Last day of the Larwood meeting: Museum collections and a coal mine tour

June 8th, 2018

Cardiff, Wales — On our last day of the Larwood Meeting, we finished up business in the morning and then had guided tours of the marine, mollusc, and fossil collections in the National Museum Wales (above).

Highlights for me included this modern gastropod shell (a cold-water whelk from Alaska) collected by my hero Captain James Cook in 1778 a year before he was killed. A quote from Cook: “Ambition leads me … farther than any other man has been before me”. James Kirk of Star Trek is partly modeled after him.

Here’s another evocative modern shell: Conus gloriamaris, once thought to be the rarest shell and thus enormously valuable.

Here is the label for the specimen. It lists the 12 known specimens at the time. It is still popular among collectors, but now much more common. The excellent mollusc type collection of the Cardiff Museum is online.

The last activity for the Larwood crew was a tour of a coal mine turned into a museum: The Big Pit. Coal in South Wales played a huge role in the Industrial Revolution, as did Welsh iron ore. This mine tells the story of coal in Wales by taking visitors underground into the workings.

We couldn’t take images in the mine itself because of fire hazards, but Hans Arne Nakrem got a shot of the group prepared to go down the shaft. We had a great time with our story-telling guide. Our walk through the tunnels was punctuated by the loud bangs of my helmet on the ceilings. (It’s not just that I’m tall — it’s also that I bend far less!)

And that was the end of the 15th Larwood Meeting. Thank you again to Caroline Buttler and her team for such an excellent event. We all learned more about our precious bryozoans, with the bonus of getting to explore parts of beautiful South Wales.

Bryozoologists on the rocks in South Wales

June 7th, 2018

Cardiff, Wales — There is a tradition at bryozoology meetings that we get out into the field as a group. Caroline Buttler (our organizer) and Lesley Cherns (Cardiff University) took us during the afternoon to two sites. The first (shown above) is the excellent Carboniferous-Triassic-Jurassic section at Ogmore-by-Sea. Tim Palmer took me here on an epic field trip three years ago, and my blog post from then has some of the important geological details. Basically, we have an extensive exposure of the Carboniferous Limestone (High Tor Limestone, Dinantian in age), topped by an unconformity with Triassic wadi deposits in some places and a Jurassic limestone (Sutton Stone, Hettangian). The group above is scampering about on an exposure of the Carboniferous Limestone.

Here the bryozoologists are examining the unconformity between the Carboniferous Limestone (which they’re standing on) and the Jurassic Sutton Stone above.

Andrej Ernst (University of Hamburg) managed to find tiny bryozoans in the Carboniferous Limestone.

Hans Arne Nakrem (University of Oslo; Natural History Museum) and me looking studious with the Carboniferous Limestone.

The Carboniferous Limestone has fantastic sections through large rugose corals.

The trace fossil Zoophycos (“rooster tails”) is also common in the Carboniferous Limestone.

Our second stop was at an Upper Triassic section at The Bendricks along the coast. Here we see desert and flash flood deposits with … wait for it …

… dinosaur footprints! One rather battered example of a print from a three-toed theropod dinosaur is shown above. (Grallator is the ichnogenus.) These were among the earliest dinosaurs, so seeing such a trackway is very cool. You can read here a detailed assessment of the tracks.

Thank you again to Caroline Buttler and Lesley Cherns for arranging this fun trip.

A geological and archaeological hike in northeastern Ohio on the last day of winter

March 19th, 2018

It was a beautiful latest-winter day in Wooster. Nick Wiesenberg had the great idea of taking an afternoon to hike through Pee Wee Hollow, a wooded area of ravines, streams and rocky exposures a few miles northwest of Wooster near the village of Congress. Greg Wiles, his faithful dog Arrow, and I went along. We had an excellent time with no agenda but to explore. Above is Dr. Wiles standing at an outcrop of Lower Carboniferous sandstones, shales and conglomerates making up the Logan Formation. The rocks are similar to those exposed in Spangler Park.

