Investigation of a Ring Width Yellow Cedar (Cupressus nootkatensis) Series as a Record of Coolings Associated with Volcanic Eruptions

gwiles June 7, 2025 4:10 pm

Figure 1. Title page of Amanda’s thesis including one of the key figures.

Amanda Flory (class of 2025) completed a thesis that investigated the interplay between the pace of the ocean-atmosphere climate in the Northeast Pacific that is dominated by Pacific Decadal Variability along with the volcanically-forced coolings inferred from tree-ring records. Her title page (above) summarizes the results with several known volcanic intervals linked with decade-long coolings. These coolings are inferred from a tree ring-width series located in coastal Southeast Alaska (Dude Mountain, Ketchikan, Alaska). In addition to her thesis work Amanda presented her results at the meeting of the Geological Society of America in the Spring of 2025. The take-home here is that the variability as recorded in the tree-ring record appears to be a combination internal variability of the Northeast Pacific [1] and volcanic forcing [2] contributing to the decadal variability in the climate.

Figure 2. The author (left) cores a yellow cedar (Cupressus nootkatensis) – Nick (middle) and Proto provide support.

Figure 3. Comparisons of Sitka, AK temperature records for the months of December through October of the growth year correlated with the Dude Mountain ring-width record.

This climate/tree-ring comparison (Figure 2) examines the moving correlation over time (since 1857) is based on a running 35-year correlation. Correlations change from positive (blue) to negative (red) and back to positive. This non-stationary response temperature is puzzling and is likely complex reflecting the ecological and climate-related thresholds at the site. Amanda explored the correlation between ocean heat content ([3]; see Figure 1: title page) and tree growth. The strong and steady relationship between the ocean heat content and growth suggests that the near-coastal tree-ring site is dominated by the ocean-atmosphere system immediately offshore.

Figure 4. Key volcanic events that correspond with decades of cooling.

As is the case with most theses, more crucial questions are raised and will continue to be investigated. These include continuing the examination of the yellow cedar climate response as well as applying new analyses that seek to tease out the volcanic response from the internal response of the Pacific Decadal variability in the record.

Acknowledgements: This work was supported by the National Science Foundation Grant AGS-2002454. We would like to thank Klawock’s Alaskan Youth Stewards (AYS) group for their expertise and guidance while conducting field work.

References:

[1] Schneider, N., and Cornuelle, B.D., 2005, The Forcing of the Pacific Decadal Oscillation:, doi:10.1175/JCLI3527.1.

[2] Wang, T., Otterå, O.H., Gao, Y., and Wang, H., 2012, The response of the North Pacific Decadal Variability to strong tropical volcanic eruptions: Climate Dynamics, doi:10.1007/s00382-012-1373-5

[3] Levitus, S. et al., 2012, World Ocean heat content and thermosteric sea level change (0–2000 m), 1955–2010: Geophysical Research.

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Browns Lake Study by Grace Neuman

gwiles May 15, 2025 11:30 am

Guest Blogger Grace Neuman: From mossy bogs to forgotten fields, the landscape of Northeastern Ohio holds buried stories. My Independent study, examines how two centuries of post-settlement human activity have altered the region’s ecosystems, and how we can still see those imprints today.

I investigated various ecological and historical data sources, such as tree rings, sediment cores, soil textures, soil chemistry, and radiometric dating, to trace land use patterns and forest disturbance over time. These scientific methods helped uncover both natural and human-driven shifts in the region’s environmental conditions.

Me in the lab with sediment grain size analysis equipment (PARIO).

My work focused on Brown’s Lake Bog Preserve, located on Browns Road in Shreve, Ohio. This Nature Preserve harbors remnants of Ohio’s post-glacial ecosystems and is one of the last few acidic bog ecosystems remaining in Ohio. The LiDAR map above shows the location of the Bog (BB) and the lake (BL). This kettle lake is surrounded by kames.

