Wooster’s Fossil of the Week: A crinoid-rich Lower Carboniferous siderite concretion (part I)

January 5th, 2014

Cobble Top 121413Last year Wooster emeritus geology professor Sam Root generously donated the above pictured siderite concretion to our paleontology collections. He had received it from a friend who didn’t know where it came from originally so we have no location. The fossils in it, though, show it is Lower Carboniferous in age and could well be from local outcrops of the Cuyahoga Formation. Sam knew this is a cool specimen so he wanted to see what we could make of it.

In the top view we can see crinoid stems running transversely across the surface. Remarkably, two crinoid calices (the arm-bearing crown of the crinoid at the top of the stem) are visible. The larger one is in the lower left. You can see the top of the stem to the farthest left, and then the calyx and attached arms to the right. The second calyx is in the upper right with the arms extending down and towards us. Finding one crinoid calyx with the delicate arms still attached is impressive; finding two in the same slab is a real treat.
Siderite Concretion Carboniferous 585Above is the other side of the concretion. Again a crinoid stem can be seen transverse across the surface. This stem is different from those on the other side, though. It does not have external sculpture, and it is separated into distinct pluricolumnals as if someone sawed through it at regular intervals.
Cobble closer 121413A closer view of the above shows yet another crinoid calyx, this one almost entirely buried in the rock with the arms extending to the surface. The arms have smaller sub-arms (pinnules) still attached. Amazing.

The concretion is made of the mineral siderite (an iron carbonate) that precipitated in fine-grained sediments around the fossils after they were buried. This usually takes place under subsurface anoxic and slightly acidic conditions. The crinoids with all their small and easily-disarticulated parts were buried quickly on the ancient seafloor, probably by a storm-induced pulse of silts and clays. The decay of their soft parts produced hydrogen sulfide gas ad carbon dioxide, triggering the geochemistry that caused the precipitation of siderite around them. The hard concretion that resulted was likely in a matrix of soft shale. The strength of the siderite kept the fossils from being crushed by the weight of sediment above. At some point many millions of years later, the shale eroded away and the concretion was freed to be picked up by some lucky person.

The crinoid stem that is divided into regular increments is interesting on its own. These segments with multiple columnals (the poker chip-like individual elements) are called pluricolumnals. They likely broke at pre-set weaknesses in the connective tissue of the living crinoid, something we see in their living descendants. This may have allowed them to break off their stems (autotomize) when in danger so that the calyx and remaining stem could float away for re-establishment elsewhere.

This concretion is so interesting that I (forgive me, Sam) could not resist cutting it open to see what is inside. The inner view is even more fascinating and will be revealed next week in part II of this story. As a teaser, it involves four minerals and a surprising mollusk!

References:

Baumiller, T.K. and Ausich, W.I. 1992. The broken-stick model as a null hypothesis for crinoid stalk taphonomy and as a guide to the distribution of connective tissue in fossils. Paleobiology 18: 288-298.

Gautier, D.L. 1982. Siderite concretions; indicators of early diagenesis in the Gammon Shale (Cretaceous). Journal of Sedimentary Research 52: 859-871.

Wooster’s Fossil of the Week: Echinoid fragments from the Upper Carboniferous of southern Nevada

December 8th, 2013

 

Bird Spring Echinoid Carboniferous KC33 585This rock has been in my Invertebrate Paleontology course teaching collection since I arrived in Wooster. I collected it way back when I was doing my fieldwork for my dissertation on the biostratigraphy and paleoecology of the Bird Spring Formation (Carboniferous-Permian). This specimen comes from Kyle Canyon in the Spring Mountains west of Las Vegas, Nevada. It is from the Upper Carboniferous part of the Bird Spring. It is up this week in honor of Jeff Thompson, a new graduate student at the University of Southern California beginning his thesis work on Paleozoic echinoids.