Pee Wee Hollow has three small Native American mounds on an upper plateau. Nick and Arrow are standing on one above. They were excavated in the 1950s, and possibly pillaged long before that. Dr. Nick Kardulias, Dr. Wiles and several others wrote a paper on these mounds. I can quote the abstract entirely: “While a great deal is known about the many earthworks of central and southern Ohio, there is a gap in our data about such features in the northern part of the state. The present report is an effort to bring work on one such site in Wayne County into the literature. The Pee Wee Hollow Mound group consists of three small circular earthen structures and a possible fortification trench on a high bluff overlooking the main stream that drains the county. Systematic excavation by avocational archaeologists in the 1950s revealed the structure of the mounds and retrieved a small assemblage of artifacts, some charcoal, and pockets of red ochre. Recent analysis of the artifacts, coupled with radiocarbon dating, indicates that the site was a location of some local importance from the Late Archaic through the Middle to Late Woodland periods.” (Pennsylvania Archaeologist 84(1):62-75; 2014)

Another of the mounds with Greg and Arrow for scale.
The very fine sandstones of the Logan Formation are especially well exposed in the creek beds. Here are a set of joints our structural geologist Dr. Shelley Judge would appreciate.

There are even some nice Bigfoot field structures. Who knew?We spent most of our time walking up Shade Creek. The creek bed is mostly Logan Formation sandstones.

Greg is standing here on a bedding planes of sandstone with nice ancient ripple marks. Note, by the way, the chunk of ice above his head. Still winter, but not for long.

Here’s a closer view of those ripples.Arrow here contemplates a thick exposure of dark gray shale. Greg found some nice crinoid columns in it, and I found several molds of bivalves.

The more resistant units in the Logan have the best fossils. This slab of very fine sandstone cemented with iron carbonates (a type of siderite concretion) has several internal molds of brachiopods and white calcitic crinoid columns. I described the remarkable preservation of similar crinoids in an earlier series of blog posts.

A nice, uncomplicated walk in a beautiful bit of nature.

Wooster’s Fossils of the Week: Chaetetids from the Upper Carboniferous of Liaoning Province, North China

September 22nd, 2017

1 Benxi chaetetid 2a 585Three years ago I had a short and painful trip to China to meet my new colleague and friend Yongli Zhang (Department of Geology, Northeastern University, Shenyang). The China part was great; the pain was from an unfortunately-timed kidney stone I brought with me. Nevertheless, I got to meet my new colleagues and we continued on a project involving hard substrates in the Upper Carboniferous of north China. Above is one of our most important fossils, a chaetetid demosponge from the Benxi Formation (Moscovian) exposed in the Benxi area of eastern Liaoning Province. We are looking at a polished cross-section through a limestone showing the tubular, encrusting chaetetids. This month the paper on these fossils has at last appeared.
2 Chaetetid Benxi Formation (Moscovian) Benxi Liaoning China 585This closer view shows two chaetetids. The bottom specimen grew first, was covered by calcareous sediment, and then the system was cemented on the seafloor. After a bit of erosion (marked by the gray surface cutting across the image two-thirds of the way up), another chaetetid grew across what was then a hardground that partially truncated the first chaetetid. This little scenario was repeated numerous times in this limestone, producing a kind of bindstone with the chaetetids as a common framework builder.
3 Chaetetid Benxi cross-section 585Here is the closest view of the chaetetids, showing the tubules running vertically, each with a series of small diaphragms as horizontal floors.

Last week’s fossil was a chaetetid, introducing the group. They are hyper-calcified demosponges, and the classification of the fossil forms is still not clear. Their value for paleoecological studies, though, is clear. This particular chaetetid from the Benxi Formation preferred a shallow, warm, carbonate environment, and it was part of a diverse community of corals, fusulinids, foraminiferans, brachiopods, crinoids, bryozoans, gastropods, and algae. Such hard substrate communities are not well known in the Carboniferous, and this is one of the best.

References:

Gong, E.P, Zhang, Y.L., Guan, C.Q. and Chen, X.H. 2012. The Carboniferous reefs in China. Journal of Palaeogeography 1: 27-42.

West, R.R. 2011a. Part E, Revised, Volume 4, Chapter 2A: Introduction to the fossil hypercalcified chaetetid-type Porifera (Demospongiae). Treatise Online 20: 1–79.

West, R.R. 2011b. Part E, Revised, Volume 4, Chapter 2C: Classification of the fossil and living hypercalcified chaetetid-type Porifera (Demospongiae). Treatise Online 22: 1–24.

Zhang, Y.L., Gong, E.P., Wilson, M.A., Guan, C.Q., Sun, B.L. and Chang, H.L. 2009. Paleoecology of a Pennsylvanian encrusting colonial rugose coral in South Guizhou, China. Palaeogeography, Palaeoclimatology, Palaeoecology 280: 507-516.

