Wooster Geologists

It was a honor to welcome Dr. Nicolás Young (’05) back to the College to be our 44th Osgood Speaker. Dr. Young hails from the Lamont-Doherty Earth Observatory’s Cosmo Lab, where he is a Associate Research Scientist. Nicolás is a leader in developing the analytical side of cosmogenic surface exposure dating and is a gifted and creative field geologist.

His Osgood talk “Disappearance of North Atlantic ice sheets over the last 2.6 million years”  focused on his work with colleagues aimed at trying to figure out what ice sheets may have looked like during past warm intervals in Earth’s recent history, which is particularly important considering Earth’s current climate trajectory. This work is extremely challenging because evidence of small ice sheets has largely been destroyed by repeated episodes of subsequent ice advance. His team has been combining new sampling approaches in the field with evolving geochemical techniques to better constrain what ice sheets may have looked like during the past warm times. He outlined methods of sampling bedrock along ice sheet margins (Barnes Ice Cap) that has become ice free in the last few years, and drilling through existing ice to sample bedrock currently resting beneath extant ice sheets (Greenland). He deftly described how geochemical measurements from these unique samples help determine how often in the recent geologic past the Laurentide and Greenland ice sheets completely disappeared.  This work focused on recent results of a major project Greendrill as well as his ongoing projects on Baffin Island’s Barnes Ice Cap.

News to many in the audience is that the Laurentide Ice Sheet still exists as the remanent Barnes Ice Cap on Baffin Island in the Canadian Arctic. It was the Barnes Ice Cap and the fascinating story of its recent (the last few millennia) history that blew many of us away. Nicolás presented these recent results to our Geoclub. Note the trimline around the extent of the ice cap pictured above in this Sentinel image.

Nicolás speaking to Geoclub on his recent discoveries at the Barnes Ice Cap.

I can’t give the story away as the article is in review (I will post again when it comes out). The gray trimline area seen in the figure above marks a “recent” advance to this 1960 CE position, after which retreat has dominated. Nicolás described the trimline as a knife-edge and that only through careful dating using cosmogenic isotopes could one determine when this “recent” advance of ice began. The significance of this recent advance of the remanent of the Laurentide Icesheet is remarkable and transforms our thinking of Earth’s recent climate history.

We greatly thank the Osgood family for endowing the funds to bring innovative science to our Wooster community each year.

Dr. Mark Abbott and his graduate students Cole and Adeel visited the Wooster Tree Ring Lab with portions of white oak beams from a historic cabin in Pittsburgh. The mission was to tree ring date the outer ring of the samples to determine which calendar year the timber was cut for the structure. Here the Pitt team in the sample prep. lab with the two samples where they polished them for analysis.

Nick Wiesenberg oversaw the dating, which started with a tour in the west wing of the Wooster Tree Ring Lab.

Adeel measured one of the samples – understandably he is amazed with the anatomy of the white oak rings.

Cole measured the other sample measuring ring widths from the screen using CooRecorder. The Pitt group are exports in lake core analysis and both Adeel and Cole are analyzing lake varves, they are also thinking about using this measuring setup for varve analyses (see below).

Nick takes the controls and analyzes the measurement data against our tree-ring database and reveals the date of cutting for the cabin.

The crossdating with our master series shows that the outer ring of the samples were both 1834, at least for the two samples both were cut in the same year after the 1834 growing season so the cabin was likely built shortly after this. The 1698/99 rings are strong markers.

The varves that the Pitt team are analyzing are shown above – they may be annual like tree-rings and their research will extract paleoenvironmental data from these. This core was taken by the group a few weeks before their visit to Wooster in Northern Minnesota where it was tens of degrees below zero. See below.

The coring operation in Minnesota – ~12 inches of ice and 60 feet of water and then a few tens of meters of mud is the sequence through this ice hole.

It was my privilege to join an Estonian-Polish-Chinese-American team interpreting partial soft-tissue preservation of the feeding devices of Silurian cornulitids, which are extinct Paleozoic organisms that constructed small conical, ribbed tubes. Cornulitids are very common sclerobionts (hard-substrate dwellers) in the Upper Ordovician Cincinnatian Group of Indiana, Kentucky and Ohio, so these are familiar fossils to Wooster geologists. Now we know a little bit more about their paleobiology. Our new paper can be downloaded here.

The top image is from Figure 3A of Vinn et al. (2026). It is Cornulites cf. cellulosus (HWR007a) showing a fully protracted likely lophophore (filter-feeding device). Scale bar is 5 mm.

