Wooster’s Fossil of the Week: A scale tree root in its own soil (Upper Carboniferous of Ohio)

Mark Wilson April 15, 2012 1:48 am

Last week a local man, Larry Stauffer, brought in the above fossil for identification and then kindly donated it to the department. It is part of the root system of Lepidodendron, the “scale tree” of the Carboniferous Period. What is especially cool about it is that the rootlets, thin ribbon-like perpendicular extensions, are still attached. Usually they were lost quickly when the root was dislodged from its bed.

The well-preserved rootlets show that this bit of root is still in its original soil. Such a fossil soil is called a paleosol. These features are important in the rock record because they show ancient climate conditions, weathering profiles and sedimentation rates. Carboniferous paleosols like this are called seat earth.

The roots of Lepidodendron were given a separate generic name in 1822 by the French naturalist Alexandre Brongniart (1770-1847). He called them Stigmaria because of the regularly-spaced holes called stigmata. (You may know “stigmata” from an entirely different context!) The name was superseded by Lepidodendron once it was figured out how the roots, trunk, and leaves were connected.

Diagram of “Stigmaria ficoides”  from “Elements of Geology: The Student’s Series” by Charles Lyell (1871).

Brongniart is best known to me as one of the first biostratigraphers. He worked out the first divisions of the Tertiary Period (now known as the Paleogene and Neogene Periods) using fossils to mark time intervals. He also was the first to systematically study the trilobites at the other end of the geologic time scale. Brongniart did original geological mapping with the famous Georges Cuvier in the Paris region as well. He was a professor at the École de Mines and director of the Sèvres porcelain factories. I think he looks rather friendly in a Frenchy way.

References:

Brongniart, A. 1822. Sur la classification et la distribution des végétaux fossiles en général, et sur ceux des terrains de sédiment supérieur en particulier. Soc. Philom., Bull., pp. 25-28 and Mémoires Du Muséum d’Histoire Naturelle 8: 203–240, 297–348.

Frankenberg, J.M. and Eggert, D.A. 1969. Petrified Stigmaria from North America: Part I. Stigmaria ficoides, the underground portions of Lepidodendraceae. Palaeontographica 128B: 1–47.

Jennings, J.R. 1977. Stigmarian petrifications from the Pennsylvanian of Colorado. American Journal of Botany 64: 974-980.

Rothwell, G.W. 1984. The apex of Stigmaria (Lycopsida), rooting organ of Lepidodendrales. American Journal of Botany 71: 1031-1034.

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Sand and Gravel in the Holmesville Moraine

gwiles April 13, 2012 10:39 pm

The College of Wooster Geomorphology class set out to explore the Holmesville Moraine, a 20 minute drive south of Wooster straight down the Killbuck River Valley. It was a beautiful day, except for the rain. The first stop was Holmesville Sand and Gravel, a company which mines and sorts the deposit and sells it for various building and homeowner applications. We ended up classifying this as a Kame Moraine as most of the sediment is sand and gravel intermixed with diamict all piled up into a great cross valley ridge. This is likely the dam for Glacial Lake Killbuck, which was impounded to the north.

The Separator – This machine and associated conveyors sorts the gravel from the sand from the silt.

Sorted piles – note the varying angles of repose.

 

 

 

 

 

 

 

 

 

 

 

 

 

The dredge sucks sand from 70 feet down in this lake. It is then piped to the Separator.

 

Fine-grained sand and silt is returned to the lake – note the delta. A wave-dominated delta that is revealed with a modest drop in lake level.

Continue reading this post to see why the group is dumbfounded.

Ice-contact stratified drift – sediments range from diamicts to stratified sands and gravels. Many of the gravels are cemented. Note that the lower left is a bedrock contact. This is the guts of the kame moraine.

Cemented sand and gravel – note the evenly-space joints where the rivelets have excavated the materials – joints from unloading?

Cemented and partially stratified diamict – this unit is a major challenge to remove in mining.

Raindrop imprints on mudcracks.

Ditch draining the floor of former Glacial Lake Craigton – note the peaty sediments and the tiles. Note the meandering thalweg within the ditch.