Sediment core (left) and various measurements (right) provided by Erika Freimuth. The sediments here record the transition of the surrounding landscape from an organic-rich bog (black mud) to a brighter clay/silt blown into the bog when the land was cleared. This profound change took place about 1820 dated by Pb-210. The blue line on the left is magnetic susceptibility and tracks the increase in eroded soil to the basin whereas the red line (organics) decreases.

The gain size analysis of the sediment deposited in the basin closely after 1820 is composed of mostly clay and silt. This grain size is consistent with eroded soils from the surrounding farmed landscape.

The dating with Cesium-137 and Pb-210 by Dr. Josh Landis of Dartmouth College yielded interesting results.  The disruption about 1950 in the graph above suggests erosion and and increase in mass accumulation of sediment likely linked to logging in the basin.

Within the Preserve is a white oak stand of trees growing on the kames. These trees were witness to the land use changes. The release in tree growth about 1820 is consistent with the inferred land use change, also not the bump in ring-widths about 1950 when the forest was again selectively logged.

One of the classic kames surrounding the bog. This work was supported by the National Science Foundation and the Copeland Fund of The College of Wooster. We thank The Nature Conservancy for management of the site and permission to core the lake. Thanks also to T.V. Lowell for procuring the core and N. Wiesenberg for his help in the lab.

 

 

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The geomorphology of Mount Eagle, Virginia, and the Civil War

Mark Wilson May 10, 2025 2:37 pm

Alexandria, Virginia — This is my second post about my new home in the Mid Atlantic. I retired from The College of Wooster in August of 2024, and just three weeks ago my wife and I moved from Wooster, Ohio, to Alexandria, Virginia, city just across the Potomac River from Washington, DC, to be closer to family. As a Wooster Geologist, I want to understand my new location in terms of the geology and how that geology has affected human history. Our condominium complex (never thought I’d say those three words together!) is on a dissected ridge called Mount Eagle. In the Civil War map above, Mount Eagle is rendered “Eagle Hill”. We will get to what all those fortifications are about!

My earlier blog post on the geology of Mount Eagle describes how I learned that the gravels on the top of this hill are Pliocene fluvial terrace deposits from the ancient Potomac River as it downcut its wide valley. The geomorphological result is an elevated ridge with a flat top and steep sides overlooking the modern Potomac and the cities of Alexandria and Washington. You may be seeing now why forts are going to be part of this story!

Just this week this sign appeared on the main hiking trail around the condominium campus. Dr. Greg Wiles taught me to be a bit suspicious of tree dates that do not involve tree-ring counting, but it is quite plausible this tree is at least 200 years old.

Here is more of the tree’s trunk. It is the widest tree I can see in our woods. Here is some information on Quercus montana. It likes rocky settings and ridgetops, which fits the setting for this specimen.

Mount Eagle was in the late 18th and 19th centuries a prominent site in the Alexandria area. Bryan Fairfax, a Scottish lord and clergyman, built a mansion and plantation on the top plateau overlooking the Potomac Valley. He was a buddy of George Washington, who visited often from his own nearby plantation at Mount Vernon. Yes, I’m now living in one of those “George Washington Slept Here” places. However, I’m haunted by the fact that there were also at least a dozen enslaved people on this land prior to the Civil War, and that Alexandria had one of the largest slave markets in the country.

This is a photograph of Alexandria looking south sometime between 1861 and 1865 (Library of Congress). In the background you can see the ridges that include Mount Eagle. On May 24, 1861, immediately after Virginia voted to secede from the United States, Union troops crossed the Potomac and occupied the city and surrounding region. Alexandria became the first Confederate city to be occupied (“liberated” would be my term). This was an essential move because the city had a critical port and was the terminus of two railroads. Also, those ridges to the south of the city could be fortified by the Confederates and used to shell Alexandria and Washington. Alexandria quickly became a logistical hub for the Union Army and Navy in the East.

