the collapse of the Soviet Union. The rocks and fossils here have not been studied as intensively as their equivalents elsewhere in Europe, so there are many opportunities for new discoveries and interpretations.
Today we visited Abula Cliff, Jaagarahu Quarry, and Elda Cliff on the western extension of the island looking at limestones and dolomites of the Wenlock Stage. Spherical stromatoporoids (see above) caught our fancy because they were particularly well exposed at Abula Cliff.

As you can see from the photos it was a gorgeous day. More geology tomorrow!
An old Soviet searchlight station at Elda Cliff (N58.30450°, E21.82935°). For twenty years now this coastline is free!

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A geological and historical tour of the Polish Jura

Mark Wilson June 23, 2011 3:44 pm

SOSNOWIEC, POLAND–A most memorable day traveling through part of the Polish Jura with Michał Zatoń and his delightful family of his wife Aneta and son Tomasz (4 and a half years old). The Polish Jura, also known as the Kraków-Częstochowa Upland, is a long exposure of Upper Jurassic (Oxfordian) limestones in southwestern Poland. We saw a bit of the rock yesterday — a hard white carbonate with a core of lithistid sponge mounds. The area is deeply eroded by karstic processes and so has vertical cliffs, pillars of limestone, sinkholes and caves. Since at least the 14th Century there have been stone fortifications (called “Eagles’ Nests”)  built on these rocks overlooking the deep valleys and access to inner Poland. One of these is the Castle of Pieskowa Skała shown above.

Michał Zatoń showing how the Jurassic limestones are used to effectively lengthen and strengthen the castle walls at Pieskowa Skała. When bedrock is used like this it is called evocatively “living stone”. A similar use of living stone was recorded in this blog two years ago from Jerusalem.

A large karstic pillar called Hercules’ Club near the Castle at Pieskowa Skała. It is juxtaposed with the castle most dramatically when viewed from down in the valley and is included in almost every early drawing or painting of the castle.

Another one of the Eagles’ Nests is Ojców Castle built in the second half of the 14th century by King Kazimierz the Great commemorating the exile and hiding in the area of his father Władysław Lokietek (called “The Elbow-High” because of his stature). The cliffs give this castle (now in ruins) an excellent view of the valley below.

The 14th Century King Władysław Lokietek mentioned above hid from his rivals in this karstic terrain. There is a legend that he took refuge in this particular cave now called “Grota Lokietka”. It is a good excuse to develop the cave into a tourist attraction. We walked through the slippery, dark and cold passages and chambers with a large crowd of enthusiastic Poles examining cave structures and listening to tales of cryptic royalty.

The third castle of the day is not in the Polish Jura, but I’ve included it for completion. It is Będzin Castle in Będzin, a small city next to Sosnowiec and the home of Michał and his family. It too was built in the second half of the 14th Century and obviously took advantage of the local geology, in this case exposures of Triassic limestones. More on the tragic history of Będzin in a later post. We had a very interesting, informative and touching tour of the city center near the end of the day.

I again want to thank my Polish paleontologist host, colleague and friend Michał Zatoń for arranging a wonderful and productive visit. I shall return with Wooster students someday soon. I am certain they will enjoy their visit and work here as much as I have.

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A delightful day in the Jurassic of Polish Silesia

Mark Wilson June 22, 2011 2:58 pm

SOSNOWIEC, POLAND–It could not have been a better day for field work: warm with a light, cooling breeze and plenty of leafy green shade. Our team consisted of me and three Polish scientists: Michał Zatoń and Wojciech Krawczyński (I work hard to get those special Polish letters in there!) of the University of Silesia, and PhD student Tomasz Borszcz of the Institute of Oceanology in Sopot, Poland (near the famed city of Gdansk on the Polish Baltic coast). Our goal was to simply see some Jurassic rocks and fossils and talk geology. Mission accomplished.

The top image shows outcrops of remarkable lithistid sponge mounds from the Oxfordian (earliest Upper Jurassic) punching up through the forest cover a few kilometers northeast of Sosnowiec. They formed relatively deep on the Jurassic seafloor and supported an associated brachiopod community.

I was able to visit for the first time one of the localities from which large Middle Jurassic oncoids (cobbles and pebbles covered with the deposits of microbial biofilms) were found and became the basis for a paper co-authored with Michał and Wojciech. In the picture above of a broken cobble you will notice bivalve borings (Gastrochaenolites) penetrating from the outside.

