A beautiful day for Wooster Geologists in the Silurian of Ohio

April 18th, 2015

aDSC_5072FAIRBORN, OHIO–It’s field trip season at last for the Wooster Geologists. Several geology classes have now been out in Ohio, taking advantage of windows of spectacular weather. Today was one of those days for 25 students in the Sedimentology & Stratigraphy class. We returned to the Oakes Quarry Park exposures in southwestern Ohio (N 39.81472°, W 83.99471°). Three years ago here in April it was 37°F and raining. This year the conditions were perfect. We studied outcrops of the Brassfield Formation (Early Silurian, Llandovery) in the old quarry walls. The students measured stratigraphic columns of these fossiliferous biosparites as part of an exercise, and then explored the glacially-truncated top of the unit.

bDSC_5079The Brassfield is intensely fossiliferous. Large portions of it are virtually made of crinoid fragments. In the random view above you can see columnals, as well as a few calyx plates. This is why this unit is very popular among my echinodermologist friends at Ohio State.

DSC_5056Kevin Komara, Brian Merritt and Dan Misinay (Team Football) are here contemplating the quarry wall, planning how to measure their sections.

DSC_5063One of our Teaching Assistants, Sarah Bender, is here pointing out one of the many thin intercalated clay units in the Brassfield biosparites.

DSC_5065Fellow Californian Michael Williams directed the action. No, actually he’s doing the time-honored technique of following a measured unit with his finger as he finds a place he can safely climb to it and the units above. He is holding one of our measuring tools, a Jacob’s Staff. Why do we call them “Jacob’s Staffs”? Read Genesis 30:25-43. (Yes, today’s students are mystified by Biblical references.)

DSC_5066Here’s Rachel Wetzel, giving me a heart attack. Don’t worry, insurance companies and parents, she’s fine.

DSC_5068Rachel is again on the left. Team Ultimate Frisbee (Meredith Mann and Mae Kemsley) are in the front, and Sharron Ostermann is above. This is the recommended way to get to the top of the exposure!

DSC_5070We carried our lunches in “to go” boxes from the dining hall. Our Teaching Assistants Sarah Bender and Kaitlin Starr enjoyed a sunny picnic on the rocks.

yDSC_5077The top level of the quarry was cleared of soil and brush many years ago to expose a glacially truncated and polished surface of the Brassfield. Looking for glacial grooves and fossils here are (from the left) Tom Dickinson, Jeff Gunderson (another Californian!), Andrew Conaway, and Luke Kosowatz (who seems to also be making a little pile of rocks as a memorial to a great day).

zDSC_5074One of the many corals we found in the top of the Brassfield was this halysitid (“chain coral”), an indicator fossil for the Late Ordovician and Silurian.

Everyone returned safely to Wooster with their completed stratigraphic columns, lithological descriptions, and a few fossils. Thank you to Mark Livengood, our bus driver. Good luck to the other field trip groups later this month!

The karst topography around Guiyang, China

July 5th, 2014

Karstic Guiyang 1GUIYANG, CHINA — I find this karstic landscape enchanting. Photo taken at the airport.

Karstic Guiyang 2

A Nazi hiding hole in Middle Triassic rocks (Będzin, Poland)

June 20th, 2014

Tunnel bunker 062014SOSNOWIEC, POLAND — On my last full day in Poland, Michał Zatoń and his family took me on a tour of the city they live in and where my hotel is located: Będzin. The history of this place is very long, stretching back to the Neolithic, and for us it is dominated by World War II and the horrifying events that took place here from the earliest days of the war in 1939 until its liberation from the Germans in 1945. I thought I’d highlight one part of that history recently excavated and with a geological context.

The above view is looking down a tunnel in a complex bunker constructed by the Germans in 1944. Its purpose was to serve as a refuge from Allied bombing and reconnaissance flights near the end of the war. It had been sealed off and all but forgotten after the Germans retreated in 1945. The city of Będzin is now excavating it to be an underground museum. We were fortunate to have a private tour this morning.

Entrance bunker 062014These are the street level entrances into the bunker complex. You can see the solid rock outcrop behind the doorways.

Unfinished bunker 062014Much of the bunker is unfinished, like this portion. The steel arches are the modern effort to stabilize the roof and walls to make it safe for the public.

Fossilized cement 062014The Germans left in a hurry. This is a pile of unused bags of cement mix. In the decades since they were placed they have essentially fossilized into solid masses of concrete.

Muschelkalk bunker wall 062014This is the leading edge of construction where the concrete was laid against the rock wall. The reddish-yellow limestone is the Muschelkalk (Middle Triassic) unit we visited earlier this week. This is a strong rock suitable for tunneling because it can be easily carved out. This interval is probably equivalent to the crinoid-rich top of the Muschelkalk.

Nazis 062014This is one of the few photos made at the time in 1944 when the bunkers (although unfinished) were opened for use. It is taken from this website (in Polish). The man on the left (Hans Kowohl) was the mayor of the city, and the one in the middle was reportedly hanged as a war criminal in 1946, although I can find no mention of his identity.