Strong Confederate forces assembled south and east of Washington. Richmond, Virginia — the capitol of the Confederacy — was only about a hundred miles to the south of Washington. The first major battle of the Civil War was fought on July 21, 1861, at Bull Run, about 30 miles west of Alexandria. It was close enough that civilian sightseers from the Washington area could travel to the battle for entertainment. To the shock of the northern establishment, the Confederates forced the Union Army into a catastrophic retreat, winning the battle and immediately threatening the city of Washington. The capital of the United States was quite suddenly vulnerable to an attack from the Rebels. Now that geology we learned plays its critical role.

Soon after Union troops occupied northern Virginia in May 1861, they began to clear the woods and dig artillery emplacements in the ridges south and east of Alexandria and Arlington. The defeat in the First Battle of Bull Run showed that these fortifications must be extended and improved rapidly. General George B. McClellan, the new commander of the Army of the Potomac, ordered an extensive and elaborate ring of forts, redoubts and trenches to encircle the capital region, from the left flank south of Alexandria circling around to southeastern Maryland. The map above shows the dozens of forts in the Washington region, all designed to be within an easy cannon shot of each other and eventually all connected by trenches. From 1862 to the end of the war in 1865, Washington was the most fortified city in the world. The red arrow on the map above points to the Mount Eagle area.

This sketch map by an unknown Union officer is now in the Library of Congress. Southwest of Alexandria is Fort Lyon, one of the largest forts, sitting atop “Eagle Hill”, which is our Mount Eagle. You can see its strategic value as it controlled land access to the capital and Alexandria from the west and south, and could shell targets in the Potomac River.

In this closer view of another map, the flat surfaces of the fluvial terraces are apparent. They made it much easier to construct fortifications on the ridge heights. In the upper right of this map are two buildings referred to as “Johnsons”. The larger one is the Mount Eagle mansion built by Bryan Fairfax. The modern condominium complex where we live occupies the footprint of that mansion and extends west to part of Fort Lyon.

Here is a view inside Fort Lyon in 1863 showing the 26th New York Infantry assembled on the parade grounds. (Library of Congress.)

These gun crews are on station in Fort Lyon. This is an undated image from the Library of Congress. Despite several alarms, Fort Lyon and this southern end of the Washington defenses was never attacked. The forts, then, did their job of protecting the capital. There was, unfortunately, significant loss of life anyway at Fort Lyon. Over twenty soldiers were killed and twenty wounded on June 9, 1863, when the powder magazine exploded by accident.

What is left today of Fort Lyon and its associated defenses? The fort itself is completely covered with modern structures, mainly the Huntington Metro Station, some office buildings, and part of the condominium campus. The above sign is the only visible marker of the fort.

However, a tiny bit of the defensive system can still be seen. In this map Fort Lyon is seen connected to the smaller forts Weed and Farnsworth. Fort Farnsworth is connected by entrenchments to Fort O’Rourke. Between Farnsworth and O’Rourke is a cannon battery in earthworks along the trench.

The site of that battery has been preserved in this patch of woods on the western edge of Mount Eagle Park.

Inside these thick woods are the remnants of gun emplacements. It doesn’t show well with photography because it is so overgrown, but the trench is in the middle, foreground to background. On the right side is the embankment behind which the cannons were placed. See below an example of such a redoubt.

This image is from another Washington fort showing how the Mount Eagle battery guns were positioned.

So now I have at least an early understanding of the surficial geology of our new home on Mount Eagle in Alexandria, Virginia. Our steep hill is topped by a plateau formed from a fluvial terrace of the ancient Potomac River. This explains the topography and the abundant pebbles, cobbles and boulders on the surface. These terraces are higher than Alexandria and Washington to the north, so occupying them in force was necessary to defend the capital from Confederate attack. The flat terrace surfaces and deep, gravelly soil made construction of large fortifications relatively easy. I now feel at least somewhat oriented in my new Virginia home!

