Archive for August, 2012

Wooster Geologists begin the 2012-2013 school year

August 30th, 2012

WOOSTER, OHIO–Always so much fun to begin a new year with the Wooster Geologists. The happy people above belong to the Geology Club in our annual group photo. This semester we are missing our treasured colleague Shelley Judge who is on a semester research leave. We also have a number of students in off-campus programs.

Here our our senior geologists. Front row from left: Joe Wilch, Richa Ekka, Anna Mudd, Whitney Sims, Kit Price; middle row: Kevin Silver, Jenn Horton, Lauren Vargo, Jonah Novek; back row: Will Cary, Melissa Torma, Matt Peppers.

Today we also posted a colorful pdf of our 2011-2012 Wooster Geology Department Annual Report, the front cover of which is shown above. You can find it at this link with our other recent reports. Thank you very much to cherished Patrice Reeder, our Administrative Coordinator, for her creativity, production skills, and detailed work. It is beautiful.

As you’ve seen in previous posts, we have newly renovated classrooms, and our courses officially began on Monday. The weather is exquisite right now in this part of the country, so we are very much looking forward to our first field trips.

Here’s to happy students and good starts!

Classes begin again for Wooster Geologists

August 27th, 2012

The happy students above are in our 8:00 a.m. History of Life course (Geology 100). They are the first class to use our newly-renovated Scovel 105 room. To remind you what it used to look like –

This new room is far more comfortable for both students and faculty. We don’t miss the 1985 color scheme either! You can see the progress made on Scovel 105 in this series of images.

Scovel 105 was first officially used for the Junior Independent Study presentation of Kit Price (’13) and the Senior I.S. presentation of Richa Ekka (’13). They each worked during the summer on their projects and gave their summaries to a group of faculty and students on Friday afternoon.

Kit Price (’13) and her very last slide. She worked on Cincinnati area fossils this summer. Note the new lecture table top.

Richa Ekka (’13), also with her last slide. She did field work in Estonia this summer.

 

Wooster’s Fossils of the Week: an enigmatic set of tubes (Middle Jurassic of Poland)

August 26th, 2012

The fossils this week celebrate the appearance of an article in the latest issue of Palaios authored by an international team led by my good friend and colleague Michał Zatoń (University of Silesia, Poland). The fossils are strange polka-dotted tubes encrusting Middle Jurassic oncoids and concretions from the Polish Jura — a place I enjoyed visiting last summer with Michał. The fossils were quite mysterious to us, but with the help of our new colleague Yasunori Kano (The University of Tokyo), we think we now have a good idea what they represent. Above you see one of the tubes on a concretion.
The polka dots are actually small, regular divots in the sides of the tubes, as shown above in this view through a scanning electron microscope. It turns out that these concavities are the same size as ooids (rounded carbonate grains) in the depositional environment. In fact, occasional ooids are still in their holes, as shown by the white arrow in the image.
In this cross-section through one of the tubes, each of the exterior holes is lined with a thin layer of carbonate, which is apparently the outer layer of an ooid that was cemented into each space. The tube itself is completely occupied by fine carbonate sediment.

Our hypothesis is that the tubes were formed by some sort of polychaete worm similar to serpulids and sabellids (with which they are associated). The worm may have built a hollow living tube by gluing ooids together and possibly taking advantage of the quick-cementing characteristics of this Jurassic calcite sea. It may have then fed on the surrounding microbial mats that covered the concretion and oncoid surfaces. This hypothesis explains the sessile nature of the tubes, their shape and construction, and their association with thin mineralized layers formed by cyanobacteria.

No polychaetes today are known to build living tubes out of ooids, so these Jurassic forms are thus far unique in the fossil and living record. It was a fun paleontological puzzle to tackle with my friends!

