Milestones for two Wooster Geologists

There was some good news for the College of Wooster Earth Sciences faculty during the otherwise dreary Pandemic Year. The two cheerful Wooster geologists pictured above in the field (today!) reached important points in their professional lives.

Dr. Meagen Pollock was promoted to Full Professor this spring. This is a big deal in the academic world. The criteria are: “The College expects that faculty portfolios for promotion to Professor will demonstrate significant and sustained achievements in the areas of teaching, scholarship, research, and general value to the College after those that led to tenure and/or the rank of Associate Professor.” She’s going to have to update that faculty webpage!

This year Dr. Greg Wiles was elected a Fellow of the Geological Society of America. The requirements: “Society Fellowship is an honor bestowed on the best of our profession by election at the spring GSA Council meeting. GSA members are nominated by existing GSA Fellows in recognition of a sustained record of distinguished contributions to the geosciences and the Geological Society of America through such avenues as publications, applied research, teaching, administration of geological programs, contributing to the public awareness of geology, leadership of professional organizations, and taking on editorial, bibliographic, and library responsibilities.” Greg’s nomination was in two categories: “Publication of the results of geological research” and “Training of geologists”. No more than two categories could be selected — otherwise he would have more!

Congratulations to Meagen and Greg. They are heroes!

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Wooster Memorial Park – Now Part of the Old Growth Forest Network

On 20 April 2021 Wooster Memorial Park became part of the Old Growth Forest Network.  The founder and director, Joan Maloof, visited Wooster Memorial Park forest to officially induct the park into the Network. The Wooster Tree Ring Lab cored some of the white oaks in the park to determine their age and to see how they are responding to the increasingly wetter climate of Northeast Ohio. Nathan Kreuter (Biology) and Nick Wiesenberg (Earth Sciences Dept. Technician) found the oldest trees and helped work up the tree-ring data.

Joan Maloof with the largest hemlock in the park.

Nathan Kreuter cores one of the oldest oaks as part of his tutorial at the Wooster Tree Ring Lab.

The ring-widths of the Wooster Memorial Park chronology. There was a likely time of early logging in the park about 1815 and again in the 1920s
Tree ring widths are most sensitive to April-August total precipitation. The correlation between the ring-widths and precipitation changes over time with the strongest relationship r = 0.6 for the interval 1945-1975. After 1975 the correlation falls off possibly due to the increase in precipitation and loss of sensitivity at the site with the abundant moisture.

Friends of the trees and Friends of Wooster Memorial Park with Joan Maloof.

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Microbial Structures of the Middle Jurassic (Bajocian) Carmel Formation, Southwest Utah: William Santella’s Senior Independent Study thesis

Editor’s Note: Independent Study (IS) at The College of Wooster is a three-course series required of every student before graduation. Earth Sciences students typically begin in the second semester of their junior years with project identification, literature review, and a thesis essentially setting out the hypotheses and parameters of the work. Most students do fieldwork or lab work to collect data, and then spend their senior years finishing extensive Senior I.S. theses. This year we again had the COVID-19 pandemic to deal with, so our students have had few chances to publicly present their hard work and scientific ideas. Some, then, will be writing blog posts like this. The text and images here are from Will Santella (’21), who is a member of Team Utah 2020. The picture above shows an outcrop of the Lower Co-op Creek Limestone Member of the Carmel Formation at the Gunlock Reservoir, Gunlock, Utah. Now Will takes over —

The Lower Co-op Creek Limestone Member of the Carmel Formation (pictured above) is a sedimentary unit that formed at the southernmost tip of the epicontinental Sundance Seaway during the Bajocian stage of the Jurassic period. This thesis regards a small portion of the Lower Co-op Creek Limestone Member, located near the town of Gunlock, Utah. Among the plethora of invertebrate fossils lying in this unit are microbialites; ancient fossilized photosynthetic cyanobacterial mats which grew in the shallow-marine tidal zones characteristic of the Lower Co-op Creek Limestone Member.

These “microbialites” are classified in two groups; the laminated “stromatolite”, and the clotted “thrombolite”. The purpose of my thesis was to describe these extraordinary lifeforms by analyzing patterns in stromatolite laminae, and identifying unique thrombolite morphology.