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A Drool-Worthy College Museum

mpollock April 11, 2012 9:00 am

AMHERST, MA – Last weekend, some Wooster Geologists attended the Keck Symposium at Amherst College and were awed by their geology museum. The Beneski Museum of Natural History  is housed in a modern building and covers three floors, displaying over 1,700 specimens. The museum hosts the Hitchcock Ichnology collection, the world’s largest collection of dinosaur footprints. Other highlights include the wall of mammals, an impressive mineral collection, and exquisite table tops of polished stone. Here are a few photos that might just make your jaw drop.

A large mastodon and other mammals greet visitors as they enter the museum.

The Hitchcock Ichnology Collection is the largest collection of dinosaur footprints in the world.

Casts of dinosaur footprints featured on the Hitchcock Collection webpage.

Was the dinosaur running or walking to make these tracks?

A large mold.

The cast that fits into the mold above.

Fossilized mudcracks, viewed from below.

Fossilized raindrops.

The petrified trunk of an ancient tree.

Want to keep a geologist busy for hours? Give her a countertop that looks like this.

 

 

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Wooster’s Fossils of the Week: A calcareous sponge with a crinoid holdfast (Matmor Formation, Middle Jurassic, Israel)

Mark Wilson April 8, 2012 1:58 am

The Class Calcarea of the Phylum Porifera is a group of sponges characterized by spicular skeletons made of calcium carbonate (calcite in this case). The spicules (small elements of the skeleton) are often fused together, causing the sponges to look a bit like corals or bryozoans. They are among the most common fossils in the Matmor Formation (Middle Jurassic, Callovian) of southern Israel. Melissa Torma and I collected this particular fossil on our expedition last month. It is another indication that the Matmor Formation was deposited in very shallow waters.
This is the underside of the Matmor calcareous sponge. (I wish we had a name for it, but the taxonomy is in considerable flux right now.) You can see the way it grew radially around an encrusting center. In the lower right a circular oyster attachment is visible.
A close view of the top surface of the calcareous sponge showing radiating canals called astrorhizae. They were used to channel water currents for the sponge’s filter-feeding system.
This crinoid holdfast (the base of an attaching stem) locked onto the calcareous sponge after its death. We can tell this because it is bound to the spicular skeleton itself, which was only exposed after the sponge’s soft tissues rotted away. It is not possible to identify the crinoid, but it is likely in the genus Apiocrinites.
The Class Calcarea was named by James Scott Bowerbank in 1864. Bowerbank (1797-1877) was an English naturalist born in London. He helped run a distillery with his brother, making enough money to support his diverse interests in natural history. He collected many fossils in his life, specializing in the London Clay (Eocene). His various publications gained him membership in the Royal Society in 1842. His greatest work was probably a four-volume set titled “A Monograph of the British Spongidae”. (You can read at least part of this work online.) He was well known as a strong supporter of young scientists, opening his home and collections (and use of his valuable microscopes) to all those seriously interested in natural history. I like to think he would have been happy as a liberal arts geology professor!

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Wooster Geologists: Communicating New Knowledge

mpollock April 7, 2012 9:51 pm

AMHERST, MA – Congratulations to Wooster Geology Seniors Katharine and Andrew for their excellent presentations at today’s Keck Symposium! Andrew presented the results of his remote sensing investigation of channels on Ascraeus Mons on Mars. Andrew compared his channels to those on Pavonis Mons and in Hawaii. He characterized his channels as volcanic in origin based on their spatial distribution, surface stratigraphy, and geomorphological relationships.

Andrew poses by his poster during a rare quiet moment at the poster session.

Katharine presented her study of the Hrafnfjordur central volcano in the West Fjords of northwest Iceland. She found a complicated sequence of eruptive units that includes pyroclastic material, basalt, andesite, and dacite. Using geochemistry, Katharine determined that the units fall on different, genetically unrelated trends, suggesting that the Hrafnfjordur central volcano has a complex magmatic history.

Katharine enthusiastically explains her study to a thoughtful listener.

Overall, the Keck students are truly a motivated and talented bunch. It’s amazing to see what these students have accomplished over the course of a year. The symposium is not only a celebration of their achievements, it’s a powerful moment in which these students officially become part of the Keck alumni family.