We are proud that our little study was chosen as the cover story for the August 2012 issue of Palaios:

“Unusual tubular fossils associated with microbial crusts from the Middle Jurassic of Poland. Upper left, an exposure of Middle Jurassic (Bathonian) clays at Ogrodzieniec in the Polish Jura; lower left, ESEM pictures of morphology and structure of the Middle Jurassic tubular fossils interpreted as remnants of agglutinated polychaete tubes; lower right, two pictures of tubular fossils encrusting oncoid and concretion; upper right, two pictures of recent agglutinated polychaete tubes from Japan.”

References:

Zatoń, M., Kano, Y., Wilson, M.A. and Filipiak, P. 2012. Unusual tubular fossils associated with microbial crusts from the Middle Jurassic of Poland: agglutinated polychaete worm tubes? Palaios 27: 550-559.

Zatoń, M., Kremer, B., Marynowski, L., Wilson, M.A. and Krawczynski, W. 2012. Middle Jurassic (Bathonian) encrusted oncoids from the Polish Jura, southern Poland. Facies 58: 57–77.

Wooster’s Fossil of the Week: a cameloid footprint (Miocene of California)

August 19th, 2012

This fossil is from near my hometown of Barstow, California. It was collected many years ago loose in talus from the Barstow Formation (Barstovian, Miocene). I note this carefully because today collecting such specimens from the Fossil Beds of the Rainbow Basin Natural Area is illegal, as it should be. This is one of the most fossiliferous Miocene deposits in the world, and it has been heavily vandalized over the years.
The Barstow Formation (in a wonderful syncline) at Rainbow Basin, Mojave Desert, California.

This two-toed footprint is Lamaichnum alfi Sarjeant and Reynolds, 1999. It is preserved as a convex hyporelief, which is essentially a filling of the actual footprint. It was made by a camel-like animal (there are many choices) that walked through stiff volcanic mud along a stream during the Miocene. The impression of this foot was quickly filled with later sediment, probably from an overbank flood.

When I was a kid we found dozens of these footprints in long trackways throughout the Barstow Formation at the Fossil Beds. Those fossils are all gone now, most lost to collectors with rock saws and sledge hammers. Fortunately many have been lovingly preserved in the Raymond M. Alf Museum in Claremont, California. You will note that the ichnospecies of our fossil was named for the charismatic Raymond Alf, a legend in the study of vertebrate trace fossils and a spectacular teacher.

Reference:

Sarjeant, W.A.S. and Reynolds, R.E. 1999. Camelid and horse footprints
from the Miocene of California and Nevada. San Bernardino Museum
Association Quarterly 46: 3-20.

Upside-down and inside-out: Cryptic skeletobiont communities from the Late Ordovician of Ohio, Indiana, and Kentucky — An abstract submitted to the Geological Society of America for the 2012 annual meeting

August 14th, 2012

Editor’s note: The Wooster Geologists in Indiana this summer wrote an abstract for the Geological Society of America Annual Meeting in Charlotte, North Carolina, this November. The following is from student guest blogger Kit Price in the format required for GSA abstracts:

Upside-down and inside-out: Cryptic skeletobiont communities from the Late Ordovician of Ohio, Indiana, and Kentucky

PRICE, Katherine W. and WILSON, Mark A., Department of Geology, The College of Wooster, 944 College Mall, Wooster, OH 44691

In the majority of the studies in which skeletobiont communities are described, they are found on the exteriors of shell substrates. Skeletobiont communities that inhabited cryptic environments inside some of these same organisms are poorly known. In those instances where cryptic skeletobiont communities have been described, they are on a much larger scale (i.e., cavities in bryozoan reefs and under hardground ledges) and do not include smaller cryptic communities. The Cincinnatian Series of Ohio, Indiana, and Kentucky has many examples of these cryptic communities. Skeletobionts encrusted the interiors of gastropod, monoplacophoran, and nautiloid shells post-mortem, and are mostly made up of sheet and runner-type bryozoans and cornulitids, along with some craniid brachiopods and microconchids. Interestingly, in contrast to other studies on skeletobionts, the majority of the encrusters in our study do not appear to have been concerned with the location of the host aperture. Only the runner-type bryozoans (Cuffeyella and Corynotrypa) appear to have some directional preference, generally increasing their crypticity and branching away from the aperture. However, increasing crypticity is not always the case; sometimes the bryozoans branch parallel to the aperture or even grew towards it. Aside from shedding light on the life habits of these encrusters, these cryptic skeletobionts also inadvertently preserved their hosts through bioimmuration. Bioimmuration is a type of fossil preservation in which a skeletal organism overgrows another, preserving its negative relief. These cryptic communities not only tell us more about the organisms living in these isolated cavities, but they also have preserved detailed external and internal molds of their host aragonitic fauna. This provides information about shell morphology that would have otherwise been lost to dissolution. Because of the abundance of skeletal bioimmuration in the Cincinnatian, a comparison of cryptic to exposed skeletobionts living in the same environments can be made.