 

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Wooster Geologist in northern Virginia

Mark Wilson May 6, 2025 2:54 pm

Alexandria, Virginia —Last August I retired from The College of Wooster after 43 years of service. It was difficult to detach from the wonderful Earth Sciences department after planting such deep roots in this extraordinary community of teacher/scholars. Then two weeks ago, my wife Gloria and I moved from Wooster to northern Virginia to be close to our daughter, son-in-law and 13-month-old grandson. It has been quite a transition, leaving so many friends to go to a new home on the East Coast — to go from the rural Midwest to the urban Mid-Atlantic. As with all such changes, though, there are opportunities to explore unfamiliar communities, ecosystems, and, of course, geology. I plan to continue contributing to this blog from my new perch just ten miles south of the White House on the west shore of the storied Potomac River (pictured above at Belle Haven Park).

I began my new chapter with questions about the geological context of where we now live. We’re now part of a great hive of people in a condominium complex in Alexandria south of its Old Town. This is our building. Very different from our house on Forest Drive in Wooster! The complex (which has three other residential units like this one) is on a flat-topped hill called Mount Eagle.

The blue dot on this Google aerial image shows our condo in one of the four main buildings. The complex is surrounded by woods, which make a nice buffer from the busy roads just outside. Despite 2200 people living here, the first impression of the grounds is deep greenery.

The red arrow on this USGS topographical map points to Mount Eagle, which rises about 50 meters from its base to a plateau on the top.


The veneer of woods around us on Mount Eagle is so thick it is hard to see just how deep and steep the ravines are on the north and south sides of the hill.


So what is the underlying geology of Mount Eagle? There are no rocky outcrops. Where the vegetation is thin we see pebbles, cobbles and small boulders like these.


Rarely this gravel is cemented into thin layers of coarse sandy conglomerate, like this.


The clasts have their own geological histories. For example, this is a cross-bedded quartzose sandstone boulder. The cross-beds were not formed here but are instead derived from some distant source rock for the gravel.


Occasionally there are even trace fossils evident in these boulders. These burrows were formed in a fine sandstone that was eroded to produce this boulder deposited later on what is now Mount Eagle.


At this point a geologist now turns to geologic maps for information about a spot of local geology. Virginia has a wondrously diverse and complicated geology. The geology of Ohio is much simpler! Virginia is deeply tectonized in the west (as seen in the Blue Ridge Mountains) and dominated by extensive sedimentary basins in the coastal plain of the east. I have a lot to learn here. The star on the map shows the location of Alexandria. We need a more detailed map to sort out the geology of Mount Eagle.


Now with this map of the surficial geology of Alexandria and its region we can see the detail we need to make sense of our local cobbles and pebbles. The red square contains Mount Eagle. Along the south side of the square is a triangular patch of orange. On the key of the map that color represents the “Beverley Hills terrace (Pliocene?)”, which is mostly “coarse cobble gravel …” (This map and the next are modified from maps on an excellent geology site by the city of Alexandria.)
This is a map showing the terraces of the Alexandria area. The Beverley Hills Terrace is the easternmost, and Mount Eagle is conveniently under the “Tt5” label. These terraces are fluvial terraces carved and deposited by the ancient Potomac River.

 

This Wikipedia image of fluvial terrace deposits shows how they form along the banks of a down-cutting river.”


So there we go. This coarse gravel was deposited roughly 2-3 million years ago by the ancient Potomac River. The quartz-rich clasts are classic survivors of a long erosion, weathering and transportation process from their original deposition locations in what are now the Blue Ridge Mountains far to the west. I’ve learned something about the geology of Mount Eagle and the geomorphic history of this region.

Next: How did this geological context affect the human history of Mount Eagle?

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New Survey of Biomarkers in Lakes Across A Large Swath of North America

gwiles May 4, 2025 10:21 am

The link to the full publication and supporting data can be found here.