These are spines and test plates from the echinoid Archaeocidaris M’Coy, 1844. There are many far more attractive specimens known of Archaeocidaris, so consider this a more average view of what you’re likely to find in the fossil record. The test plates are polygonal and the spines have characteristic outward-directed thorns on them. This particular specimen was disarticulated after death in a shallow, possibly lagoonal environment.
M'CoyArchaeocidaris was named by Sir Frederick M’Coy, an Irish paleontologist. (You may have seen his name as McCoy or MacCoy, but he signed with the more natively Irish M’Coy.) M’Coy was born in 1817 or 1823 (I’m shocked that there is such a discrepancy in the records) in Dublin (maybe). His father was a physician and a professor at Queen’s College, Galway. M’Coy was apparently an early starter, giving his first paper in 1838 on bird functional morphology and classification. (He was either 15 or 21.) His work history is a bit spotty. In 1841 he became Curator of the Geological Society of Dublin, but was soon replaced. In 1845 he joined the new Geological Survey of Ireland hoping to be a laboratory paleontologist. He ended up doing fieldwork but was rather bad at it, resigning from that job. Off to Cambridge he went to assist Adam Sedgwick in describing fossils. He was at last doing something in which he excelled, resulting in important publications. In 1849 M’Coy was appointed Chair of Geology and Mineralogy at Queen’s College, Belfast. His last career move was a big one: he left Ireland for Australia in 1854 to become one of the first four professors of the new University of Melbourne and director of the National Museum of Victoria (now Museum Victoria). M’Coy was very successful in these roles, although I must note that he was an advocate of importing English rabbits into Australia (you know the result) and he appeared to be a bit of an anti-Darwinist. He died in Melbourne in 1899. (Thank you to my friend Patrick Wyse Jackson for these details on M’Coy.)
Echinocrinus urii pl XXVII 1 M'Coy 1844The above is a figure in M’Coy’s 1844 work of the echinoid Echinocrinus urii (M’Coy, 1844, pl. XXVII, figure 1). There is a long story as to how this E. urii became the type species of Archaeocidaris. Andrew Smith sums it as:

Cidaris urii Fleming, 1828, p. 478, by subsequent designation of Bather 1907, p. 453. Generic name Archaeocidaris validated in Opinion 370 under plenary powers, by suppression under same powers of generic name Echinocrinus Agassiz, 1841. Opinions of the International Commission of Zoological Nomenclature 1955, 11, 301-320.

In any case, you can see how closely this illustration of an Irish fossil resembles our fossiliferous slab from the Spring Mountains. Ireland is far from Nevada now, but in the Carboniferous they were considerably closer.

References:

M’Coy, F. 1844. A synopsis of the characters of the Carboniferous limestone fossils of Ireland. Dublin, Printed at the University Press by M.H. Gill.

Rushton, A. 1979. The real M’Coy. Lethaia 12: 226.

Wilson, M.A. 1985. Conodont biostratigraphy and paleoenvironments at the Mississippian-Pennsylvanian boundary (Carboniferous: Namurian) in the Spring Mountains of southern Nevada. Newsletters on Stratigraphy 14: 69-80.

Wyse Jackson, P.N. and Monaghan, N.T. 1994. Frederick M’Coy: an eminent Victorian palaeontologist and his synopses of Irish palaeontology of 1844 and 1846. Geology Today 10: 231-234.

Wooster’s Fossil of the Week: A crinoid calyx from the Lower Carboniferous of Iowa

November 24th, 2013

Macrocrinus verneuilianus (Shumard, 1855) 585In honor of Echinoderm Week for my Invertebrate Paleontology course, we have a beautiful crinoid calyx (or crown, or just “head”) on a slab from the Burlington Limestone (Lower Carboniferous, Osagean) found near Burlington, Iowa. I inherited this fossil when I arrived at Wooster, so I have no idea who collected it or when. The handwritten number is similar to those on many of our 19th century specimens. The sharp features of the specimen have been a bit dulled by a preparation technique that probably involved abrasives.

The crinoid is Macrocrinus verneuilianus (Shumard, 1855) of the Order Monobathrida. It is unusual in that it is preserved with its filter-feeding arms intact, along with a magnificent anal tube (see closer view below).
Macrocrinus anal chimney 585The anal tube, sometimes called an anal chimney, is just what you guessed it would be — an anus at the end of a long pipe of calcitic plates. Its primary purpose was all about hygiene. The tube allowed waste products to be whisked away far from the mouth of the crinoid, which was at the base of the arms. Some researchers suggest that the long tube served another function as well: it may have helped stabilize and direct the filter-feeding fan of outstretched arms in a stiff current, something like the tail of an airplane or a panel on a weather vane.