____________________________________________________________

The header photograph is of an internal mold of a monoplacophoran mollusk. At the left you can see the branching runners of the bryozoan Cuffeyella, shown in closer view below.

Above is a close-up of the monoplacophoran internal mold. This bryozoan (Cuffeyella) was growing on the inside of the monoplacophoran shell. That shell filled with sediment and then dissolved, leaving the cemented sediment and the underside of the encrusting bryozoan. (Thus the “upside-down and inside-out” preservation.)

This is a view of the underside of skeletobionts that grew inside a nautiloid conch. The conch dissolved, leaving the undersides of various encrusters. A = the inarticulate brachiopod Petrocrania; B = sheet-like bryozoan; C = a rare microconchid with an extended apertural tube; D = another sheet-like bryozoan; E = one of many Trypanites or Palaeosabella borings.

Kit Price (’13) on one of her outcrops in Indiana (C/W-149) on July 28, 2012.

Wooster’s Fossil of the Week: a bifoliate bryozoan (Upper Ordovician of Indiana, USA)

August 12th, 2012

The specimen above is a species within the trepostome bryozoan genus Peronopora Nicholson, 1881. I don’t know which species because that would require me to slice it open and examine its microscopic skeletal details. (A reason why trepostome bryozoans are not especially popular among fossil collectors!) I found it on a recent field trip to the Whitewater Formation (Upper Ordovician, about 450 million years old) in eastern Indiana for Kit Price’s Independent Study project. Below is a photograph of the outcrop taken by Katherine Marenco (’03) — the most dramatic perspective I’ve seen for that simple roadcut!
Peronopora is bifoliate, meaning that it grew erect and budded on two sides from a central plane. Its skeleton was made of thick calcite, so it was resistant on the Ordovician seafloor during life and after death. As you can see in the close-up image below, the surface of this bryozoan is complex. It had other thin bryozoans growing on it (mainly Cuffeyella), and it was bored by worm-like organisms before and after death.

The genus Peronopora is one of the best studied trepostome bryozoans because of its thick, well preserved skeleton and abundance from the Middle through the Upper Ordovician. (Our specimen is in the Richmondian Stage and so is one of the last of its kind.) Paleontologists listed below in the references have examined in detail the colony growth (astogeny), paleoenvironments, biogeography and stratigraphic occurrences of Peronopora, making it a model for the order. My colleague Tim Palmer and I collected the genus to find beautiful examples of the bioclaustration Catellocaula vallata.

Peronopora was described in 1881 by Henry Alleyne Nicholson (1844-1899), an English paleontologist we’ve seen previously in this blog. The genus has a complicated early taxonomic history, having at one point been considered a kind of sponge.

References:

Anstey, R.L. and Pachut, J.F. 2004. Cladistic and phenetic recognition of species in the Ordovician bryozoan genus Peronopora. Journal of Paleontology 78: 651-674.

Boardman, R.S. and Utgaard, J. 1966. A revision of the Ordovician bryozoan genera Monticulipora, Peronopora, Heterotrypa, and Dekayia. Journal of Paleontology 40: 1082-1108.

Hickey, D.R. 1988. Bryozoan astogeny and evolutionary novelties: Their role in the origin and systematics of the Ordovician monticuliporid trepostome genus Peronopora. Journal of Paleontology 62: 180-203.