Laterally-linked hemispheroid stromatolites at the Gunlock Reservoir locality.

Stromatolites are laminated benthic microbial deposits first identified by Ernst Kalkowsky in 1908. Formed by the lithification of sediment by photosynthetic cyanobacteria, stromatolites exhibit a variety of morphologies; those in the Carmel Formation are composed of finely layered continuous laminae. In an ideal environment, a stromatolite lamina is a perfect record of the sedimentary, biological, and atmospheric conditions at the time of lamination. I applied principals of cyclical harmonic analysis to laminae data in an attempt to map chronological changes in the morphology, composition, and habit of stromatolite laminae in the Lower Co-op Creek Limestone Member. This analysis was conducted by using a harmonic wavelength generator in RStudio to create models of cyclical changes in the recorded attributes of stromatolite laminae; the results of which were remarkable.

Laterally-linked hemispheroid stromatolite laminae under a petrographic microscope.

Chart describing trends in stromatolite lamination via a harmonic model (blue) and a linear regression model (red).

While I determined that there was no statistically significant change in stromatolite laminae over time, the morphology, composition, and habit of a stromatolite lamina was the direct result of the tidal stage under which it formed. “High tide laminae” were thicker, exhibited large diagenetic dolomite crystals, and contained a greater abundance of large quartz grains than their related “low tide laminae”, which were thin, and primarily composed of micritic sediment. This previously undescribed relationship between tidal stage and stromatolite lamination is key to understanding the growth patterns of these phenomenal organisms.

Thrombolite hand sample displaying unique clotted morphology.

Thrombolites are defined as cryptalgal structures related to stromatolites but lacking lamination and characterized by a macroscopic clotted fabric (Aitken, 1967). The term “macroscopic clotted fabric” refers to the matrix of internal mesoscopic structures that are composed of individual, distinct microbial colonies. These mesoscopic structures can be anywhere from less than a millimeter to several centimeters wide, and are separated by a dividing matrix of sediment, biological debris, or sparry carbonate (Kennard and James, 1986).

The thrombolites of the Lower Co-op Creek Limestone Member are unique- specifically, the small, lightly clotted morphology of these organisms is not described in literature regarding Bajocian paleontology. Additionally, thrombolite structures from the Carmel Formation do not match any of the widely used thrombolite morphology classifications described by Theisen and Sumner (2016). These thrombolites exhibit a light clotted fabric divided by dark, fine grained sediments, and do not display layered microbial matrix features within clots, as is characteristic of many thrombolite classifications.

I ultimately determined that while the thrombolites of the Lower Co-op Creek Limestone Member were morphologically unique, their formational environment was consistent with the shallow marine, slightly turbulent thrombolite reef facies similar to that of their predecessors.

There are many aspects of the Independent Study process which I enjoyed- field work amidst the stunning Utah desert, 50-hour weeks in the quiet isolation of our Scovel Hall paleontology lab, and rigorous scientific study. Beyond all of that, I spent my days working with the fossilized remains of organisms I have been fascinated with for years- holding a deep and almost spiritual respect for the lifeforms that many regard as evidence of the first life on Earth. I owe a great deal of thanks to the Earth Science Department- especially Patrice Reeder for her part in organizing Team Utah 2020, and Dr. Judge for sparking my interest in stromatolites, mentoring me through my degree, and providing superior camaraderie. I thank my superlative advisor, Dr. Wilson, for aiding me over my years at the college both as a professor and as a friend, and for making my passion project a reality.


Aitken, J.D., 1967, Classification and environmental significance of cryptalgal limestones and dolomites, with illustrations from the Cambrian and Ordovician of southwestern Alberta: Journal of Sedimentary Petrology, v. 37, p. 1163-1178.

Kalkowsky, E., 1908, Oolith und stromatolith im norddeutschen Buntsandstein: Zeitschrift der Deutschen Geologischen Gesellschaft, v. 60, p. 68-125.

Kennard, J.M., and James, N.P., 1986, Thrombolites and stromatolites: two distinct types of microbial structures: Palaios, v. 1, p. 492-503.