HBI Wizard, Aaron Diefendorf (University of Cincinnati) on the forest edge of Browns Lake, Wayne County Ohio. Dr. Diefendorf and Dr. T.V. Lowell and their students (Dietrich, 2023; Corcoran et al., 202o; Freimuth et al., 2021) are the force behind investigating biomarkers secreted from diatoms in lake as records of past precipitation changes. This basic research is impressive given they are chasing molecules (shown below) that are secreted from microscopic diatoms in lake waters and in complex organic sediments that accumulate at the bottom of lakes. Wooster Geologists have participated in the field monitoring and diatom work resulting in several Independent Study projects.

Diatom-derived highly branched isoprenoids (HBIs) are lipid bio- markers found in marine and lacustrine sediments. Most of the work on these has been done in marine environments and the UC group is now extending study to lake settings.

The sampling team on a North Dakota Lake.

Locations of the 50 lakes sampled in this study (A) and expanded maps of the Indiana lakes (B) and Adirondack region lakes (C).

The University of Cincinnati team and collaborators from St. Lawrence University coring on an Adirondack lake on a spectacular fall day. T.V. Lowell (orange gloves) is the core boss who has provided “high-quality” mud from the bottom of lakes and bogs across the planet and for several Wooster classes and student theses.

References:

Corcoran, M.C., Diefendorf, A.F., Lowell, T.V., Freimuth, E.J., Schartman, A.K., Bates, B. R., Stewart, A.K., Bird, B.W., 2020. Hydrogen isotopic composition (δ2H) of diatom- derived C20 highly branched isoprenoids from lake sediments tracks lake water δ2H. Organic Geochemistry 150, 104122.

Dietrich, W., 2023. Assessing controls on lacustrine diatom biomarkers. MS Thesis. University of Cincinnati.

Freimuth, E.J., Diefendorf, A.F., Lowell, T.V., Schartman, A.K., Landis, J.D., Stewart, A. K., Bates, B.R., 2021. Centennial-scale age offsets of plant wax n-alkanes in Adirondack lake sediments. Geochimica et Cosmochimica Acta 300, 119–136.

*This research was supported by the US National Science Foundation grant EAR-2039795 to the University of Cincinnati and EAR-2039939 to Wooster*.

 

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New Publication from the Wooster Tree Ring Lab

gwiles April 26, 2025 10:31 am

The lead author of this work, Fred (Wenshuo) Zhao, photographed in front of the Mendenhall Glacier in Juneau, Alaska. The logs at his feet, recently exposed by the retreating ice, are the subject of his undergraduate thesis and this publication. The College of Wooster Tree Ring Lab has an extensive collection of subfossil wood (trees run over in the past by glaciers) and this wood is often stained by exposure to the elements altering the color of the wood. This alteration inhibits the measurement of tree-ring parameters like blue intensity measurements. Measuring blue intensity (BI) has been shown to improve climate reconstruction and improve general tree-ring dating (Wilson et al, 2017, 2019). Fred, with the great help of Junpeng Fu and Nick Wiesenberg at Wooster, chemically treated the wood showing an improved climate signal in the BI measurements after treatment.  This paper describes the process and evaluation of this chemical method using wood sampled from along the Gulf of Alaska as an example.

 

Degrees C

One of the clever tests that Fred performed to evaluate the improved climate signal was to compare climate signal of latewood blue intensity measurements before soaking in hydrogen peroxide (graph on the left) and after soaking (right) with temperature data. Since the tree-ring samples date back to 1050-1350 CE, we were not able to compare the tree-ring measurements with actual (observational) climate records of temperature. So Fred used a published tree-ring based temperature reconstruction for the Gulf of Alaska (Wiles et al., 2014) for the comparison. The graphs show an improved climate signal (R=0.56 to 0.66) after the treatment. Several other statistical metrics described in the paper are consistent with this improved climate signal. This work is a significant step towards improving the study of climate and the ability to use tree-rings to date glaciers, mass movements, earthquakes, and volcanic events along the Gulf of Alaska and into the interior of the Northern North American continent.

Fred and Junpeng (Jerry, also a former Wooster student) are now working toward getting their PhDs at the University of Oklahoma – their research focuses on the use various aspects of biochemistry in understanding the worlds oceans and climate.

