Wooster Geologists

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.

The global tree-ring community is racking up the papers investigating the utility of the relatively new proxy using blue intensity of annually-dated tree rings. This latest effort is a blue intensity investigation followup of a recent study on ring widths also led by Dr. Santosh Shah of Birbal Sahni Institute of Palaeosciences in Locknow, India. Blue intensity is a proxy that has added a new dimension to thermal histories across the globe including efforts at the The College of Wooster Tree Ring Lab. Shah et al. (2025) used cores extracted from three sites of the Western Himalayan Fir (Abies pindrow) from the Kashmir Valley.

Map from the study showing the location of the three tree-ring sites and the meteorological station (Srinager). The centrally-located Srinager climate station has records of precipitation and temperature spanning 1901-2024, one of the longest in the region.

A figure from the paper showing the beautiful images of earlywood (above) and latewood (below) blue light reflectance for individual rings from the Western Himalayan Fir (Abies pindrow). 

The upshot of the work is that time series of blue intensity values from the latewood of A.Pindrow are strongly correlated with monthly average and maximum temperature series  from nearby climate station (Srinager).  Ring-width are more strongly correlated with summer precipitation and thus blue intensity with its response to late summer temperatures promises to provide a new proxy for thermal histories for the region. These collaborations with Dr. Shah and colleagues have enriched our efforts at the Wooster Tree Ring Lab and we look forward to future efforts.

HYDRO25 the class. On a beautiful fall day the class investigated the South Wellfield – the mission was to take water levels from 15 observation wells and sample the groundwater, surface water and water emanating from the airstrippers. Isotopic analyses of these waters are pending. The photo above is the Falls at Apple Creek aka Effluent from an Airstripper.

HYDRO25 – here is a photo of the hand-picked teams assigned the tasks described above. The team is united by the bucket auger that was used to auger down to the confining layer of the Wooster Aquifer.

The confining layer is that far down – this group made short work of the task and brought up the pristine lake clay that is the confining layer.

Here is the clay brought up by the team. It is organic rich and we really should pick it for organics.  Radiocarbon ages of the organics will help us understand the timing of the lake that existed in the valley – Glacial Lake Killbuck.

Our primary objective was measuring water levels in the confined Wooster Aquifer, however here we are measuring the water table that is a perched aquifer on top of the clay. Just a kilometer aways is a BTEX plume on top of the clay that is actively being remediated.The observation wells are all completed in the confined Wooster aquifer, and here the team is sneaking up on observation well #4. The levees to Apple Creek are in the background.

We also had a team in the Apple Creek measuring discharge and probing the bottom of the stream for the clay confining layer. What a welcoming team of stream gaugers.

The team bailed a few of the wells to sample the water.  We will obtain the stable isotopes of the various waters sampled to investigate the origin of the waters. This was last done by the USGS decades ago.

The airstrippers, installed to remove VOCs from the water, are filled with these “wiffle balls” designed to atomize the waters which are then “stripped” of contaminants via compressed air blowing through the column.

One last shot of the Auger team under a big Wooster sky with their feet firmly planted in a recently harvested no-till soybean field with the water treatment plant and its anaerobic digested in the far background.

Special thanks to our bus driver Bud and to the Water plant for permission to enact this lab for HYDRO25.

At the alumni reception – a reunion.

Elliot Miller (Wooster) presenting his IS work on geochemical analyses of palagonite and potential applications to Martian exploration.

Mary Palmieri (Wooster) investigates the linkages of tree rings and cloudiness in Northeast US.

Lynnsey Delio (Wooster) is investigating the linkages between coastal Alaskan tree-ring records and the monthly Lake Huron and Michigan levels.

Lauren Segura (Wooster) presents her work using crystal size distributions to help determine the origin of extrusive rocks in Iceland.

Ihaja Metz (Wooster) is working on using the XRF at Wooster in determining water chemistry in natural groundwaters.

In addition to the presentations by Wooster students and faculty – four Keck Geology Consortium students who worked at Wooster in the summer of 2025 presented results. Here Dexter Pakula (Carlton College) presents his study linking modes of climate variability in the Indian Ocean to climate variability in Alaska.

Lev Sugerman-Brozan (Colorado College) explains the results of his work comparing tree-ring reconstructions Gulf of Alaska temperature variability and model simulations focusing on intervals of strong volcanic forcing.

Landon Vaughan (Trinity University) explored the record of volcanic cooling of the late 1690s volcanic event(s) their signature in the rings of yellow cedar trees and linkages with Tlingit oral histories.

Izzy Held worked on the feasibility of using costal tree-ring records from the Gulf of Alaska to reconstruct Mendenhall River flow from Juneau Alaska.

We are grateful to the many alumni for their support and their contributions that helped to fund the travel and stay in San Antonio.