Theisen, C.H., and Sumner, D.Y., 2016, Thrombolite fabrics and origins: Influences of diverse microbial and metazoan processes on Cambrian thrombolite variability in the Great Basin, California and Nevada: Sedimentology, v. 63, p. 2217-2252.

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Wooster Geologists featured in The Chronicle of Higher Education

The Senior Independent Study process for Morgan Pedroso Curry (’21) and his creative, enthusiastic advisor Dr. Shelley Judge is the subject of an excellent article in The Chronicle of Higher Education this week. (The article may be behind a pay wall for some readers. If you want a pdf copy, we can arrange it.) The images in the article, including the one above, were taken by Wooster’s ace photographer Matt Dilyard. The October 2020 COVID-restricted fieldwork for Morgan’s IS project was recorded in this blog entry by Dr. Greg Wiles.

Well done, Team Morgan!

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A new “living fossil” bryozoan with a Wooster connection

Way back in the summer of 2008, my good friend Paul Taylor (the Natural History Museum, London), John Sime (Senior Independent Study student at the time) and I explored the Pierre Shale (Upper Cretaceous) of the Black Hills region in South Dakota, Wyoming and Montana. We collected numerous conchs and internal molds (steinkerns) of the abundant ammonite Baculites. Some of the internal molds had beautiful networks of connected tear-drops molded in the sediment that had filled the empty shells on the Cretaceous seafloor (image above). These represent skinny bryozoan colonies that lived attached to the inside walls of the shells. These bryozoans were soft-bodied with no hard parts and so were preserved as molds within molds, a kind of taphonomic complexity we always enjoy.

In 2012, Paul and I published a description of these bryozoans, describing them as a new genus and species of ctenostome bryozoan: Pierrella larsoni (see Wilson and Taylor, 2012, and this Wooster Fossil of the Week entry). Above are photographs of ammonite steinkerns showing the undersides P. larsoni (figure 28.1 of Wilson and Taylor, 2012). The specimen above on the left is from Red Bird, Wyoming, and the one on the right is from the Heart Tail Ranch in South Dakota. The scale bars are 10 and 5 mm respectively.

One of the most interesting feature of Pierrella is a remarkable “pleated collar” at the zooid aperture. In the image above, we’re looking at a mold of the collar, which was, like everything else in this bryozoan, soft tissue. From Figure 28.4 of Wilson and Taylor (2012); scale bar = 50 µm.

Now the cool “living fossil” part. Several years later, Russian scientists examined metalliferous seafloor nodules in the deep-sea Clarion-Clipperton Fracture Zone of the eastern Pacific Ocean. This area is receiving considerable attention for deep-sea mining, so teams of ecologists and biologists are surveying the biodiversity in this zone to assess the damage that could be done to this dark ecosystem around 5000 meters deep. Turns out there is a considerable bryozoan fauna down there.

And guess who is a part of this deep-sea community? Pierrella! In 2018, Grischenko et al. published a paper describing Pierrella plicata, a modern species of a genus described  from the Late Cretaceous. Just last week, Schwaha et al. (2021) described the anatomy of this taxon. Above images are from their figure 2: (b) colonies attached to the surface of an arenaceous foraminiferan, showing dispersed zooids and thin proximal cystid appendage; (c) a single zooid; (d) the apertural folds — our Pierrella pleated collar! (Abbreviations: ap – aperture, pca/cd – proximal cystid appendage/cd, z – zooid.)

So our little Cretaceous Pierrella was recognized in the Modern by its fancy apertural collar, which was preserved in an unusual way we still don’t fully understand. The wonders of paleontology.

The modern Pierrella is an example of a “living fossil“, meaning that it very closely resembles an ancient fossil form. Paleontologists are not thrilled with this category, so I keep it in quotation marks. A popular misconception is that a “living fossil” has “not evolved” during some extended interval (about 75 million years in our case here). However, evolution proceeds along all sorts of pathways that are not always possible to see with a fossil-to-living comparison. Internal organs may have changed dramatically and we wouldn’t know. There is also the possibility of evolutionary convergence. Certainly the environmental differences are extraordinary for Pierrella: the Cretaceous version was found in shell interiors in relatively shallow waters whereas the modern form is about 5000 meters deep. Still, the similarities between fossil and modern Pierrella are intriguing.