Macrocrinus verneuilianus (Shumard, 1855) diagramFigure of Macrocrinus verneuilianus (9) from “Paleontology of Missouri” (1884) by Charles Rollin Keyes. That long anal tube is not exaggerated!
Shumard585Benjamin Franklin Shumard (1820-1869) named Macrocrinus verneuilianus in 1855. As you might have deduced from his name, Shumard was a Pennsylvanian, having been born in Lancaster. He received his bachelor’s degree from Miami University in Oxford, Ohio, and then later earned an MD in Louisville, Kentucky, in 1843. As a young doctor in Kentucky, he began to collect fossils as a hobby. After just three years of medicine, he gave it up to pursue a career as a geologist. (Those Kentucky fossils must have been particularly fine!) By 1848 he was on geological surveys for Minnesota, Wisconsin and Iowa, and in 1850 he went on a geological survey expedition to Oregon. (Imagine that trip in 1850.) In 1853 he became the paleontologist in the Missouri Geological Survey. In 1858 he left Missouri to begin the first Geological Survey in Texas. The Civil War must have caused him considerable pain, since he was a Pennsylvanian in Texas. He moved to St. Louis and renewed his medical career in 1861. In 1869, he decided to move south to New Orleans for health reasons. The steamship he took burned to the waterline one evening north of Vicksburg. He was safely rescued, but contracted pneumonia in the process. He returned quickly to St. Louis and there died at 49 years of age. At the time of his death Shumard was president of the St. Louis Academy of Science and a member of the Geological Societies of London, France, and Vienna, and he was also a member of the academies of science in Philadelphia, Cincinnati, and New Orleans. No doubt we would have had much more scientific accomplishment from this young paleontologist had he lived longer.

References:

Ausich, W.I. 1999. Lower Mississippian Burlington Limestone along the Mississippi River Valley in Iowa, Illinois, and Missouri, USA, p. 139-144. In: H. Hess, W.I. Ausich, C.E. Brett and M.J. Simms (eds.), Fossil Crinoids, Cambridge University Press.

Ausich, W.I. and Kammer, T.W. 2010. Generic concepts in the Batocrinidae Wachsmuth and Springer, 1881 (Class Crinoidea). Journal of Paleontology 84: 32-50.

Lane, N.G. 1963. Two new Mississippian camerate (Batocrinidae) crinoid genera. Journal of Paleontology 37: 691-702.

Shumard, B.F. 1855. Description of new species of organic remains. Missouri Geological Survey 2:185–208.

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.

Sed/Strat goes local with its field trip: the Meadville Shale and the Logan Formation (Lower Carboniferous)

April 27th, 2013

MeadvilleB042713WOOSTER, OHIO–The traditional spring field trip in the Sedimentology & Stratigraphy course at Wooster is taken several hours south, usually in Jackson County or, as last year, in a soggy quarry outside of Dayton. This time, though, we stayed nearby, measuring and describing the local bedrock: the Meadville Shale Member and the Logan Formation, both in the Lower Carboniferous. We had a spectacular day with the best weather Ohio can offer.

Our first location, shown above, was in Lodi Community Park about 20 miles north of Wooster. A tributary of the Black River (the East Fork Black River) flows through a small valley, exposing the Meadville Shale in its steep sides. The Meadville is a member of the Cuyahoga Formation and is late Kinderhookian in age. The students above are beginning to measure the unit with their Jacob’s staffs.

MeadvilleA042713Candy Thornton and William Harrison are here at the exposed base of the Meadville. They’re taking a break from geology to examine a salamander they found on this fine spring morning.

Spiriferid042713 The Meadville is in part very fossiliferous. We found crinoids, bryozoans, bivalves and brachiopods like this nice spiriferid above.

FluteMarks042713 An interesting feature on the soles of some thin siltstones are these long, parallel grooves called flute marks. They were made when shells were dragged across a muddy substrate, leaving scour marks. We think they represent the basal unit of thin turbidites formed by sediment slurries that flowed across the seafloor.

SarahF042713Sarah Frederick climbed high on the outcrop with a measuring staff to describe the transition from a silty shale to a very fine sandstone.

PicnicTable042713Here a group of Wooster geologists compares notes as they construct their stratigraphic columns. Yes, this sunlight felt very good to us.

Logan042713Our afternoon stop was in southeastern Wooster along the onramp from north Route 83 to east Route 30. The Logan Formation exposed here is a Lower Carboniferous (early Osagean) very fine sandstone and conglomerate. This site is near what was once known as “Little Arizona” to older Wooster geologists. That exposure was mostly removed when this new onramp was constructed.

Conglomerate042713The base of the Logan has an extensive conglomerate sometimes referred to as the Berne Member. As you can see, it mostly consists of rounded quartz and chert pebbles, making it a very mature sediment.

Dewatering042713One of the distinctive features of this Logan outcrop are these large dewatering structures. These form when a water-rich slurry of sediment is forced upwards through the sediment above. Vertical channels are made between the rounded bases of sandstone bodies. One interpretation of these structures is that they were produced an earthquake shaking the water-saturated sediment. If this was the case, we would call these seismites.

LoganGroup042713Here a happy group of geologists is returning to the vans with various fossil and rock specimens. Now it’s time to write the reports!