The 2011-2012 Wooster Keck alumni.

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Field Trip Friday

mpollock April 6, 2012 9:20 pm

AMHERST, MA – If you were following our adventures last summer, you’ll remember that Wooster helped lead a 6-student Keck trip to the West Fjords in northwest Iceland. You may not know that we also had a Wooster presence on the Keck Mars project. Now, after nearly a year of hard work, all of the Keck students are coming together at the Keck Symposium to share their findings and celebrate their accomplishments. This year, we’re at Amherst College in Massachusetts. The symposium kicked off today with glorious weather and a local field trip featuring “The ABV’s of Valley Geology: Arkose, Bedrock, and Varves.”

Our first stop was in the Moretown Formation. These early Paleozoic rocks were originally deposited on the edge of the continent and were subsequently deformed during the Taconic and (perhaps) the Acadian Orogenies. The outcrop consisted of interbedded schist and quartzite that had been metamorphosed to upper greenschist – lower amphibolite facies. We observed tight folds that showed fantastic crenulation cleavage, which developed as a result of multiple folding events.

Side-view of the crenulation cleavage, almost looking down the cleavage crenulation hinge.

The light reflects off of the wavy surface of micaceous schist layers. The pen is nearly aligned with the cleavage crenulation hinge.

Garnet porphyroblasts in the Moretown Formation.

After a brief stop at the Yankee Candle Company (what’s not to like about hot coffee, clean restrooms, and plentiful scented candles?), we made our way to Mt. Sugarloaf. Here, we visited the type locality for the Triassic Sugarloaf Arkose, a feldspar-rich sandstone and matrix-supported conglomerate. The arkose was deposited in the Deerfield rift basin during the opening of the Atlantic. Abundant orthoclase suggests that the sediment was close to its source. Most of the sediment was deposited by debris flows, but there is some evidence for reworking by a braided stream system.

Conglomeratic section of the Sugarloaf arkose.

We hiked to the top of Mt. Sugarloaf for a scenic lunch stop, where we had a breathtaking view of the Mesozoic rift valley in which the Sugarloaf arkose was deposited.

View from the top of Mt. Sugarloaf.

After lunch, we traveled back to 15,000 years ago, when the rift valley was filled with proglacial lake Hitchcock. The lake was over 200 km long, stretching from upstate Vermont to central Connecticut. Seasonal layers of silt and clay were deposited on the lake bottom, forming varves. It’s the flat-lying varves that make the valley floor so flat. The annual layers were also critical in the development of the New England Varve Chronology, which suggest that the lake existed for over 4,000 years.

Lake Hitchcock varves.

Close-up view of the annual layers in the Lake Hitchcock varves.

Our last stop of the day was to see the trace fossil Eubrontes (aka dinosaur footprints). The three-toed tracks are subparallel. If the tracks are the same age, then they may have recorded a passing herd. If the tracks are on different bedding planes, then this area may have been on a migration route. The Amherst College Beneski Museum of Natural History hosts the largest collection of dinosaur tracks world, primarily collected by Edward Hitchcock (also of the proglacial lake, third president of Amherst College, 1845-1854).

Three-toed dinosaur footprint. Do you see it?

It was nice of the dinosaurs to outline their footprints in chalk to make it easier for us to see!

We finished the evening with a reception at the museum (a drool-worthy collection that will be the focus of a future post). After a quick pizza dinner, the Iceland group is meeting for the last time to work on tomorrow’s presentations. It’s a bittersweet meeting; it’s fun to bring everyone together to compare findings and pat ourselves on our backs for a job well done, but it’s a bit sad to know that our Keck experience is coming to an end.

The Iceland crew on the Keck Field Trip.

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Collaborative (and sticky) Inquiry in the Geology of Natural Hazards

mpollock April 3, 2012 7:45 pm

Wooster, OH – Today’s hazards class was devoted to lava viscosity. Viscosity plays an important role in controlling how volcanoes behave, from determining how quickly magma ascends to whether the eruption will be explosive or effusive. In Hazards, we’ve been discussing the factors that control lava viscosity, like silica content, volatiles, and temperature. Although we’d love to experiment on real lava, like the folks up at Syracuse University, we just don’t have the right set up. Instead, I borrowed Ben Edwards’ (Dickinson College) idea of using corn syrup. (I’m not the only one).