You know who really likes “living fossils”? Creationists! They have the mistaken belief that these organisms show that no evolution took place between fossil and modern taxa. The fossil to them is just an example of the modern a few thousand years older. Check out the “living fossil” pages for Answers in Genesis and the Institute for Creation Research. I would love to see them add Pierrella to their benighted lists so I could call them out on it.



Grischenko, A.V., Gordon, D.P., and Melnik, V.P. 2018. Bryozoa (Cyclostomata and Ctenostomata) from polymetallic nodules in the Russian exploration area, Clarion-Clipperton Fracture Zone, eastern Pacific Ocean-taxon novelty and implications of mining. Zootaxa, 4484(1), 1-91.

Schwaha, T., Grischenko, A.V., and Melnik, V.P. 2021. Morphology of ctenostome bryozoans: 4. Pierrella plicata. Journal of Morphology. doi: 10.1002/jmor.21344

Wilson, M.A. and Taylor, P.D. 2012. Palaeoecology, preservation and taxonomy of encrusting ctenostome bryozoans inhabiting ammonite body chambers in the Late Cretaceous Pierre Shale of Wyoming and South Dakota, USA. In: Ernst, A., Schäfer, P. and Scholz, J. (eds.) Bryozoan Studies 2010; Lecture Notes in Earth Sciences 143: 399-412.

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New paper on predatory drill holes in Cambrian/Ordovician brachiopods (northern Estonia and northwest Russia)

Once again I’m proud to be on Olev Vinn’s team with this new article on predatory drill holes in Cambrian and Ordovician brachiopods. Predation in the fossil record is always interesting, especially in the early Paleozoic. Here is the abstract with explanatory links added:

Rare Oichnus simplex drill holes occur in mature obolid shells from the Cambrian/Ordovician boundary beds of northern Estonia (Iru and Ülgase) and the uppermost Cambrian of NW Russia (Lava River). The drill holes are significantly more common in the central rather than the marginal regions of the obolid valves. Drilling predators attacked Ungula ingrica in the Kallavere Formation and Ungula convexa in the Ladoga Formation. Failed predatory attacks on obolids were relatively common in the latest Cambrian-earliest Tremadocian of Estonia. Presumably drilling predators at Lava River and Iru differed from those at the Ülgase as indicated by significant differences in drill hole sizes at these locations. Most likely some types of worms preyed on obolids in the latest Cambrian-earliest Tremadocian of Estonia and latest Cambrian of NW Russia. The predation rate (6% to 9%) of studied obolids indicates that they likely had an epibenthic life mode. In addition to Oichnus drill holes in the obolids, there are also common pseudoborings caused by mineral dissolution.

Top image: Single complete Oichnus in Ungula convexa from Lava River, NW Russia, Ladoga Formation, Furongian.


Vinn, O., Holmer, L.E., Wilson, M.A., Isakar, M. and Toom, U. 2021. Possible drill holes and pseudoborings in obolid shells from the Cambrian/Ordovician boundary beds of Estonia and the uppermost Cambrian of NW Russia. Historical Biology (DOI: 10.1080/08912963.2021.1878355).

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Israeli Graduate Student Yael Leshno Afriat summarizes her work in the Middle Jurassic of Israel

For several years I’ve been in the advising circle of Yael Leshno Afriat, a geology graduate student at The Hebrew University in Jerusalem. She has been working in the gorgeous Middle Jurassic units of northern and southern Israel — rocks and fossils I fell in love with way back in 2003. (Search “Israel” in this blog for dozens of posts on our fieldwork, which has included many Wooster students.) In the video above, Yael summarizes her PhD work in a seminar. It is very well done. It makes a beautiful capstone for my extraordinary geological experiences in Israel. Thank you, Yael, for such brilliant and detailed science. I’ve learned so much from you.