Thus ends my Polish experience this summer with great colleagues, wonderful rocks and fossils, and a deep, often disturbing, history. I was challenged on many different levels.

Castles in Poland I expect, but a desert?

June 19th, 2014

Zamek Mirow 061914SOSNOWIEC, POLAND — Today my colleague Michał Zatoń took me and his family (wife Aneta and son Tomasz) on a tour of the Polish Jura, an upland with spectacular exposures of Jurassic rocks and the castles who love them. Above is the castle I consider most dramatic: Zamek Mirów from the 14th Century. Note the large mass of white bedrock at its base. This is a natural outcrop on which the castle was built. This will be a theme.

Mirow Oxfordian bioherms 061914Here we see a series of these white rocks jutting dramatically across the landscape. They are Upper Jurassic (Oxfordian) sponge-rich silicified limestones that grew as bioherms (organic mounds) on portions of seafloor elevated because of igneous intrusions below. The sponges loved being raised off the deep seabed and continued to grow upwards. Since many of them were siliceous sponges, after death their silica was mobilized into the surrounding sediment as a cement. This process produced these outcrops of very hard silicified limestones just waiting to host a castle or two.

Oxfordian limestone 061914Conveniently, the rocks can be quarried to produce the stones used in castle construction. Fossils are quite common in the building stones, like this ammonite external mold.

Zamek Bobolice 061914This is a reconstructed castle built on the outcrops.  (Zamek Bobolice; also 14th Century in origin.)

Zamek Smoleniu 061914Zamek Smoleniu was the smallest castle we visited, but somehow the scariest to climb. Getting to the top of that tower was a challenge.

Zamek Ogrodzieniec view 061914Zamek Ogrodzieniec was the largest and best known castle we visited today. It is haunted, but I ain’t scared.

Zamek Ogrodzieniec 061914The outer fortifications of Zamek Ogrodzieniec have very impressive outcrops of the Oxfordian silicified limestones.

Pustynia Bledowska 061914Now what about that mysterious Polish desert? Well, turns out it isn’t a desert in the official sense (it receives a lot of rain), but it sure looks like a desert. Pustynia Błędowska is its name in Polish. It is definitely an odd patch: 32 square kilometers in the midst of rich Polish pine forests. This place is so deserty that the German Afrika Korps trained here before going to northern Africa, and the Polish military uses it as a proxy for Middle Eastern situations. There is a lesson for humanity here as well: In the 13th and 14th Centuries the forest in this area was completely logged to provide charcoal for smelters producing silver and lead ingots. The removal of the trees exposed highly mobile glacial sands, which blew around enough to create dunes and soil too unstable for the trees to recolonize. This is a medieval ecological catastrophe. The Błędów Desert is now protected from human traffic so it has a chance to be absorbed back into the surrounding forests.

The Triassic limestones at Góra Świętej Anny, Poland

June 18th, 2014

Gora sw. Anny signSOSNOWIEC, POLAND — My friends Michał Zatoń and Tomasz Borszcz took me on a very pleasant day trip to Góra Świętej Anny in southwestern Poland about an hour’s drive northwest from Sosnowiec. This is a place of considerable geological and historical interest. It is an eroded volcanic caldera and the easternmost occurrence of the fine-grained igneous rock basalt in Europe. You would think I’d be able to show you at least a bit of basalt, but we saw only the surrounding Middle Triassic limestone country rock. (Sorry, Dr. Pollock.) We’ll talk about the history later. Now we’ll look at the geology.

Muschelkalk long 061814Here is a great exposure of the Muschelkalk, a Middle Triassic sequence of limestones and dolomites that extends across central and western Europe. This is its best exposure in Poland. The rock appears very massive in this old quarried wall, but it actually has many distinct layers. Michał is standing at the top of stairs that lead down into a massive Nazi amphitheater called a Thingstätte, but more on this later.

Muschelkalk brachs 061814Part of the Muschelkalk unit is dominated by terebratulid brachiopods, many of which are seen on this slab.

Triassic encrinite 061814The topmost Muschelkalk here contains thick beds made primarily of crinoid skeletal debris, a kind of deposit known as an encrinite. We’ve seen encrinites before in this blog.

trace fossil sign 061814You don’t often see informative signs dedicated to the description of a trace fossil type. Rhizocorallium commune is the most common ichnofossil in this part of the Muschelkalk. It is a ropy, loopy tube produced in this case by crustaceans, probably including the decapod shrimp Pemphix.

Rhizocorallium 061814The slabs used to pave the walks and plazas in this area are filled with Rhizocorallium commune traces.

View 061814Finally, this is a view west from Góra Świętej Anny towards the Oder River. It is the highest place around, dominating this fertile valley rich with farms, mines and factories. This will be the reason it is so culturally and historically significant in Silesia.

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.

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