Nicholson, H.A. 1881. On the structure and affinities of the genus Monticulipora and its subgenera. William Blackwood and Sons, Edinburgh, 235 p.

Pachut, J.F. and Anstey, R.L. 2009. Inferring evolutionary modes in a fossil lineage (Bryozoa: Peronopora) from the Middle and Late Ordovician. Paleobiology 35: 209-230.

Grand Canyon Expedition 2012

August 9th, 2012

This summer (26 July through 2 August) I had the pleasure to serve as a guest geologist on a rafting trip to the Grand Canyon. The trip logistics were engineered by Doug Drushal under the auspices of Environmental Experiences, Inc. These trips were begun by former Wooster Geology Professor, Dr. Frederick W. Cropp III in 1980. Doug and Fred’s son Tom Cropp have continued to provide the organization and logistics for these exciting and geologically enlightening rafting trips. Special thanks to JP, our boatman, and Phil (swamper) of Hatch River Expeditions for sharing their knowledge and extensive experience of the history and geology of the Canyon.

The group poses in front of the Great Angular Unconformity. Note the tilted Precambrian Supergroup underlying the Cambrian section consisting of Tapeats Sandstone and Bright Angel Shale (see the stratigraphic section here to remind yourself of the stratigraphy). On the boat is the boatman JP and swamper Phil.

Some of the geological highlights are explained in the captions below. Not only were we treated to classic geology, but we also were able to experience and view some of the power of water in the canyon – flash floods and debris flows.

The reverse exfoliation in the Permian Esplanade Sandstone is one the the best examples of its kind. Usually when we discuss exfoliation we think of domes. The homogeneous nature of the stone along with the local stresses and erosion by the stream combine to give this unnamed side valley of the Grand Canyon such a unique (and highly photographed) look.

Springs emanating from the fractures and karst in the Redwall-Muav Limestone Aquifer provide an oasis in the Canyon and a needed water source for travelers.

Some of the group reclines on chairs in the Throne Room at Dutton Spring in the Redwall Limestone. Clarence Dutton (born in Wallingford, CT) published one of the earliest geologic studies of the canyon in 1882.

An inside-out waterfall (JP’s term). Note the encased waterfall of travertine.  Three physical effects can lead to travertine deposition at waterfall sites: aeration, jet-flow, and low-pressure effects. The three physical effects are induced by two basic changes in the water: an accelerated flow velocity, and enlargement of the air-water interface area. These two changes increase the rate of CO2 outgassing so that a high degree of supersaturation of calcite (travertine) is reached, which then induces travertine precipitation. Note also the four intrepid  explorers who facilitated the older folks into getting more involved with the water holes and falls.

 

 

Robbie reacts strongly to the Great Unconformity (aka Powell Unconformity). This gap in the geologic record is between the lower Vishnu Schist, Precambrian in age and the upper Cambrian Tapeats Sandstone. About 1 billion years is missing at the boundary where Robbie points. Think also about the burial and exhumation stages that must occur to form this, it is quite profound.

Anasazi petroglyphs – this site is dated to AD 1000-1300 and perhaps was abandoned when the Medievel Anasazi droughts descended on the region.

Anasazi ruins – perhaps this outlook spot was occupied by the higher-ups in the society with others practiced dryland farming the floodplain of the Colorado River below.

The group on the overlook point – farther up-valley another settlement is located within sight of this point.

Deer Creek falls – one of the great falls in the Canyon. This stream was rerouted when a landslide dammed the Colorado and displaced the stream. The slide occurred shortly after the damming of the Colorado River by lava flows downstream. This new lake then saturated the Bright Angel Shale, which formed the slip surface of the massive landslide.

The team scopes out lava falls a class ten rapids. Most rapids exist where side canyons bring in large boulders in debris flows that accumulate at the confluence of the tributaries and the Colorado.

A side canyon that experienced a debris flow a few weeks before our trip. In the distance is the Colorado River – it is easy to see how these rapids are evolving as flash flooding and debris flows swept boulders and debris to the river. The tributary was dry the day of our visit.