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A Day on the Lake

Another day on Browns Lake collecting and downloading data. Nick Wiesenberg (Geological Technician) and I had a quiet morning on a slushy/almost ice covered lake. Nick was trolling for diatoms and the like for sampling productivity in the lake. He was also downloading hourly temperature data (see below) that has been recorded since early July 2020 – in the graph you can see that the lake begins to thermally mix in the fall and is thoroughly mixed by Mid-November. These data are taken from a mooring that Nick established in the middle of the lake at 6 meters water depth. Justine Paul Berina (’22) used these data and others for his Geomorphology project. He wrote a report for our collaborators at the University of Cincinnati that includes his excellent GIS work along with analyses of various logger data. We hope to build on this work and continue the record in the years and decades to come.

Nick trolls the lake to capture the diatoms and other biology in the upper meter of the water column.

Keeping records of the geochemistry of the water throughout the year as well as the sediment raining down through the water column is also part of the monthly routine at the lake.

Nick lowers a Secchi disk into the water column to get an idea of the turbidity of the water.

The many faces of Browns Lake. Thanks to The Nature Conservancy (TNC) for allowing us to do this work and for managing this amazing resource.

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A Wooster Geologist goes virtual

Wooster, Ohio — We can’t let the eventful year of 2020 to pass without some record in this blog of how these difficult times profoundly affected Wooster’s Department of Earth Sciences. Along with the rest of the American educational system, from kindergarten through graduate school, we had to adjust to the extraordinary circumstances of the global COVID-19 pandemic. Here I briefly describe my own experiences since the emergency evacuations and lockdowns of March. My fellow Earth Sciences colleagues (Professors Meagen Pollock, Shelley Judge, and Greg Wiles, along with our administrative coordinator Patrice Reeder and technician Nick Wiesenberg) have their own stories they may tell later. (The top image is of a cameras-on moment in my History of Life class last month.)

I had the least-complicated arrangements for pandemic teaching in our department. For medical reasons I was remote from the start following Spring Break in mid-March. I didn’t set foot on campus for months, teaching entirely from my basement “studio” through my Mac laptop (see above). I was never in the “hybrid” mode of teaching (both in person and online), so the various “pivots” from in-person to remote did not change my routine.

My story starts with a delightful Spring Break field trip to southwestern Utah for Independent Study research with (left to right) Juda Culp (’21), Will Santella (’21), Dr. Shelley Judge and Nick Wiesenberg. We had an excellent and productive time until, midway through, we were called back to Wooster and sent home with the rest of the College. The image above now seems from a lost world. At the end of March we resumed our courses in remote mode, which was new for all of us. This was when I was introduced to the video and course management program Microsoft Teams, which has become a dear (if occasionally frustrating) friend. I thus began to climb the steep virtual learning curve in the second half of the 2020 spring semester.

During the summer my teaching colleagues and I had numerous workshop sessions organized by the College. They covered not only the endless technical video classroom details, but also the principles and goals of virtual teaching. I was a highly motivated participant, mainly because there were so many ways it could go wrong! I learned the most from fellow faculty members who had also endured that post Spring Break remote teaching interval. We were forced to adapt and innovate quickly then, so the time in the summer spent practicing the various modalities increased my confidence.

My basement studio has a dingy real-life background, so I used dozens of virtual backgrounds to hide it. These projected backgrounds themselves became part of the day’s topics, so I had fun choosing from dozens of images I uploaded. This is my favorite one-with-the-bryozoans backdrops.

During the Fall Semester I taught History of Life (two-thirds of my 30 students pictured at the top of this post) and Paleoecology (16 students). My courses were synchronous and live, meaning that at 8:00 am I met virtually with all my students who were in time zones that were compatible. The magical 8:00 am was convenient because places in the far east, like China, were about 12 hours different, giving those students a reasonable evening hour to meet. For most of the semester about half my students were on campus; in the last few weeks most students were in their homes. For those students who could not make our live sessions (it was 4:00 am in Alaska!) I recorded each class through the Microsoft Teams system. I had two office hour sessions every week to answer questions. The system worked with almost every student who could being present live for class. This made teaching much easier with student questions, comments and expressions. We even developed a Google-it tradition where when I couldn’t answer a question someone was assigned to find answers. Within a couple of weeks we had the online-teaching system down with all the muting-unmuting, electronic hand-raising, and cameras on and off. I’m very grateful to my students for making our sessions so much fun, each time transporting me out of my basement into our learning community.