References:

Wiles, G.C., D’Arrigo, R.D., Barclay, D., Wilson, Jarvis, S. K., Vargo, L., Frank, D., 2014, Surface air temperature variability for the Gulf of Alaska over the past 1200 years: The Holocene, DOI:            10.1177/0959683613516815.

Wilson, R., D’Arrigo, R., Andreu-Hayles, L., Oelkers, R., Wiles, G., Anchukaitis, K and Davi, N., 2017, Blue Intensity based experiments for reconstructing North Pacific temperatures  along the Gulf of Alaska: Clim. Past Discuss., doi:10.5194/cp-2017-26.

Wilson, R., K Anchukaitis, L Andreu-Hayles, E Cook, R D’Arrigo, N Davi, L Haberbauer, P Krusic, B Luckman, D Morimoto, R Oelkers, G Wiles, C Wood, 2019, Improved dendroclimatic calibration using blue intensity in the southern Yukon. The Holocene, 29(11), 1817-1830, https://doi.org/10.1177/0959683619862037.

 

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From Glacial Lake Craigton to Browns Lake Bog

gwiles April 20, 2025 9:46 am

Last Monday there was a power outage on campus and classes were cancelled, despite this news our afternoon lab period fieldtrip went on as planned. The trip consisted of a field trip led by Nigel Brush (retired from Ashland U. and Wooster). It was a great trip on a beautiful day and we greatly appreciate Dr. Brush’s time and willingness to share his expertise of the history of our region. 

Above the students survey ice stagnation features from the top of a kame.

View of a kettle from the rim of the kettle. The kettle is located on the map below (lower right).

Map (soilexplorer.net) showing the kame and kettle terrane with the esker in the middle. The kame shown in the photo above is the circular feature in the lower right.

The Mohicanville Dam is located in one of the former Lake Craigton spillways. The dam, located in this hours glass spillway, is the site of the narrowest reach of the gorge and controls floodwaters that would otherwise inundate communities to the south. Extensive flooding in 1913, in part, prompted the US Army Corp. to build this and other flood control structures.

GoogleEarth image of the Mohicanville Dam.

Map above (from soilexplorer.net) the amazing stagnant topography of the Browns Lake Bog area. Now that Dr. Brush pointed out some additional features in the region we wonder is the feature in the upper left is an esker?

The group at Browns Lake Bog discussing the old growth forest on the kames and the relatively new forest in the flats. The the post-glacial history recorded in the sediments and tree-rings at the site has been an extensive subject of research at the College of Wooster in collaboration wit hthe University of Cincinnati over the past two decades.

The upshot of the bog ecology is that during the time of European Settlement lake core records show a pronounced influx of silt and clay from surrounding soils and the fertilization of the nutrient-limited bog allowing the establishment of vascular plants (trees and shrubs) and the setting that we see today. This model was originally put forth by by Ireland and Booth (2012) and is the subject of Grace Neuman’s (’25) IS project (blog coming soon).

Reference: Ireland, A.W., Booth, R. K., 2012, Upland deforestation triggered an ecosystem state-shift in kettle peatland: Journal of Ecology, vol. 100, p. 586-596. 

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New Paper on Oaks in Ohio – A Nostalgia Tour

gwiles April 12, 2025 11:04 pm

The College of Wooster Tree Ring Lab faculty, staff and students have teamed up to publish results of  an analysis of a network of tree-ring sites in Northeast Ohio to ask the question what is driving the changing climate response of the trees. The tree-ring sites include young (100-year-old) white oaks in Secrest Arboretum, Wooster, two sites of post-settlement age (about 200-years old) from Wooster Memorial Park and The Kinney Field Park both in Wooster and four old growth sites (>300 years old) from some of our favorite sites including The College of Wooster campus, Cornerstone Elementary, Browns Lake Bog, David Kline’s (the author) old growth forest on his farm and Johnson Woods the largest tract to old growth white oak forest in Ohio.

