A paleontology field trip into the Upper Ordovician of Ohio

September 8th, 2013

DSC_2515The 2013 Invertebrate Paleontology class at Wooster had its first field trip today. The weather was absolutely perfect, and the usual boatload of fossils was collected. We traveled this year to Caesar Creek State Park and worked in the emergency spillway created and maintained by the US Army Corps of Engineers for the Caesar Creek Lake dam. Exposed here are the Arnheim, Waynesville, Liberty and Whitewater Formations of the Richmondian Stage in the Cincinnatian Series of the Ordovician System. These units are enormously rich with fossils, especially brachiopods, bryozoans, trilobites, clams, snails, nautiloids, corals and crinoids. There is no better place to get students started on paleontological fieldwork, and to follow up with lab preparation, identification and interpretation throughout the semester.

Spillway090813The Caesar Creek Lake emergency spillway is at N 39.480069°, W 84.056832° along Clarksville Road just south of the dam. The authorities keep it clear of vegetation, and so it is an extensive exposure of bare rock and sediment. The sharp southern boundary is the rock wall shown in the top image (with the intrepid Willy Nelson and Zach Downes). Students quickly fanned out along the entire exposure, so I never did get an image of the whole class of 22 students in one place.

DSC_2505This is the bedding plane of a slab of micritic limestone with numerous worm burrows. Trace fossils are very abundant here. These units, in fact, have some of the first trace fossils to be specifically described in North America.

DSC_2506On some limestone slabs are internal and external molds of straight orthocerid nautiloids. They are often paired like this, with both facing in the same direction. This is an effect of seafloor currents that oriented the shells. The current here was flowing from the left to the right.

DSC_2508Many of the limestones are extremely rich in shelly fossils. Here you can see several types of brachiopods, an isotelid trilobite genal spine, and some molluscan internal molds.

DSC_2511I always check in here with my favorite borings: Petroxestes pera. These are bivalve incisions on a cemented seafloor (a carbonate hardground). This is the type area for this ichnogenus and ichnospecies.

DSC_2512Two of our sophomore paleo students, Michael Williams and Adam Silverstein, are here happily filling their sample bags with fossils. I wanted to get a photo of them in the field because they had such a geologically adventurous summer in both cool and wet Iceland and hot, dry Utah. Not many sophomores have these opportunities!

DSC_2520Here is another pair of nautiloids, this time showing the characteristic internal mold features of curved septal walls. Again they are nestled together and oriented because of seafloor currents.

For the rest of the semester the paleo students will be studying the fossils they collected today, each eventually constructing a paleoecological interpretation based on their identifications and growing knowledge of marine invertebrate life habits and history. Now we’re really doing paleontology!

Limestones, basalts, the wine-dark sea and the brooding volcano

June 16th, 2013

1.BasaltLimestone061613CATANIA, SICILY, ITALY–Today we had our last field trip associated with the 2013 International Bryozoology Conference. We traveled to the east coast of Sicily at Castelluccio, which is south of Catania and north of Syracuse. The weather could not have been better. It was, as a commenter has said, “impossibly beautiful”.

The view above is of Early Pleistocene limestones resting on tholeitic basalt flows. As our guides said, in this place we could see the interplay of extensional tectonics, regional uplift, and glacially-controlled sea-level changes. The visuals were stunning. In the background you can see the east flank of Mount Etna.
2.Thalassinoides061613The limestones were of shallow-water origin and very diverse. One layer was almost completed bioturbated (biologically stirred up) by crustaceans, producing a trace fossil of connected tunnels called Thalassinoides.
3.FossilScallops061613Fossils were abundant in some units. Here is an horizon rich in scallop shells. These shells are often preferentially preserved because they are made of hardy calcite rather than chemically unstable aragonite like most other mollusk skeletons.
5.Dike061613The interactions between the basalt flows and the calcareous sediments were fascinated. Above you see a black basaltic dike cutting vertically through the limestones. Why there are no visible baked zones is a mystery to me.
4.BakedZone061613In this image we have basalt above and sediments below. The pink color of the limestones tells us they were cooked by the hot lava that flowed over them.
6.Beachrock061613There are a variety of post-depositional geological processes operating at this outcrop. One of them is the superimposition of beachrock during sea-level highstands. Beachrock is a cemented sediment formed in the surf zone by precipitation of carbonate. This particular beachrock was plastered onto an eroded limestone cliff like stucco. You can see black basalt among the diverse clasts.
7.EtnaBayView061613Over it all rules Mount Etna, here viewed from the top of the outcrop. It was unusually smoky today, which does not show well in our photographs because of the murky haze. We headed to this behemoth for the second and last stop of our field trip.

Pliocene marls white as snow in southern Sicily

June 6th, 2013

6. Pliocene Cliff 060613SCIACCA, SICILY, ITALY–Our last stop of the day on this International Bryozoology Association pre-conference field trip was to a massive outcrop of foraminiferan-rich marls known as the Trubi. A view of the cliffs with the sun setting behind them is above.