Zhang, Y.L., Gong, E.P., Wilson, M.A., Guan, C.Q.. and Sun, B.L. 2010. A large coral reef in the Pennsylvanian of Ziyun County, Guizhou (South China): The substrate and initial colonization environment of reef-building corals. Journal of Asian Earth Sciences 37: 335-349.

Zhang, Y., Gong, E., Wilson, M.A., Guan, C., Chen, X., Huang, W., Wang, D. and Miao, Z. 2017. Palaeoecology of Late Carboniferous encrusting chaetetids in North China. Palaeobiodiversity and Palaeoenvironments https://doi.org/10.1007/s12549-017-0300-5

Wooster’s Fossil of the Week: a medullosalean pteridosperm (Upper Carboniferous of northeastern Ohio)

May 5th, 2017

It is time we had another fossil plant in this series. The above specimen is Neuropteris ovata Hoffmann 1826, a relatively common bit of foliage in the Upper Carboniferous of North America. This is a pteridosperm, more commonly known as a seed fern. They weren’t really ferns at all but fern-like plants with some of the first real seeds. They are usually reconstructed as trees, but were also known to be bushy or even like climbing vines.

The taxonomy (naming system) of fossil plants can be very complicated because different plant parts were given different names at different times. A single plant species, then, could have a list of names for its foliage, bark, roots, seeds, etc. The name Neuropteris usually thus refers to the leaves of this particular pteridosperm.

Neuropteris ovata is famous for its use in studies of the distribution of stomata on its leaf surfaces. Stomata, sometimes called guard cells, regulate gas exchange and moisture retention in vascular land plants. The density of stomata on N. ovata leaves in the Late Carboniferous may reflect changes in carbon dioxide levels and the expansion and contraction of tropical forests (Cleal et al., 1999).

Neuropteris ovata was named by Friedrich Hoffmann (1797-1836), a Professor of Geology at the University of Berlin. I wish I knew more about him because not only did he do considerable paleobotanical research, he was also well known for his work on volcanoes in Italy. You don’t see that combination very often!

References:

Beeler, H.E. 1983. Anatomy and frond architecture of Neuropteris ovata and N. scheuchzeri from the Upper Pennsylvanian of the Appalachian Basin. Canadian Journal of Botany 61: 2352-2368.

Cleal, C.J., James, R.M. and Zodrow, E.L. 1999. Variation in stomatal density in the Late Carboniferous gymnosperm frond Neuropteris ovata. Palaios 14: 180-185.

Hoffmann, F. 1826. Untersuchungen über die Pänzen-Reste des Kohlengebirges von Ibbenbühren und von Piesberg bei Osnabrück. Archiv für Bergbau und Hüttenwesen 13: 266-282.

Zodrow, E.L. and Cleal, C.J. 1988. The structure of the Carboniferous pteridosperm frond Neuropteris ovata Hoffman. Palaeontographica Abteilung Palaophytologie 208: 105-124.

[Originally posted on October 23, 2011.]

Wooster’s Fossil of the Week: A Conulariid (Lower Carboniferous of Indiana)

April 14th, 2017

I have some affection for these odd fossils, the conulariids. When I was a student in the Invertebrate Paleontology course taught Dr. Richard Osgood, Jr., I did my research paper on them. I had recently found a specimen in the nearby Lodi City Park. It was so different from anything I had seen that I wanted to know much more. I championed the then controversial idea that they were extinct scyphozoans (a type of cnidarian including most of what we call today the jellyfish). That is now the most popular placement for these creatures today, although I arrived at the same place mostly by luck and naïveté. (I love the critical marks in that word! And yes, I always have to look them up.)

The specimen above is Paraconularia newberryi (Winchell) found somewhere in Indiana and added to the Wooster fossil collections before 1974. (The scale below it is in millimeters.) A close view (below) shows the characteristic ridges with a central seam on one of the sides.
Conulariids range from the Ediacaran (about 550 million years ago) to the Late Triassic (about 200 million years ago). They survived three major extinctions (end-Ordovician, Late Devonian, end-Permian), which is remarkable considering the company they kept in their shallow marine environments suffered greatly. Why they went extinct in the Triassic is a mystery.