During our stay in the Canyon there was a massive storm event in the Havasu basin on 1 August. Above is the hydrograph showing the flash flood. We were unable to visit the Havisu Creek the next day because of the high flow. Below one can see the sediment and debris rich water in the Colorado River. Note also on the hydrograph that we had more than one rain event during our days in the Canyon. JP and Phil almost had to evacuate our camp as the Colorado was rising feet per hour.

The flash flood on 1 August flushed out an amazing amount of debris that included more logs and tree debris than seemed to be growing in the canyon. This beach and eddy in the distance is full of wood and debris.

Flying out of the Grand Canyon to Bar Ten Ranch by helicopter. We then took a fixed wing flight out to the Flagstaff Airport.

 

Patchiness and ecological structure in a Middle Jurassic equatorial crinoid-brachiopod community (Matmor Formation, Callovian, southern Israel) — An abstract submitted to the Geological Society of America for the 2012 annual meeting

August 6th, 2012

Editor’s note: The Wooster Geologists in Israel this spring wrote abstracts for the Geological Society of America Annual Meeting in Charlotte, North Carolina, this November. The following is from student guest blogger Melissa Torma in the format required for GSA abstracts:

TORMA, Melissa, WILSON, Mark A., Department of Geology, The College of Wooster, Wooster, OH 44691 USA; FELDMAN, Howard R., Division of Paleontology (Invertebrates), American Museum of Natural History, New York, NY 10024

The Matmor Formation is a Middle-Upper Jurassic (Callovian-Oxfordian) marl and limestone unit entirely exposed in Hamakhtesh Hagadol in the Negev of southern Israel. It was deposited in shallow marine waters very close to the paleoequator in the Ethiopian Province of the Tethyan Faunal Realm. It is very fossiliferous throughout most of its 100 meters of thickness. The Matmor Formation has been well described stratigraphically, and several of its fossil groups have been taxonomically assessed (notably the brachiopods, ammonites, crinoids and sclerobionts), but there is yet no community-level analysis of the entire fauna. This work is part of that larger paleoecological project. We systematically collected from the most fossiliferous unit of the Matmor (SU 51 in the local stratigraphy; upper Callovian; Quenstedtoceras (Lamberticeras) lamberti Zone) over several kilometers. The community in this marl is dominated by abundant crinoids (a new species of Apiocrinites), rhynchonellid (Somalirhynchia and Burmirhynchia) and terebratulid (Bihenithyris and Digonella) brachiopods, echinoids (mostly rhabdocidarids), calcisponges and scleractinian corals. Mollusks, other than small attached oysters, are relatively rare, and bryozoans are represented by only a few encrusters. The fossils are concentrated in patches a few tens of meters in diameter separated from each other by featureless, unfossiliferous yellow marl. The patches share many of the same common taxa (especially the crinoids and brachiopods) but differ in the relative abundance of corals. No infauna has been found in this unit, either as trace or body fossils. The environment appears to have been a shallow water embayment with a muddy substrate. Patches of epifauna developed as shelly islands across this seafloor. Crinoids and small corals may have been the pioneers on this soft bottom, providing increasing amounts of skeletal debris to facilitate the settlement of brachiopods and other invertebrates. A periodic influx of fine sediment during storms limited the diversity of this assemblage by smothering patches under several centimeters of mud. This community was thus kept in its early successional stages by periodic disturbance.

Wooster’s Fossil of the Week: a beautiful phacopid trilobite (Middle Devonian of Ohio, USA)

August 5th, 2012

Trilobites are always favorite fossils, especially big bug-eyed ones like Phacops rana (Green, 1832) shown above. It is, in fact, the state fossil of Pennsylvania after a petition from schoolchildren in 1988. This specimen is from the Middle Devonian of northwestern Ohio. Trilobites were Paleozoic arthropods with a hard dorsal skeleton divided into numerous segments. They look rather cute and brainy because of a swelling between the eyes (the glabella), but that space prosaically contained the stomach. Many trilobites, like this one, could roll up into balls when stressed, much like pill bugs today.