Abstract.–Circular structures observed at the apertures of several Cornulites specimens from the earliest Silurian of China are interpreted as possible fossilized remains of a lophophore with a simple, ring-like morphology. These structures may represent partial preservation of the feeding apparatus, with the absence of tentacle preservation likely resulting from taphonomic processes. The preserved rim surrounding the circular structure likely reflects the thickness of the lophophore and its tentacles, while a neck-like extension visible in one specimen is interpreted as the basal region of the lophophore. Specimens displaying a partially extended lophophore suggest that Cornulites individuals may have been capable of retracting their lophophore entirely into the shell, between feeding episodes, although complete retraction remains speculative. These partial soft-­tissue remains support the classification of cornulitids as lophophorates. However, the available evidence remains insufficient to definitively resolve whether cornulitids are more closely related to bryozoans or phoronids. As the only shelled benthic fossils in the Huangshi deposits, cornulitids seemed to have been opportunistic organisms which were able to colonize and thrive in oxygen-deficient palaeoenvironments following the Late Ordovician mass extinction.

From Figure 4 of Vinn et al. (2026). Cornulites sp. (specimen HWR072a-1) interpreted as showing a partially retracted lophophore. Scale bar is 5 mm.

From Figure 5 of Vinn et al. (2026). Schematic line drawing of Cornulites cf. cellulosus (HWR007a) showing a fully protracted lophophore. Scale bar 5 mm.

Cornulitids are old friends to those Wooster geologists who studied Ordovician fossils in paleo courses. This is the genus Cornulites Schlotheim 1820, specifically Cornulites flexuosus (Hall 1847). It was found in the Whitewater Formation (Late Ordovician, Katian) during a College of Wooster field trip to southeastern Indiana (C/W-148; N 39.78722°, W 84.90166°).

I thank my international co-authors for inviting me to join this team.

Reference:

Vinn, O., Zong, R., Wilson, M.A., Liu, Y. and Zatoń, M. 2026. Partially preserved cornulitid feeding apparatuses from the lowest Silurian of South China support the lophophorate affinities of this enigmatic group. Lethaia https://doi.org/10.18261/let.59.3

Dr. Lyon’s class along with her TAs and in collaboration with the Wooster Art Museum’s director Dr. Marianne Wardle, significantly upgraded many of the fossil and mineral displays in Scovel Hall this past fall.

The classes hard work was revealed in an “opening” on the last day of Geoclub with students presenting their work to the Wooster Earth Scientists.

One of the formerly empty cases in the North entrance of Scovel Hall is now populated with new displays that are Ohio-centric.

Each of the geologic time periods is represented, and in this case, fossils from Ohio are keyed to each period are explained.

A detail of one of the cases and Ohio’s fossils.

Another new addition to Scovel Hall is a case on the first floor with examples of various modes of preservation and remarkable aesthetics in the setup with cards that offer explanations for each specimen.

Modes of preservation was a topic in much of the interpretive materials in the first floor case.

A detail from one of the shelves of the first – floor case.

Departmental technician, Nick Wiesenberg, painted over the not-so-nice pink color that was pervasive in our building, making this almost-three-story-wall shades of blue to provide an oceanic backdrop. Its great to see these displays each day and to see an increase in student, faculty, staff and visitors reading and interacting with the materials. Thank you Dr. Lyon, students and TAs from Paleoecology as well as the Wooster Art Museum and Nick for his support of this project.

Imagine a world with larch trees in the uplands and dawn redwoods in the flats, and bald cypress trees in the wetlands. This existed in the Eocene (~40 million years ago) when the world was warmer, the treeline was at higher latitudes and altitudes, and carbon dioxide in the atmosphere was more than two times Earth’s preindustrial levels. In fact, in the high Arctic where no trees can survive today, deciduous conifers were as lush in terms of carbon sequestration and bioproductivity as today’s rain forests.  Now, imagine a world that is sliding back into the greenhouse after millions of years of relative icehouse conditions.

How can we better understand the role of deciduous conifers in the biosphere and their utility in a warmer world. One “natural” experiment is to use dendroclimatology to infer the response of deciduous conifers to a warmer and wetter world. Secrest Arboretum in Wooster, Ohio has two species of larch trees (Siberian and European) as well as bald cypress and dawn redwood trees. These species are all exotic to Ohio and have been growing in the arboretum in some cases for over 100 years. How do they grow in their new homes? This is the subject of a new paper from the Wooster Tree Ring Lab published in Plants People and Planet.Dawn Redwoods from the Arboretum

The Weather station active in the Arboretum since the late 1800s provided the monthly climate records.