The primary oddity about conulariids is their four-fold symmetry. They had four flat sides that came together something like an inverted and extended pyramid. The wide end was opened like an aperture, although sometimes closed by four flaps. Preservation of some soft tissues shows that tentacles extended from this opening. Their exoskeleton was made of a leathery periderm with phosphatic strengthening rods rather than the typical calcite or aragonite. (Some even preserve a kind of pearl in their interiors.) Conulariids may have spent at least part of their life cycle attached to a substrate as shown below, and maybe also later as free-swimming jellyfish-like forms.

It is the four-fold symmetry and preservation of tentacles that most paleontologists see as supporting the case for a scyphozoan placement of the conulariids. Debates continue, though, with some seeing them as belonging to a separate phylum unrelated to any cnidarians. This is what’s fun about extinct and unusual animals — so much room for speculative conversations!

[Thanks to Consuelo Sendino of The Natural History Museum (London) for correcting the age range of these fascinating organisms.]

References:

Hughes, N.C., Gunderson, G.D. and Weedon, M.J. 2000. Late Cambrian conulariids from Wisconsin and Minnesota. Journal of Paleontology 74: 828-838.

Van Iten, H. 1991. Evolutionary affinities of conulariids, p. 145-155; in Simonetta, A.M. and Conway Morris, S. (eds.). The Early Evolution of Metazoa and the Significance of Problematic Taxa. Cambridge University Press, Cambridge.

[Modified from an original post on July 31, 2011]

Wooster’s Fossil of the Week: Spiriferinid brachiopod from the Lower Carboniferous of Ohio

October 14th, 2016

syringothyris-texta-hall-1857-anterior-585Sometimes I choose a Fossil of the Week from our Invertebrate Paleontology teaching collection because students have responded to it in some way. This week’s fossil brachiopod has confused my students a bit because it is an internal mold (unusual for brachiopods in our experience) and a member of the Order Spiriferinida rather than the Order Spiriferida. (Catch that? The difference is in two letters.) It is Syringothyris texta (Hall 1857) from a local exposure of the Logan Formation (Lower Carboniferous). Above is a view of the anterior showing the medial fold and sulcus (like an anticline). This, by the way, is the largest brachiopod in our collection.

syringothyris-texta-hall-1857-posterior-585Syringothyris Winchell, 1863, is a genus within the order Spiriferinida, as noted before. This order was erected in 1994, pulling it from the more familiar Order Spiriferida. In this preservation, the spiriferinids are distinguished by a high cardinal area in the posterior (shown above). Not much higher than the spiriferids, truth be told.

syringothyris-texta-hall-1857-dorsal-585This is a view of the dorsal valve side of this internal mold. Note the absence of ribs (plicae) on the fold in the middle.

a_winchellThe geologist and paleontologist Alexander Winchell (1824-1891) named and described the genus Syringothyris. We met Winchell before in this blog as he described many common fossil taxa in the Midwest. He was born in upstate New York, a seventh-generation New Englander. In 1847 he was graduated from Wesleyan University in Connecticut. He had a varied and peripatetic career, spending most of his time as a teacher of science. He first taught in New Jersey, New York and Alabama, staying a short time in each place. He founded the Mesopotamia Female Seminary in Eutaw, Alabama, and became president (briefly) of Masonic University in Selma. In 1854, Winchell was appointed professor of physics and civil engineering at the University of Michigan, a position that soon became geology and paleontology. Five years later he became the state geologist of Michigan, a job characterized by an apparently difficult relationship with his superiors. In 1872 he left Michigan to be chancellor of Syracuse University, lasting only two years. Next he was a professor of geology and zoology at Vanderbilt University, a position he was forced to resign from in 1878 due to his unbiblical views of evolution. Winchell then returned to the University of Michigan, again as a professor of geology and paleontology. There is where he died.

Winchell’s views on evolution were complicated by his religiosity, and his religious life was made difficult by evolution. He developed a kind of transcendental Darwinism in which selection was reduced to inflexible laws from the Creator, a view we would today call Intelligent Design. He then confused it all by writing a popular book called Preadamites, published in 1880. The darker races, he said, lived in Europe and Asia before Adam. Adam and the subsequent “Noachites” were derived from Negroes, according to Winchell, advancing steadily in intellectual development and whiteness while the black race and other Preadamites were left behind. This work is profoundly racist and pseudoscientific, despite the Darwinian gloss he attempted to paint over it.

a-screen-shot-2016-10-10-at-8-49-42-pmb-screen-shot-2016-10-10-at-8-57-04-pmFrontispiece of Winchell (1880).