7. Hans Arne Pliocene 060613My colleague (and roommate on this trip) Hans Arne Nakrem is serving as a scale to show the regular cyclicity of these marls. Appropriately, he is from snowy northern Norway. These sediments were deposited immediately after the Messinian Salinity Crisis when the entire Mediterranean was reduced to a shallow series of evaporitive ponds. These marls mark the opening of the Strait of Gibraltar which flooded the Mediterranean Basin with normal seawater (the Zanclean Flood) 5.33 million years ago.

8. Pliocene Cliff 060613I wish I had better lighting to show just how brightly white these rocks are. They are now used as the base type section of the Zanclean Stage.

SicilyBeachSandHere is a late addition to this post (June 23, 2013). I collected some sand from the beach in front of these chalky rocks. A close-up image is shown above. Note that the chalk itself is eroded so quickly that it leaves no trace in the sand. We see here mostly rounded quartz grains and shell fragments.

The Lodgepole Limestone Formation

May 26th, 2013

585_LodgepoleLimestoneFormationLoganCanyonUtah052613

LOGAN, UTAH–Today we hiked up part of Logan Canyon along the south side of the Logan River. Towering above us on either side were massive limestone cliffs, as shown above. The thickest unit is the Lodgepole Limestone Formation (Lower Carboniferous, Tournaisian — about 350 million years old), which is well known throughout the northern Rocky Mountains. I’ve long admired its extent and consistency. It testifies to a shallow carbonate platform that extended from what is now Utah, and Colorado up into central Montana. In fact, correlative carbonates by other names are found from Arizona (the Redwall Limetone) well into Canada. I’ve also been impressed with those many paleontologists over the past century and a half who have managed to pry fossils out of its concrete-like matrix. When they do they have beautiful bryozoans, brachiopods and rugose corals. Some of the best are silicified and removed by dissolving the calcitic matrix from around them.

View of the northern side of Logan Canyon, Utah. The Lodgepole Limestone Formation makes up the major cliff on the right.

View of the northern side of Logan Canyon, Utah. The Lodgepole Limestone Formation makes up the major cliff on the right.

The Lodgepole Limestone Formation is part of the Madison Group of mostly limestones and dolomites. Most of these rocks are affected by karstic weathering, so the terrain often has disappearing streams, sinkholes and caverns.

While the carbonates of the Lower Carboniferous were being deposited in western North America, mixed siliciclastics dominated the east. Last semester’s Sedimentology & Stratigraphy class studied some of those rocks on their field trip to Lodi and the southern edge of Wooster, Ohio. It is always fascinating to look at very different sediments deposited at the same time in different places.

Enjoying the geology of the Mojave National Preserve

March 13th, 2013

StudentsLavaCave031313ZZYZX, CALIFORNIA–Today the Wooster Geologists explored the Mojave National Preserve. It is a beautiful, spacious, diverse place well maintained and protected by the National Park Service. Our first stop of the morning is shown above. We explored a lava tube in the cinder cones portion of the preserve. We descended into the dark tunnel by the steps above, and then studied the walls and ceiling with our flashlights, as Melissa Torma is doing below.
MelissaCave031313Lava tubes are formed when a lava flow cools on the top and sides, and then the remaining lava flows out, leaving behind the empty shell. In this particular lava tube we could see various level markings the lava left on the walls as it drained away. We also saw spatter and “lavacicles” hanging from the ceiling much like icicles or stalactites in a cave. My favorite part is where we can see from below a granitic boulder that was caught up in the flowing lava.
CambrianLimestoneOutcrop031313South of the lava tube along Kelbaker Road is a small outcrop of Cambrian limestone. We examined these rocks for a short time (above) to sort out their lithologies and the paleoenvironment in which the sediment accumulated. The clues included extensive and diverse horizontal burrow systems (shown below) and numerous oncoids with shelly nuclei.
BurrowsLimestone031313The students determined that the burrows were filled with dolomite from later diagenesis of the sediment, and that the oncoids showed the system was deposited well within the photic zone. We think this rock is a biomicrite formed around the storm wavebase on a shallow carbonate platform.

KelsoDunes031313One of our favorite places is Kelso Dunes. These massive piles of sand are stabilized at their bases but still moving about at their crests. We’ve studied them so many times in the Desert Geology and Sedimentology & Stratigraphy courses that we needed to say little about them. The students raced to the top, noting the diverse sand composition (so much more than just quartz) and eolian structures on the way.

TafoniAnanda031313Ananda Menon is here showing us one of the magnificent tuff beds at the Hole in the Wall locality in the easternmost portion of the Mojave National Preserve. The holes in the wall (is that how the place was named?) are examples of tafoni, a rock weathering pattern. We hiked the Rings Loop Trail examining the tuff units and their diverse clasts, including pumice and charcoal. We also saw good examples of Indian petroglyphs of unknown age.