 

 

Wooster’s Fossil of the Week: A camerate crinoid from the Lower Carboniferous of north-central Ohio

April 7th, 2013

Cusacrinus_daphne033013Visitors often bring rocks and fossils to the Geology Department for identification. We love to solve the puzzles (or at least make the attempt), and our new friends appreciate names and ages for their treasures. (Usually. We’ve disappointed more than a few finders of “meteorites”.) Last week a home-schooling group came in from nearby Ashland with a tray of stones they found in a stream bed eroding an exposure of the Lower Carboniferous (Kinderhookian) Meadville Shale Member of the Cuyahoga Formation. One of the objects was the spectacular fossil shown above.

This is a calyx and the attached arms (essentially the “head”) of a camerate crinoid known as Cusacrinus daphne (Hall, 1863). (Our friend Bill Ausich of Ohio State University provided the identification — these crinoids are his speciality.) It is preserved as an external mold, meaning that the actual skeleton was covered in sediment (or in this case a concretion) and then dissolved away, leaving a cavity showing a mold of its exterior details. It is a rare fossil to find in our part of the world.

CrinoidCalyx033013Above is a close-up of the calyx of Cusacrinus daphne (Hall, 1863). Note the radiating ridges on the exteriors of each thecal plate. They are characteristic of this species.

CrinoidArms033013These are some of the arms of the crinoid. They are complex because each arm is lined with tiny branches called pinnules, making feather-like extensions for filter-feeding.

Thank you to our new Ashland friends for sharing such a beauty with us!

References:

Ausich, W.I. and Roeser, E.W. 2012. Camerate and disparid crinoids from the Late Kinderhookian Meadville Shale, Cuyahoga Formation of Ohio. Journal of Paleontology 86: 488-507.

Kammer, T.W. and Roeser, E.W. 2012. Cladid crinoids from the Late Kinderhookian Meadville Shale, Cuyahoga Formation of Ohio. Journal of Paleontology 86: 470-487.

The field trip scout

March 30th, 2013

MeadvilleLodi033013WOOSTER, OHIO–One of the early spring pleasures of a geologist in the Upper Midwest is finally getting outside and scouting the field trips for the semester. Today we had bright sun and temperatures in the 50s (I know — I’m settling) so I went out to plan the late April field trip for my sedimentology and stratigraphy class. The sites I’ve been using in the last few years have become too overgrown, so it is time to find new projects in new places. Since the delightfully underbrush-free Mojave Desert is too far away, I’m looking at places in northeastern Ohio. It was a fun day.

Above is an outcrop of the Meadville Shale Member of the Cuyahoga Formation (Lower Carboniferous, late Kinderhookian) exposed in the Lodi Community Park about 20 miles north of Wooster. A tributary of the Black River (the East Fork Black River) flows through a small valley, exposing the shale in its cutbanks. I’m a bit partial to this location because from here a fellow Wooster student found a trilobite that became the basis of my first scientific publication. The unit here is moderately fossiliferous and contains numerous rock types besides shale. It will make a fine place for students to measure and describe stratigraphic sections next month. It certainly was a beautiful place to spend a sunny Saturday morning.

TurkeyVulture033013There were many turkey vultures (Cathartes aura) perched in the still-leafless trees in northern Wayne and southern Medina Counties. Here’s one keeping an eye on me. Turkey vultures are a sign in Ohio that spring really is coming (even if it is supposed to snow tomorrow morning!).

Wooster’s Fossil of the Week: A twisty trace fossil (Lower Carboniferous of northern Kentucky)

January 27th, 2013

My Invertebrate Paleontology students know this as Specimen #8 in the trace fossil exercises section: “the big swirly thing”. It is a representative of the ichnogenus Zoophycos Massalongo, 1855. This trace is well known to paleontologists and sedimentologists alike — it is found throughout the rock record from the Lower Cambrian to modern marine deposits. It has a variable form but is generally a set of closely-overlapping burrow systems that produce a horizontal to oblique set of spiraling lobes. It was produced by some worm-shaped organism plunging into the sediments in a repetitive way, gradually making larger and larger downward-directed swirls.

Zoophycos is a useful indicator of ancient depositional conditions. It give its name, in fact, to an ichnofacies — a set of fossils and sediments characterize of a particular environment. In the Paleozoic it is found in shallow water and slope environments; from the Mesozoic on it is known almost entirely from deep-sea sediments. Our specimen is from the Borden Formation and was found amidst turbidite deposits, so it is probably from an ancient slope system.