References:

Bork, K.B. and Malcuit, R.J. 1979. Paleoenvironments of the Cuyahoga and Logan Formations (Mississippian) of central Ohio. Geological Society of America Bulletin 90: 89–113.

Vörös, A., Kocsis, Á.T. and Pálfy, J. 2016. Demise of the last two spire-bearing brachiopod orders (Spiriferinida and Athyridida) at the Toarcian (Early Jurassic) extinction event. Palaeogeography, Palaeoclimatology, Palaeoecology 457: 233-241.

Winchell, A. 1863. Descriptions of FOSSILS from the Yellow Sandstones lying beneath the “Burlington Limestone,” at Burlington, Iowa. Academy of Natural Sciences of Philadelphia, Proceedings, Ser. 2, vol. 7: 2-25.

Winchell, A. 1880. Preadamites; or a demonstration of the existence of men before Adam. Chicago, S.C. Griggs and Company; 500 p.

Wooster’s Fossils of the Week: Tiny athyridide brachiopods from the Lower Carboniferous of the West Midlands of England

September 9th, 2016

1 Hustedia radialis 585These little brachiopods were also in the recent gift package from Clive Champion, our English brachiopod expert and friend. They tested my photographic skills, being too large for our photomicroscope and at the limit of resolution for my camera with its extension tubes. They are the athyridide Hustedia radialis (Phillips, 1836) from the Chadian-Arundian Limestone (Viséan, Lower Carboniferous) exposed near Wetton, Staffordshire, England. Brachiopods of this size are often referred to as “micromorph“, with some debate as to whether they are dwarfed adults or juveniles. With this fauna the consensus is the former.

Athyridide brachiopods are “spire-bearing”, meaning they have complexly-spiraled lophophore supports (brachidia) inside their shells. The lophophore is a tentacular device that creates a water current and traps organic bits from it for nutrition. These tiny critters thus had surprisingly elaborate feeding systems. The first paleontologist to grind through these minuscule shells to sort out the twists and turns of their microscopic brachidia is a hero of science.
2 John Phillips (1800-1874)Hustedia radialis was named in 1836 by one of the most important English geologists of the 19th Century, John Phillips (1800-1874). He originally called it Terebratula radialis, a common genus name applied at the time to biconvex brachiopods with pedicle openings (the hole for the attaching stalk visible at the pointy end of the shell).
3 Geology of YorkshireHe named it in the second volume of his Geology of Yorkshire series.
4 Brachs PhillipsSee if you can find the two figures of Terebratula radialis in Plate XII of the book. (Hint: small, triangular and ribbed!)

John Phillips was born in Wiltshire in 1800. His mother was a sister of the famous William “Strata” Smith, another founding father of modern geology. Phillips father and mother died when he was only seven years old, so William Smith took over raising him, despite his genteel poverty. Phillips traveled with Smith throughout England in the course of making Smith’s famous 1815 map. Phillips had a spotty formal education, but was clearly a quick study. By 1824 he was organizing museum fossil collections in Yorkshire, and in 1826 he became keeper of the Yorkshire natural history museum. Phillips then advanced very quickly, helping organize the new British Association for the Advancement of Science, becoming a professor of geology at King’s College London, and then at the age of 34 he was elected a Fellow of the Royal Society. All the while he kept up a prodigious rate of publication. The honors and positions continued for Phillips, with him eventually becoming a Reader of Geology at Oxford University. A remarkable career with such an unpromising start.
5 Phillips 1841 160Phillips published the first geological time scale in 1841, inventing the term “Mesozoic” in the process. The above clip is from Phillips (1841, p. 160).
6 Phillips 1860 time scaleHere is his 1860 version of the geological time scale (Phillips, 1860, p. 51).

After an April 1874 dinner at All Souls College in Oxford, John Phillips fell down a flight of stone steps, dying the next day. No doubt but for this fall he would have continued producing geological work into the next decade.

References:

Brunton, C.H.C. 1984. Silicified brachiopods from the Viséan of County Fermanagh, Ireland (III). Rhynchonellids, spiriferids and terebratulids. Bulletin of the British Museum (Natural History), Geology 38: 27–130.

Brunton, C.H.C. and Champion, C. 1974. A Lower Carboniferous brachiopod fauna from the Manifold Valley, Staffordshire. Palaeontology 17: 811–840.