QtzMonzoniteCimaDome031313While crossing Cima Dome on the way back to Zzyzx, the group visited an outcrop of quartz monzonite which forms at least part of the intrusive body under the uplift. As with most of our outcrops, it was a story of both petrology and structural deformation.

AlienFreshJerky031313Finally, at the end of the day I could not resist taking the Wooster Geologists to the unique store in Baker called “Alien Fresh Jerky“. Half the group loved it, the other seemed offended by the epic cheesiness. At least Melissa Torma and Jonah Novek enjoyed meeting members of the Galactic Peace Patrol parked in front.

Wooster Geologists return to the Mojave Desert

March 9th, 2013

DSC030913

ZZYZX, CALIFORNIA–It is officially now a Wooster Geology tradition: every other year we take a Spring Break field trip with students, faculty and staff. So far all of our trips have been to the Mojave Desert, for reasons that will be apparent in the following posts. This expedition is the highlight of our Desert Geology course this spring.  This year we have the largest group yet: eleven students, three faculty (Meagen Pollock, Shelley Judge and me — Greg Wiles could not join us because of his leave activities) and two staff (Administrative Coordinator Patrice Reeder and Geological Technician Nick Wiesenberg). We are delighted to also have with us Yoav Avni, a desert geomorphologist with the Geological Survey of Israel (and my good colleague and friend). Four vans of enthusiastic geologists!

We left Wooster very early this morning (5:30 a.m.) to catch a non-stop flight to Las Vegas from Cleveland. After picking up our vehicles at the Las Vegas airport, we drove to the Desert Studies Center (DSC) in delightfully named Zzyzx, California. We’ve stayed here many times before. The station is shown above from the mountain just to its west. Astute observers who visited this little paradise before may notice on the far right side a new solar array to supply electricity to the facility. It is all off the grid and self-contained. It feels in some ways like being on a ship at sea. On the far side of the station you can see the expanse of Soda Lake and some of the mountain ranges in the Mojave National Preserve.

NickKyle030913This year we arrived a bit earlier than usual, so we got a chance to explore the neighborhood around the DSC. Here you can see Nick Wiesenberg and Kyle Burden checking out some nearby outcrops of deformed carbonates (probably the upper part of the Bird Springs Formation, which is Permian in age). This was a chance to break in our boots and stretch our legs before settling into our quarters. The weather is overcast right now, but will dramatically improve tomorrow for the rest of the week.

The weather promises to be excellent for the week we are in the Mojave. All is well as the adventure begins!

 

Geological fieldwork on the streets of Dublin

December 16th, 2012

DublinRainbow121612DUBLIN, IRELAND — What could be more Irish than a rainbow over Dublin? (I know better than to write of leprechauns and pots of gold.)  It certainly crowned the end of a delightful afternoon spent with my friend Tim Palmer looking at building stones.

I am in Dublin attending the annual meeting of the Palaeontological Association. After a long editorial meeting, Tim and I went to the center of the city to look for a particular kind of stone that may have been used in the Medieval portions of the two Dublin cathedrals: St. Patrick’s (National Cathedral of the Church of Ireland) and Christ Church (also for the Church of Ireland but claimed by Roman Catholics — it’s confusing, especially since they are only a short walk from each other). Tim was looking for a limestone called Dundry Stone, part of the Inferior Oolite (Middle Jurassic) in Great Britain. It is notable as a non-oolitic part of the Inferior Oolite, made mostly of tiny fragments of crinoids and calcite cement. Tim quickly found the stone in both cathedrals.

StPatricks121612This is St. Patrick’s Cathedral. Its exterior is mostly restored, but the interior still retains part of its Medieval core. It dates back to 1191.

StPatricksChapelDoorway121612We asked at the door to see the oldest part of St. Patrick’s, and were immediately directed to this small chapel. At the time the cathedral was filling with people for a choir concert, so we were surrounded with the sounds of bells and children practicing their pieces. This chapel was used as a storeroom as well as a tourist site, so there are some incongruities (such as the folding chairs!). Almost all the stone is either covered with cement or replacements except in a few places, like the frame of this small doorway. That white rock is Dundry stone.

ChristChurchCathedral121612This is Christ Church Cathedral, just down the road from St. Patrick’s. (A rivalry between the two dates back to the 12th Century. Two cathedrals in one city is very rare, apparently.) Christ Church is the older of the two cathedrals, dating back to about 1040 when a Viking king of Dublin started construction. It also has a mostly restored exterior, and it too has Dundry stone making up surviving doorways and lintels.

ChapterHouse121612This is an excavated “Chapter House” just outside Christ Cathedral on the grounds. Tim Palmer can be seen in the corner making notes. Apparently monks, priests and other church notables would meet in this building and sit on the stone benches just like Tim. The stones in this ruin include original materials (like the Dundry) and a variety of other lithologies.

I had a great time learning about stonework, Medieval building techniques, and the various structural properties of limestones, all thanks to Tim. Tomorrow I’ll be back in the more secular pews of the paleontological meeting. I’m happy to have had this spot of unexpected fieldwork!

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).
 

 

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!

 

 

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