The upshot of the study reveals that the one- hundred-year-old white oak stand in Secrest Arboretum, along with two second growth stands have consistently responded positively to summer (June-July) precipitation over the past century, whereas the four nearby old growth sites have lost their moisture sensitivity since about the mid 1970s. This “fading drought signal,” which has been previously reported by Maxwell et al. (2016), appears to be more a result of the legacy of land use at the individual sites rather than tree age. The younger oak stands and their relative sustained drought sensitivity is also related to their history of recently attaining the canopy and similar responses associated with intervals of selective logging. All sites are strongly, negatively correlated with summer (June- July) maximum monthly temperatures.

Paleoclimate class (2021) at Johnson Woods Orrville Ohio. One of the key sites in the paper and one of the key sites in the Midwest. Originally cored by Ed Cook (Lamont-Doherty Tree Ring Lab) in 1980, the site has been updated by The College of Wooster Tree Ring Lab and by Justin Maxwell at the Indiana University Tree Ring Lab. Students sampling the remanent white oak stand at Browns Lake Bog a site managed by the Nature Conservancy. 

Coring the second-growth white oaks in Wooster Memorial Park.

Another second growth site is within the Wooster city limits at the Kinney Field Park.

The College of Wooster campus maintains an impressive stand of old growth white oaks on its campus. Here members of the Holden Arboretum Tree Corps sample one the the impressive old trees.Secrest Arboretum (on the Wooster campus of the CFAES) is one of our favorite sites to cores trees. Many of the trees from  all around the world have lived in Ohio for over 100 years. Here one of the coauthors cores a white oak planted about 100 years ago.

A final word on this study. Future warming in the Midwest is projected to see increases in spring precipitation, likely decreases in late summer precipitation, which if coupled with an increase in maximum summer temperatures would increase the moisture stress on these trees. Our examination of these varying climate responses with respect to site characteristics and forest age can help future assessments of tree health and the forest’s ability to sequester carbon, as well as facilitate efforts to reconstruct climate by using a range of tree sites for intervals when sensitivity in old growth sites is lost.

These data from the sites in Northeast Ohio are available in the International Tree-Ring Databank maintained by NOAA and many of these records have been incorporated into the North American Drought Atlas contributed to the larger climate science community by Ed Cook and colleagues.

References:

Maxwell, J.T., Robeson, S.M., Harley, G.L., 2016. On the declining relationship between tree growth and climate in the Midwest, United States: the fading drought signal. Clim. Chan. 38, 127–142. https://doi.org/10.1007/s10584-016-1720-3.

Acknowledgements: This work was funded by The College of Wooster, NSF Geopaths and NSF – EAR 2039939 grants.

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GSA – Erie 2025

gwiles March 31, 2025 8:48 pm

Wooster Earth Scientists traveled to Erie PA to attend the joint Northeast /North-Central Geological Society of America for a weekend of geology talks, posters and fieldtrips.

 

Above Grace presents her senior Independent study research entitled “A LAKE RECORD OF ENVIRONMENTAL CHANGE IN NORTHEASTERN OHIO SINCE EUROPEAN COLONIZATION” abstract here.

Proto presented ALASKA’S FIRST WESTERN RED CEDAR TREE-RING CHRONOLOGY described here. 

Proto here describes the winter signal that they discovered in the tree-ring record of the red coastal cedar from Southeast Alaska.

Lauren describes her Alaskan tree-ring work on the southern coast of central Alaska.

Lauren’s poster FIVE NEW MOUNTAIN HEMLOCK TREE-RING CHRONOLOGIES FROM SOUTHEAST ALASKA: NEW RECORDS OF CLIMATE – here she just shared the research with alum Nick Fedorchuk who now a professor at Southern Connecticut University.

Evie (foreground) with Anika and Ihaja looking on – explains their work on four deciduous conifers from Secrest Arbooretum. These trees may be key players in future high CO2 environments in a warming world as they were in the past. the title: USING DENDROCLIMATIC ANALYSIS OF EXOTIC DECIDUOUS CONIFERS IN AN ABORETUM TO DOCUMENT TREE GROWTH IN RESPONSE TO CLIMATE CHANGE, NORTHEAST OHIO, USA described in their abstract here. 