Mottequin, B., Sevastopulo, G. and Simon, E. 2015. Micromorph brachiopods from the late Asbian (Mississippian, Viséan) from northwest Ireland (Gleniff, County Sligo). Bulletin of Geosciences 90: 307-330.

Phillips, J. 1836. Illustrations of the geology of Yorkshire, Part 2. The mountain limestone district. 253 pp. John Murray, London.

Phillips, J. 1841. Figures and Descriptions of the Palaeozoic Fossils of Cornwall, Devon and West Somerset. 231 pp. Longman, Brown, Green and Longmans, London.

Phillips, J. 1860. Life on the earth: its origin and succession. 224 pp. Macmillan and Company, London.

7 Gould bookplateFun feature of that last reference: Google Books scanned a personal copy of Stephen Jay Gould, a famous American paleontologist and evolutionary theorist.

8 Darwin quoteOn one of the front pages is this penciled note: ‘Unreadable, dull’ – Charles Darwin to [unknown] 15/1/61. [UPDATE: See comment from Katherine Marenco below.]

A Wooster Geologist Visits Spangler Park

May 9th, 2016

Chloe1Editor’s note: The following entry was written by Chloe Wallace (’17), a student in this year’s Sedimentology & Stratigraphy course. One of our writing assignments was to write a blog post about our recent field trip to Spangler Park (also known as Wooster Memorial Park). I told the class that I would publish on this site the best entry, and Chloe won. It was a very close contest, though, with many other excellent entries. All the following words and images are Chloe’s.

Wooster, Ohio— On April 23, 2016, the Sedimentology and Stratigraphy class took a field trip to the local Wooster Memorial Park, also called Spangler Park. The goal was to study three separate outcrops, and then do a little exploring of our own.

The first stop was a short walk from the entrance to the park, specifically at 40.81475° North and 82.02383° West (above).

This outcrop contains rocks from the Logan Formation of the Lower Carboniferous. The rocks were non-laminated and of silt size, so it is made of siltstone. There are signs of a little bit of oxidation. There are also ripples present on some of the rocks, which is evidence of a shallow water environment. There were gray shale clasts within the siltstone, which were most likely deposited by storm events. The fact that some of the beds are thicker than others is more evidence of storm events because more sediment would have been deposited during storms and thinner beds would have built up during times of less activity. The bedding angles vary throughout the outcrop, also known as cross-stratification, which is more evidence that ripples and dunes were present as part of a flow regime at the time of deposition.

Chloe2Burrow fossils, which are a form of trace fossil, were left behind by deposit feeding organisms on some of the rocks. This is more evidence of a shallow, marine environment. Based on all the sedimentary structures and characteristics found at this outcrop, these rocks were deposited on the shallow shelf, below the fair weather wave base and above the storm wave base.

The Logan Formation is made up of five members, but specifically the Byer member is likely exposed here. Layers of fine sandstone and siltstones with shale sometimes inter-bedded characterize the Byer member (Hunt, 2009). Although it isn’t present in the two photos above, another member is usually deposited right below the Byer Member. It is called the Berne Member and it is composed of molasse rock, which is a quartz-rich conglomerate formed when the eroded material from continental collisions gathers in a foreland basin. In this case it is eroded material from the continental collisions that built up the Appalachians. The eroded material was then deposited to the west in the foreland basin that covers Pennsylvania and Ohio.

The second outcrop we reached was at the bottom of a gorge, along Rathburn Run, specifically at 40.81784° N and 82.02946° W. The exposure was composed of laminated grey shale from the Cuyahoga Formation. It marked a formation boundary because Logan Formation sandstone lies directly above it. This means the grey shale is older than the Logan Formation. Similar to the Logan Formation, there are trace fossils of marine burrowing organisms within the shale.

Chloe3In the above picture you can see an East-West trending joint running through the center of the Cuyahoga Formation grey shale caused by tectonic faulting, which is a phenomenon unrelated to the sedimentary structures.

Chloe4Siderite deposits were also found in some sandstone at the Rathburn run outcrop, which form after deposition, a diagenetic property. Siderite forms in anoxic environments where iron is reduced and sulfur is present. The grey shale of the Cuyahoga Formation isn’t porous enough for siderite replacement to take place, but the sandstone is.

The third outcrop was father upstream along on a cut bank, located at 40.81903° N and 82.02953° W.