Lunch was in a tavern near the town square of Sławków in the Silesian Highlands. The Polish custom of carving the date of the building on the central roof beam meant we could see right away it was constructed in 1701. (It seems to be preserved in a modern shell of some kind.) I had a typical Silesian meal of rolled beef and dumplings (I think).

A view of the Silesian Highlands from a street in Sławków. This small city is the western terminus of the Broad Gauge Metallurgy Line, a rail system designed “in communist times” to transport iron ore from Ukraine to iron smelters in Poland. The rail gauge in Ukraine and points east is wider than the standard gauge in western Europe.

Our last stop of the day was to a set of deep holes in the middle of a forest. Amateur fossil collectors dug through about two meters of soil and Pleistocene sediment to expose a layer of Callovian (latest Middle Jurassic) rock rich in ammonites, belemnites and other fossils. The three paleontologists, in typical paleontological poses, are from the right Wojciech, Michał and Tomasz.

 

 

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Quality time with a Polish microscope

Mark Wilson June 21, 2011 5:06 pm

SOSNOWIEC, POLAND–A day in the lab with my colleague Michał Zatoń at the University of Silesia. We sorted through two very different paleontological problems with a microscope and a lot of hand waving. The first task was to come up with a hypothesis about the origin of the strange pitted tubes shown above. They are found on hiatus concretions of the Late Bathonian (Middle Jurassic) exposed in Zarki, Poland. We recently described and analyzed the sclerobionts on and in these concretions (see Zaton et al., 2011), but these tubes remained a mystery. We think now that they are remnants of egg cases laid by gastropods (snails) on the undersurfaces of the concretions, and we’ve started on the manuscript.

The coiled encrusting shell below is of a Devonian microconchid originally collected by the keen amateur Brian Bade in western New York and generously donated to our research. This group has some fascinating similarities and differences from its Polish cousins, so we have started a systematic project to determine if they represent a new genus or not. (Brian will be excited to hear this.)

Michal's office/lab in the Faculty of Earth Sciences, University of Silesia.

Tomorrow we set off for fieldwork in the area so I’ll post pictures of the wonderful Polish countryside!

Reference:

Zatoń, M., Machocka, S., Wilson, M.A., Marynowski, L. and Taylor, P.D. 2011. Origin and paleoecology of Middle Jurassic hiatus concretions from Poland. Facies 57: 275-300.

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Wooster Geology Majors Help with B-WISER

sjudge June 21, 2011 11:22 am

The College’s of Wooster’s B-WISER (Buckeye Women In Science, Engineering, and Research) program for 7th and 8th grade girls descended upon Scovel Hall last week for some fun activities in geology. In an afternoon session with the campers, we divided them into several groups so that they could get more individualized attention as they moved from station to station. One station, which was taught by geology major Lindsey Bowman (’12), allowed the campers to look at a variety of minerals and igneous, sedimentary, and metamorphic rocks. The focus of the station, though, was a fossil exercise in which campers tried to identify invertebrate fossils from large Ordovician rock slabs that the Mark Wilson has collected over the years. These slabs primarily contained brachiopods, bryozoans, rugose corals, bivalves, and trilobite fragments. In the image below, Lindsey (far left, blue shirt) is helping the campers identify Ordovician fossils.

The other station involved recreating a dinosaur trackway from Texas. The dinosaur tracks, as well as the stride distances between footprints, were to scale. B-WISER campers were tasked with figuring out which dinosaur was moving faster (bipedal or quadrupedal) and then coming up with a hypothesis of dinosaur behavior at the time the trackway was made. With help from William Cary (’13) and myself, campers navigated the measuring and math required to complete the task. Below is an image of the trackway in Scovel Hall; the campers are busy calculating the footprint length and stride length, while William (green shirt) is in the background helping with the activity.

At the end of the afternoon, all B-WISER campers came together for a final activity involving Plate Tectonics. Campers participated in a JIGSAW exercise created by Dale Sawyer (Rice University) in which they are divided into speciality teams: geography, seismology, volcanology, and geochronology. After analyzing data from only their specialty, mixed groups are formed so that there is at least one person from each speciality. Campers then put all of the data sets together to determine the position of the major plate boundaries on Earth. The B-WISER campers appeared to have a great time throughout the week, and geology sure enjoyed their visit!!

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Wooster Geologist in Poland

Mark Wilson June 20, 2011 2:12 pm

SOSNOWIEC, POLAND–I arrived today in Poland to work for a few days with my friend and colleague Michał Zatoń of the University of Silesia. We are going to study together some of of our favorite fossils (microconchids and other sclerobionts) and then visit local quarries in the Jurassic. This trip is supported by the Henry Luce Fund for Distinguished Scholarship at Wooster. On Friday I fly on to Estonia where I’m meeting Rachel Matt (’12) and Nick Fedorchuk (’12) for their Independent Study projects in the Silurian carbonates on the islands of Hiiumaa and Saaremaa.