Amanda’s IS work is explained in this poster and her lightening talk is shown below. The title CAN VOLCANIC EVENTS FORCE DECADAL COOLING IN THE NORTH PACIFIC? is described in this abstract.

Linking short scale (1-2 year cooling forced by volcanic events) appears to serve to force cooling SSTs in the North Pacific that can persist for a few decades.

Wooster faculty also presented results of research – above Dr. Eva Lyon describes her work on a Pleistocene lake from West Virginia. Her title PALEO-LAKE BUCKEYE: A NEW SEDIMENTARY ARCHIVE OF PALEOENVIRONMENTAL CONDITIONS ACROSS THE PLEISTOCENE-HOLOCENE TRANSITION IN THE CENTRAL APPALACHIAN MOUNTAINS and abstract can be found here. . Wooster students are now working on these lacustrine sediments. G. Wiles also presented: PROGRESS IN USING TREE-RING CHRONOLOGIES TO RECONSTRUCT LAURENTIAN GREAT LAKE LEVELS, which focused on reconstructing Lake Erie levels using tree rings. Tim Fisher (U.Toledo) also presented collaborative work with Wooster on Lake Erie water levels here.

 

Drs. Lyon and Wiles attended a fiedtrip to Presque Isle during the meeting to examine the coastal erosion. This trip will serve as a planning trip for a potential future fieldtrip of a combined course in Paleoecology and Hydrology in the fall of 2025.

A breakwater offshore dampens the power of the waves and the piles perpendicular to shore slow the longshore drift and sediment loss of the beach.

This van at the visitor’s center is a map of the features viewed on the trip – Presque Isle and, on the Canadian side, Long Point, are spits and tombolos located on glacial moraines that formed about 14,000 years ago during deglaciation of the Laurentide Icesheet.

It was a lively group – of students, professionals and faculty.

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Coring Eastern Hemlock (Tsuga canadensis) in Wooster Memorial Park (aka Spangler)

gwiles March 15, 2025 9:41 pm

Wooster Memorial Park has been a great resource for The College of Wooster Earth Sciences (ESCI), Biology among others. Here the ESCI course in Paleoclimate, under permit from the Friends of Wooster Memorial Park, sampled 20 second growth Eastern Hemlock with the aim of determining the climate response of the species in the Park. A recent publication by the Wooster Tree Ring Lab incorporated results from past sampling in the park that was concerned with the changing climate response of white oak trees. This oak study can be found here Wiles et al., 2025.

Lidar Map of Wooster Memorial Park – the green field in the west of the park is the approximate location of tree-ring sampling.

 


The class took advantage of a spectacular day for the sampling.


Nick demonstrating the coring technique using an increment borer.


Another perfect core, once trained, the five groups went into sampling mode.


For most of the group, this was their first experience coring and it was clear some were naturals at the technique.


First-ever core reveal photo – a proud dendrochronologist.


Another first.


Coring for the first time.


Coring and at the same time keeping a sharp eye out for wildlife.


A first – ever core safely archived in a reusable plastic straw.


Even the TA was caught working in this photo.


Deep in the hemlock forest – group three assesses another hemlock.


On the cliff’s edge tree workers and tourists confer.


Another core reveal photo.


Here five sizeable hemlocks lie in a row – blown down by the summer storm of 2022.


All the root throw from hundreds of downed trees is significantly changing the sediment budget in the tributaries.

From the storms and trees killed by the emerald ash borer there is plenty of wood for log jams.

A portion of the park was used for raising shade trees back in the day. Here is one of the shade trees that remains.


Reflecting on the completed coring and anxious to get to the lab work.


One of the many, diverse rocks in Rathburn Run. Special thanks to the Friends of Wooster Memorial Park and the City of Wooster for maintaining the park and allowing us to sample there.

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