We simulated lavas of different viscosities by varying the temperature of the corn syrup and adding rice and sand. Then, we poured our “lava” down ramps and timed how fast they moved. We used their velocities to calculate viscosity and compared our results to real lava.

 

We also blew bubbles into our “lavas” to simulate volatiles.

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Wooster’s Fossil of the Week: A spiriferinid brachiopod (Logan Formation, Lower Carboniferous, Ohio)

Mark Wilson April 1, 2012 1:59 am

This brachiopod is one of the most common in the Logan Formation of Wooster, Ohio, so our students know it well from outcrops in Spangler Park and the occasional excavations in town. Four specimens of Syringothyris Winchell 1863 are visible in the slab above. The critter in the upper left is an earlier Fossil of the Week: the bivalve Aviculopecten subcardiformis. This suite of fossils is about 345 million years old (Osagean Series of the Lower Carboniferous).
We can’t identify the species of these Logan Formation brachiopods because the original shells dissolved away long ago. We are left with the sediment that filled the insides of the shells, producing what paleontologists call internal molds. Syringothyris belongs to the Order Spiriferinida, a group of elongate brachiopods that are punctate, meaning there are tiny holes penetrating their shells. Unfortunately this is one feature I can’t show you with internal molds!
Alexander Winchell (1824-1891) named and first described the genus Syringothyris. He was a geology professor at the University of Michigan for decades, specializing in Lower Carboniferous stratigraphy and paleontology. He was also the state geologist of Michigan. Winchell was one of the early American Darwinists, working hard to reconcile religion and science in the United States (with decidedly mixed results!).

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.

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.

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Wooster’s Fossils of the Week: Three cobble-dwelling oysters from the Upper Cretaceous of southern Israel

Mark Wilson March 25, 2012 1:45 am

These fossils of the week, three well-worn cemented oysters, are highlighted to celebrate the final acceptance this past week of a manuscript that describes their geological setting and significance: Wilson et al., 2012 (see reference below). They are attached to a cobble found at the base of the Menuha Formation (Santonian) near Makhtesh Ramon in southern Israel. These oysters represent the many sclerobionts that inhabited these cobbles. Here is the abstract of the paper:

Reworked concretions have been significant substrates for boring and encrusting organisms through the Phanerozoic. They provide large, relatively stable calcareous surfaces in systems where sedimentation is minimal. Diverse sclerobiont communities have inhabited reworked concretions since the Ordovician, so they have been important contributors to our understanding of the evolution of these ecological systems. Here we describe reworked concretions from southern Israel where they are critical for interpreting the stratigraphy and paleoenvironment of an Upper Cretaceous sedimentary sequence. These cobble-sized concretions (averaging roughly 1000 cubic centimeters) are found at the base of the Menuha Formation (Santonian to lower Campanian, Mount Scopus Group) unconformably above the top of the Zihor Formation (Turonian-Coniacian, Judea Group) exposed in the Ramon region of the Negev Highlands. The concretions are almost entirely composed of micritic limestone, and many are exhumed cemented burrow-fills apparently from 10-20 meters of upper Zihor Formation strata removed by erosion. There are also a few cobbles of dolomitic limestone and rare vertebrate bone. The cobbles are moderately to heavily bored by bivalves (producing Gastrochaenolites) and worms (forming Trypanites), and a few have cemented oysters. They are densely arrayed in a single layer, often touching each other or only a few centimeters apart. The sclerobionts associated with the cobbles, along with their hydrodynamic arrangement, strongly suggest that these cobbles accumulated in very shallow water above normal wave base. Most of them (77%) are encrusted on their top surfaces only, indicating that they were bored in place and not later delivered to a deeper environment by submarine currents. The rest of the Menuha Formation above is a chalk with relatively few macrofossils (primarily shark teeth and oysters) and a few trace fossils (Planolites and Thalassinoides are the most common). These reworked cobbles show that the initial deposits of the Menuha Formation accumulated in very shallow water. This has important implications for the development of the Syrian Arc structures in this region, especially the Ramon Monocline.