Brachiopod-rich storm layer in the Liberty Formation. Note the circular bryozoan attachment.

I very much missed having rocks and fossils available to students, since I had no labs. Nick made a special solo trip into the Upper Ordovician rocks of southeastern Indiana to collect fossils to mail to each student in the Paleoecology course. A typical slab of brachiopods is shown above. These specimens gave the students some physical objects to associate with the course material. Each student in Paleoecology also gave an online presentation on their course research project, which was fun and extended the range of the course.

Next semester I will be teaching the Sedimentology & Stratigraphy course, again fully remote. I want to expand our use of specimens, so Nick and I assembled 25 sedimentary rock sets, one of which is shown above. Nick carefully cut and labelled the specimens. Each student will receive a sample set, which I plan to use for examples and unknown puzzles. They will also have handlenses and grain-size cards.

This is what 25 sample sets looks like! Thank you again, Nick Weisenberg.

We all hope, of course, that soon we can meet students face-to-face and be back, buzzing with enthusiasm, to our wonderful Scovel labs and classrooms. In the meantime we are making the best of our online tools and communities. Again, this is an account of my experiences. Every faculty member has a unique narrative. We all know how fortunate we are to have positions that enable us to work safely online, and to have such supportive and ingenious support staff as well as extraordinary leaders in the college administration. May the year 2021 bring us all relief and happier times.

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Earth Materials in our built environment – more student photos

Wooster, OH – The first installment of student photos from Earth Materials gave a personalized perspective on materials in our lives. The second installment looks at the built environment around us.

Brick sidewalk.

Devin Henson’s (’21) image shows a beloved Wooster tradition.

Devin writes:

My entry examines how Earth materials are used in the physical infrastructure of the College of Wooster campus and form a part of community tradition, as well as the consequences of this tradition. Multiple footpaths on campus are made of local red bricks, many of which are labeled either “Wooster Ohio” or “Wooster Paver.” These bricks are made of sand and clay and were fired at a high temperature during production. Sand and clay are sedimentary particles of different grain sizes. Sand refers to sedimentary particles with a grain size of 0.0625-2.0 mm, while clay refers to sedimentary particles with a grain size of less than 0.0039 mm. Wooster was the location of a brick company because of its high-quality clay. The hydrous aluminum silicates in this clay produce strong bricks and are thus optimal for the brickmaking process.

It is customary for graduating seniors to dig up and take one of the bricks on campus after completing their Independent Study. Part of the tradition, at least in the way it was passed down to me, is that it is unlucky to take a brick before submitting IS. In addition, the taking of the brick is supposed to happen at night (given that it is technically considered the theft of College property). That last point brings up an important factor in both this tradition and the Earth sciences – sustainability. The company that produced the labeled bricks no longer exists. As such, when the labeled bricks are removed, they are replaced with modern unlabeled ones. Eventually, there will be no labeled bricks left on campus, and the tradition will be forced to change (or will end entirely). In this way, we can see that the removal of Wooster bricks is a microcosm for other issues surrounding Earth materials. Tradition is a powerful force, and it can often lead us to engage in practices that are unsustainable because we value short term gain over long term consequences.


evening view of building remnant

Richard Torres’ (’23) image captures a local landmark.

Richard writes:

King Philip’s Mill (pictured) is one of the many mills in Fall River made of Fall River Granite. Fall River granite comes from the Fall River Batholith which was easiest to mine at the higher parts of the city and because of the dangers of transporting stone downhill most mills along the water front were made of bricks[1]. Most mills are made of brick, but granite was readily available and cheaper to use and was much harder than other granites[2]. The factories would sometimes get the granite from where they where building, this made large basements. Fall River granite looks grey from far away but close up it looks pink due to the felspar it contains[3].

Fall River Granite would provide the foundation for Fall River to become one of the richest cities in the world. Many factories, civil buildings, and Mansions were made of Fall River Granite and many still stand today. Most of the Factory buildings no longer operate as such but have been converted for other purposes. King Philip’s Mill was designated a historic place but now is being torn down to make room for single-family homes.




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