Here is the upshot of the work: Rising temperatures and wetter conditions in the Midcontinent of North America are influencing climate responses in trees. Dendroclimatological analyses of the four exotic deciduous conifer species from Secrest Arboretum, Northeast Ohio help identify past, present, and future climate-tree interactions. Analyses suggest that two larch species have changed their response to climate, whereas dawn redwoods and bald cypress trees are well suited for the present and future climate. This study elucidates tree responses to climate gleaned from a largely untapped source of tree growth in arboreta that can be more broadly applied at other sites as well as facilitate forest management decisions.

This effort included professors, staff and students at The College of Wooster as well as our collaborator and geo-ecologist Dr. Ben Gaglioti from the University of Alaska – Fairbanks. We thank Jason Veil (the curator of Ohio State University’s Secrest Arboretum) and its staff and volunteers for managing this amazing facility and for allowing us to sample the trees. We also acknowledge support of the National Science Foundation, Division of Earth Sciences, Grant/Award Numbers: EAR 2039939, GP-2023154.

Nigel Brush and colleagues have assembled a record of human history in the Walhonding Valley of Ohio (see map below). Along with Jeffrey Dilyard and others, Brush has worked in the region for decades  examining the history of human occupation throughout the Holocene in this part of Ohio. In this latest contribution Brush and colleagues (2025), along with Wooster geologists, has pieced together a story of hunting point technology, resource use, and climate change. A key question of this work focused on the technology of the lanceolate point (see figure below), which was widely used in the Great Plains for hunting bison early in the Holocene (late Paleoindian interval).  Why this same technology was used later in the Holocene about 4.4 to 4.0 ka (~4,400 to 4,000 years ago) in Ohio is a mystery given that bison were not thought to be plentiful. Perhaps the reason was, that during this time of known climate shifts (ie. the 4.2 ka event) bison migrated east into the region and residents adopted the lanceolate technology to exploit this change in resource. The dry conditions in the central plains during this time and expanded prairies into Ohio might explain the lanceolate workshops in the Walhonding River valley and the need for these points. This is one of the hypotheses that the authors put forth to explain the presence of these points in the Walhonding Valley and an idea that could be tested further.

The cover of the Archaeology of Eastern North America (AENA) – the points on the upper left (red background) pertain to the article showing the manufacture of the lanceolate points.  

Map showing the Walhonding River site at the confluence of the Mohican and Kokosing Rivers. The Cox South E-Site is crucial in this study. Downstream also shown are the Honey Run and McConnell sites, which also have documented lanceolate point workshops.

A next-step in this study might be to investigate the ~4.2 ka interval in lake cores from Northeast Ohio to better understand the environmental changes at this time. A strong candidate would be to recover and study that interval as recorded in the sediments of  Browns Lake in southern Wayne County where the other two other abrupt climate changes that define the Holocene are evident. The Younger Dryas (Shane and Anderson, 1993; Lyon et al., 2025) and the 8.2 ka event (Lutz et al., 2008) are well-documented in the lake, why not then the 4.2 ka event? Perhaps a student in Earth Sciences or Archaeology at Wooster will take this on as their Independent Study.

References:

Brush, N., Dilyard, J., Burks, J., Kardulias, P.N., Wiles, G. and Wiesenberg, N., 2025, The Cox South-E Site (33-CS-986): a Late Archaic Lanceolate Workshop in the Walhonding Valley, Coshocton County,Ohio, Archaeology of North America, 53: 129-162: ISSN 0360-1021.

Lutz, B., Wiles, G.C., Lowell, T.V., and Michaels, J., 2007, The 8200 abrupt climate change in Brown’s Lake, Northeast Ohio: Quaternary Research. 67, 292-296, doi:10.1016/j.yqres.2006.08.007.

Lyon, E. C., Wiles, G. C., Wilson, M. A., Lowell, T. V., & Diefendorf, A. F. A HIGH-RESOLUTION LAKE RECORD OF THE YOUNGER DRYAS FROM NORTHEASTERN OHIO. Geological Society of America Abstracts with Programs, 57(7), Abstract #7848.

Shane, L. C. K., and Anderson, K. H. (1993). Intensity, gradients and reversals in late glacial environmental change in east-central North America. Quaternary Science Reviews, 12(4), 307–320.