Two cobbles in their natural setting: embedded in the chalks at the base of the Menuha Formation.

The beautiful setting south of Makhtesh Ramon. The cliff is an exposure of the resistant Zihor Formation; above it are the white slopes of the far less resistant chalky Menuha Formation. The cobbles are found at the base of the Menuha.

A figure from the manuscript itself showing a cross-section of a cobble. The “T” indicates a Trypanites boring; the “G” shows a Gastrochaenolites boring.

Thank you again to Wooster alumni Micah Risacher and Andrew Retzler and current student Will Cary for helping us collect these specimens!

Reference:

Wilson, M.A., Zaton, M. and Avni, Y. 2012. Origin, paleoecology and stratigraphic significance of bored and encrusted concretions from the Upper Cretaceous (Santonian) of southern Israel. Palaeobiodiversity and Palaeoenvironments (in press).

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Glacial Features in Western Pennsylvania

mpollock March 22, 2012 7:15 pm

SLIPPERY ROCK, PA – I’ve just returned from the March meeting of the Pittsburgh Geological Society. If you’re in the region and you’re not a member, you really should think about joining. On the third Wednesday of each month, a robust group of faculty, students, and professionals gather for a social hour followed by a tasty meal and a geo-talk. I was honored to have the opportunity to speak about my passion for basalt geochemistry and was fully impressed by the friendly, engaged audience. The questions from the students, in particular, were clever and insightful. (Attention potential employers: the PGS is your regional source for the next crop of professional geologists).

The PGS also runs field trips, and my host, Dr. Patrick Burkhart, took me on a tour of glacial features near his home institution of Slippery Rock University.

A google map image of the glacial features near Slippery Rock, PA. The numbers correspond to the images below. (Imagery from DigitalGlobe, GeoEye, USGS, USDA Farm Service Agency).

We began our trip at the Jacksville Esker (also known locally as the West Liberty Hogback or Miller Esker), which may be the best-preserved esker in Pennsylvania (Fleeger et al., 2003). The >6 mile-long esker is an elongate, sinuous ridge of sand and gravel that was deposited about 23,000 years ago by meltwater in a subglacial tunnel (Fleeger and Lewis-Miller, 2009).

Photo #1: View of the elongated ridge formed by the Jacksville Esker.

Adjacent to Jacksville Esker is Tamarack Lake, an ecologically important wetland. We viewed Tamarack Lake from Swope Road, which cuts through the esker, and noticed a school of trout in the water near the road. I imagined that they were enjoying the warm spring day.

Photo #2: View of Tamarack Lake from Swope Road.

Photo #3: Trout enjoying the warm water at Tamarack Lake.

Jacksville Esker ends in the Kame Delta, which formed in a proglacial lake. Sediment in the delta is generally well-sorted, ranging from fine sand to cobbles, and is currently being mined by the Glacial Sand and Gravel Company (Fleeger and Lewis-Miller, 2009). We didn’t get to tour the quarry, but according to the field guide, mining has exposed  crossbeds, ripples, and multiple foreset beds that suggest that the delta was built by a series of depositional events (Fleeger and Lewis-Miller, 2009).

Photo #4: View of the relatively flat-topped Kame Delta. The gravel mining operation is located near the center of the photo.

We saw a few other things on the trip, but I think I’ll save those for another post.

References:

Fleeger, G. M., and Lewis-Miller, Jocelyn, 2009, Stop 7: Jacksville esker, delta, lake plain, and drainage diversion complex, in Harper, J. A., ed., History and geology of the oil regions of northwestern Pennsylvania. Guidebook, 74th Annual Field Conference of Pennsylvania Geologist, Titusville, PA. p. 146-159.

Fleeger, G. M., Bushnell, K. O., and Watson, D. W., 2003, Moraine and Mc- Connells Mill State Parks, Butler and Lawrence Counties—Glacial lakes and drainage changes: Pennsylvania Geological Survey, 4th ser., Park Guide 4, 12 p.

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