Chloe5This photo is taken from across Rathburn Run, from the point bar. This outcrop is much younger in age, from the last time Ohio was affected by glaciation. During the Last Glacial Maximum, specifically the Pleistocene, glacial debris flows deposited the bottom section of the outcrop. The sediment is characterized by a fining upwards sequence and has two scales of support. Some areas of the deposit are composed of large grains within a matrix-support due to debris flow. Other areas of the deposit are composed of sandy conglomerate rock that is grain supported. Overall the sediment is poorly sorted and contains glacial erratics within the sediment, including boulders made of gneiss, granite, and some sedimentary rocks.

A channel cut through the original glacial debris flow deposit and was eventually filled in by wind-blown silt, also known as loess. Loess is characteristically different from the glacial deposit at the bottom of the outcrop. Loess breaks in sheets, which causes it to have steep angles. Overall, the history of this outcrop is that approximately 15,000 years ago debris flow events deposited the glacial sediment at the bottom of the outcrop, then a channel cut into the deposit and that channel eventually filled with eolian (wind-blown) silt.

Chloe6After venturing a little on our own, a few other students and myself came across a fourth outcrop that was from the Logan Formation at an elevation above both the Cuyahoga Formation shales and the glacial deposits. There is more evidence of jointing and cross-stratification that can be seen in the picture.

We saw two separate formations from the Lower Carboniferous during the field trip. We also were able to see another type of sedimentary deposit that was glacial and eolian in origin. Spangler Park displays and exposes a variety of sedimentary structures and sedimentary characteristics. The park can be characterized as displaying a coarsening upwards sequence with the Cuyahoga shale at the bottom, followed by the coarser siltstone and sandstone of the Logan Formation. This kind of coarsening upwards is usually evidence of either regression or progradation.

Both the Logan and Cuyahoga Formations are representative of shallow marine environments, as was seen in the evidence found at Spangler. Further research shows that the Cuyahoga Formation was deposited as part of a marine environment where the shoreline was prograding during the Kinderhookian and possibly very early Osagean (Bork and Malcuit, 1979; Matchen and Kammer, 2006). The Logan Formation followed and was deposited within a marine proximal deltaic environment during the Osagean (Hunt, 2009; Matchen and Kammer, 2006). This explains the coarsening upwards sequence and the marine sedimentary structures and fossils seen throughout the field trip.

References:

Bork, K.B., and Malcuit, R., 1979, Paleoenvironments of the Cuyahoga and Logan Formations (Mississippian) of central Ohio: Geological Society of America Bulletin II, v. 90, p. 1782-1838.

Hunt, H., 2009, Paleocommunities and Paleoenvironments of the Logan Formation (Mississippian, Osagean) of northeastern Ohio [Undergraduate thesis]: Wooster, The College of Wooster, 50 p.

Matchen, D.L., and Kammer, T.W., 2006, Incised valley fill interpretation for Mississippian Black Hand Sandstone, Appalachian Basin, USA: Implications for glacial eustasy at Kinderhookian-Osagean (Tn2-Tn3) boundary: Sedimentary Geology, v. 191, 89-113.

Sedimentology & Stratigraphy class in Wooster Memorial Park. Watch this space!

April 23rd, 2016

1 Glacial 042316This morning Wooster’s Sedimentology & Stratigraphy class visited Wooster Memorial (“Spangler”) Park for some field experience. A few of the students are shown above exploring a magnificent glacial deposit. I never did get a photo with all 21 students in it.

2 Logan Rathburn RunThe students are each writing a blog entry about the geology of this park as a writing assignment. You can see the instructions and additional images on our course page. The best entry will soon be posted in this blog under the student’s name. Above is a nice stream-side outcrop of the Logan Formation (Lower Carboniferous).

3 Trillium trail 042316It was a chilly but mercifully dry day for us. Classic early spring foliage for northeastern Ohio. [Dr. Lyn Loveless, our expert botanist, comes through in the comments: “Classic Spring Foliage – mostly (it seems from this scale) Dutchman’s Breeches, Dicentra cucullaria.  One stray Trillium.  Ah, Spring in Ohio!”]

4 Trillium grandiflorum 042316 585The most noteworthy flower this week is Trillium grandiflorum, a beautiful three-petaled white flower with six stamens.

5 Purple flower 042316This purple flower is unknown to me so far. I hope a kind expert adds its name in the comments![Lyn Loveless again is the kind commenter: “Phlox divaricata – Wild blue phlox.”]

 

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