Michał’s department is located in Sosnowiec, a city that is part of the Katowice Metropolitan area. (A view of an older part of Sosnowiec is shown above.) Like all of Poland, this region has a very complicated history. It was an important merchant city because of its location near the borders of the German, Russian and Austro-Hungarian Empires. Its main industries were badly damaged in World War I, and it was one of the first places occupied by Nazi Germany at the start of World War II. The heavy hand of 1950s communist architecture (large concrete block buildings) has been somewhat muted by recent renovations.

An industrial part of Sosnowiec.

Michał made certain I had a good traditional Silesian-Polish meal this afternoon. It began with a soup called “zurek” made with potatoes, hard-boiled eggs, mushrooms, tiny cubes of beef, and something that gave it an almost lemony-sour taste. Our main course was “ruskie perogi” filled with potato, white cheese, and fried onions. These apparently come from Red Ruthenia, a region now in Ukraine.

It is going to be a multicultural scientific experience this week!

The very tall Earth Sciences Department building on the campus of the University of Silesia. They take their geology very seriously here.

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Wooster’s Fossil of the Week: A chain coral (Silurian of Ohio)

Mark Wilson June 19, 2011 1:58 am

For some reason the Fossil of the Week I’ve had the most comments about is the Ordovician honeycomb coral from Indiana. It has an unexpected polygonal symmetry reflected in many other geological materials like desiccation cracks and columnar basalt. So this week’s fossil is another coral with a surprising shape: the chain coral Halysites.

Halysites is a tabulate coral genus originally named by Johann Fischer von Waldheim in 1828. Its corallum (colonial skeleton) consists of long vertical tubes (corallites) laterally attached to each other in ranks so that a cross-section looks like a series of chain links. Each corallite held a single coral polyp (an individual) that collected zooplankton for food. The spaces between the ranks — the empty holes — are called lacunae.

A closer view of the halysitid corallum. This specimen is replaced with silica so the surrounding limestone matrix could be removed by dissolving it in hydrochloric acid.

Halysites lived only in the Ordovician and Silurian (about 480 to 420 million years ago), so it is a rough index fossil for these periods. They were especially common in coral reefs, adding stability because their lacunae filled with sediment making them very difficult to dislodge by currents.

Thin-section of a halysitid coral with limestone matrix still in the star-shaped lacunae.

References:

Motus, M.-A. and Klaamann, E. 1999. The halysitid coral genera Halysites and Cystihalysites from Gotland, Sweden. GFF 121: 81-90.

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Wooster’s Fossil of the Week: A strange little echinoderm (Ordovician of Russia)

Mark Wilson June 12, 2011 1:44 am


This small fossil was completely new to me when I found it during my research trip to the Ordovician of Russia in the Fall of 2009.  A side view is shown on the left of this conical skeleton, and the top view is right.  I could tell it was an echinoderm because it has a characteristic structure in its calcitic skeleton known as the stereom (a network of tiny passageways inside the crystals).  Other than that, it was a mystery to me.

My Russian colleague Andrey Dronov showed me that it is of the genus Bolboporites, a strange relative of the crinoid found only in the Ordovician of the Baltic Region and North America.  As you can see in the reconstruction on the right below, it probably lived in the sediment as an upwardly-flaring cone with a single feeding arm (the brachiole) collecting suspended organic matter from passing water for food.  In the fossil view above and right, you can see the hole where the missing brachiole fit; inside of that you can just make out an opening that is likely the mouth.

Bolboporites likely originated on the paleocontinent of Baltica and then migrated to North America.  As far as I can tell it is vanishingly rare over here — I’ve never seen Bolboporites before in the field or in collections.  Now Wooster has one of the very few of these little treasures.

References —

Rozhnov, S.V. 2009. Eocrinoids and paracrinoids of the Baltic Ordovician basin: a biogeographical report. IGCP Meeting, Ordovician palaeogeography and palaeoclimate, Copenhagen, p. 16.

Rozhnov, S.V. and Kushlina, V.B. 1994. Interpretation of new data on Bolboporites Pander, 1830 (Echinodermata; Ordovician), p. 179-180, in David, B., Guille, A., Féral, J.-P. & Roux, M. (eds.), Echinoderms through time (Balkema, Rotterdam).

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