There has been much debate about the behavior and objectives of the organisms who made Zoophycos. The traditional view is that it was formed by an animal mining the sediment for food particles, a life mode called deposit-feeding. Some workers, though, have suggested it could have been a food cache, a sewage system, and even an agricultural garden of sorts to raise fungi for food. I think in the end the simplest explanatory model is deposit-feeding, although with such a long time range, a variety of behaviors likely produced this trace.

Zoophycos was named in 1855 by the Italian paleobotanist Abramo Bartolommeo Massalongo (1824-1860). Massalongo was a member of the faculty of medicine at the University of Padua, chairing their botany department. (Medicine had broad scope in those days!) Why was he studying this trace fossil? Like most of the early scientists who noticed trace fossils, he thought it was some kind of fossil plant.
Zoophycos villae (Massalongo, 1855, plate 2)

References:

Bromley, R.G. 1991. Zoophycos: strip mine, refuse dump, cache or sewage farm? Lethaia 24: 460-462.

Ekdale, A.A. and Lewis, D.W. 1991. The New Zealand Zoophycos revisited: morphology, ethology and paleoecology. Ichnos 1: 183-194.

Löwemark, L. 2011. Ethological analysis of the trace fossil Zoophycos: Hints from the Arctic Ocean. Lethaia 45: 290–298.

Massalongo, A. 1855. Zoophycos, novum genus Plantarum fossilum, Typis Antonellianis, Veronae, p. 45-52.

Olivero, D. 2003. Early Jurassic to Late Cretaceous evolution of Zoophycos in the French Subalpine Basin (southeastern France). Palaeogeography, Palaeoclimatology, Palaeoecology 192: 59-78.

Osgood, R.G. and Szmuc, E.J. 1972. The trace fossil Zoophycos as an indicator of water depth. Bulletin of American Paleontology 62 (271): 5-22.

Sappenfield, A., Droser, M., Kennedy, M. and Mckenzie, R. 2012. The oldest Zoophycos and implications for Early Cambrian deposit feeding. Geological Magazine 149: 1118-1123.

Wooster’s Fossils of the Week: Beautiful molds on a concretion (Lower Carboniferous of Ohio)

September 30th, 2012

Kit Price (’13) was exploring a local creek on a Geomorphology course field trip north of Wooster led by Dr. Greg Wiles. Like the excellent paleontologist Kit is, her eyes continually searched the pebbles, cobbles, slabs and outcrops for that distinctive outline of something fossilian. This particular place has been in the blog before, so we know the stratigraphic and geological context of the rocks. Kit saw the curious golden brown, rounded rock above and immediately noted the presence of several fossils on its exterior. She collected it, cleaned it up, and the two of us examined the treasures.

Here is the key to what we found: A = trilobite pygidium external mold (more on this below); B = productid brachiopod dorsal valve internal mold; C = replaced bivalve shell fragment; D = productid brachiopod ventral valve external mold; E = nautiloid external mold. There are also external molds of twiggy bryozoans on the surface, but they are too small to distinguish in this view.

This rock is an ironstone concretion formed within the Meadville Member of the Cuyahoga Formation (Kinderhookian; Lower Carboniferous). It weathered out of the softer shale matrix and lay free on the creek bed. The original shells of the various fossils were dissolved away after burial, either being replaced with iron oxides (like the bivalve) or just remaining as open cavities (the molds). They represent a little survey of some of the animals that lived in this shallow, muddy seaway. Most of these fossils would have been lost to the dissolution, but the hard concretion preserved them.

The most interesting fossil here is the external mold of the trilobite pygidium (or tail piece). We don’t see these very often in Carboniferous and later rocks. The group is dwindling in advance of their final extinction at the end of the Permian period. I suspect this is the pygidium of Brachymetopus nodosus Wilson, 1979. I can only guess this, though, because only the cephalon (or head) of B. nodosus was described originally from the Meadville Member. This may be the long-missing pygidium of that species. It certainly has the little bumps that we would expect. (By the way, if you stare at the above image long enough, it appears in positive relief rather than the actual negative relief (or hole) that it is. It “pops out”, giving a view of what it may have looked like in life.)

Thanks, Kit, for such a nice view of a local Carboniferous community! It also brought back fond memories of my own local explorations as a Wooster student long, long ago.

References:

Corbett, R.G. and Manner, B.G. 1988. Geology and habitats of the Cuyahoga Valley National Recreation Area, Ohio. Ohio Journal of Science 88: 40-47.

Wilson, M.A. 1979. A new species of the trilobite Brachymetopus from the Cuyahoga Formation (Lower Mississippian) of northeastern Ohio. Journal of Paleontology 53: 221-223.

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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