Phacops was studied by paleontologist Niles Eldredge in the early 1970s as the start of what became the theory of punctuated equilibria. The arrangement of lenses in the eyes show rapid changes in short intervals of geological time, which provided evidence for the theory he presented with colleague Stephen Jay Gould.

Phacops rana was named by Jacob Green in 1832. He called it Calymene bufo rana. Hall (1861) renamed it Phacops rana, which was confirmed by Eldedge (1972). Struve (1990) placed it in the new genus Eldredgeops (named after you know who), but I prefer the older name.
Jacob Green (1790-1841) was one of those early 19th Century American polymaths. He was a lawyer, a chemist, a physician, an astronomer, and a paleontologist. He came from a religious family, with both his father and grandfather being theologians. His father, in fact, was at one time president of Princeton University. Jacob graduated from the University of Pennsylvania at the young age of 16, and he published a treatise on electricity when he was 19. He did lawyering for a few years before becoming a professor at (you guessed it) Princeton (and later Jefferson Medical College). He published an amazing array of diverse scientific papers in his career. A trip to England introduced him to trilobites. He then spent a decade putting together a monograph on the trilobites of North America — the first ever.

References:

Eldredge, N. 1972. Systematics and evolution of Phacops rana (Green, 1832) and Phacops iowensis Delo, 1935 (Trilobita) for the Middle Devonian of North America. Bull. Am. Mus. Nat. Hist. 147:45-114.

Eldredge, N. 1973. Systematics of Lower and Lower Middle Devonian species of the trilobite Phacops Emmrich in North America. Bull. Am. Mus. Nat. Hist. 151:285-338.

Green, J. 1832. A Monograph of the Trilobites of North America. Philadelphia.

Hall, J. 1861. Descriptions of new species of fossils from the Upper Helderberg, Hamilton, and Chemung Groups. N.Y. State Cab. Nat. Hist., Ann. Rept. No. 14.

Struve, W. 1990. Paläozoologie III (1986-1990). Courier Forschungsinstitut Senckenberg 127: 251-279.

A pleasant and productive geological walk in the woods

August 1st, 2012

WOOSTER, OHIO–One of the best parts of my job is answering questions from the public about rocks and fossils. Now that I’m Secretary of the Paleontological Society, I get queries every day about something or other. (And since my brief stint on Ancient Aliens, some of my mail is predictably bizarre!) Sometimes the questions are local and students and I get to meet enthusiastic amateur geologists in the field. This morning Andy Nash (’14) and I drove a few miles north of Wooster to look at curious rocks a family had collected, and to walk through their stone-filled creek. It was delightful.

This part of Ohio has many exotic rocks scattered across its surface in Pleistocene glacial till. These rocks have their origin on the Canadian Shield and include just about every igneous and metamorphic lithology you can imagine. The family we visited had many examples of these glacial erratics. The most impressive rocks to Andy and me were pieces of the Gowganda Tillite, one of which is shown above. This rock represents lithified glacial till and is a very impressive 2.3 billion (billion-with-a-”b”) years old. This great age, plus the fact that it is a tillite within a till, makes these variegated rocks very special. The family is going to donate this one to the department, even though it will take a tractor to haul it out!

Another bonus for our brief visit was this creek exposure of the Meadville Shale Member of the Cuyahoga Formation (Kinderhookian, Carboniferous). An outcrop like this so close to campus will be useful for future paleontology field trips and maybe even an Independent Study project or two. The family that owns the land is very excited to share it. (By the way, my first paper was on a trilobite collected from the Meadville Shale in Lodi, Ohio.)

The shale outcrop is periodically broken up by floods on this little creek. Here you see scattered pieces of the gray shale, many of which have trace and body fossils in them. This shale weathers rapidly, exposing the fossils quickly. The downside of that is that the fossils are also destroyed quickly by weathering. They need the kind attention of paleontologists!

This is why we love to answer questions about geology: everyone learns in the process!

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