The Dendrochronology Team of Wooster Geologists makes its television debut

February 28th, 2013

Gwiles022813aBarn Detectives” is a recent episode of the television show Our Ohio, and it features Dr. Greg Wiles and his team of crack dendrochronologists. You can view the video by clicking the link. It is very well done. The project described in the program is the dating of the Emerson barn in Apple Creek, Ohio. These Wooster scientists study the tree rings in the beams which were used in the original structure. Careful analysis of these rings will show the year the old-growth trees were cut for timber, and thus the date of the building. This work not only gives the Emerson family a date for a treasured building, it also provides additional dendrochronological data for studying climate change in the last two centuries.

Nwiesenberg022813Our geological technician Nick Wiesenberg provides explanations of the process from the barn, a local old-growth forest (Johnson Woods, see above), and the dendrochronology lab at Wooster.

lvargo022813Geology senior Lauren Vargo describes the value of tree rings for climate history, and is shown in several action shots of coring and sanding.

anash022813Andy Nash, another geology senior, describes the construction of “floating chronologies” from tree cores that are eventually tied to the larger dendrochronological record to give dates to the wood. (With an accuracy, as Greg likes to say, of “plus or minus zero years”.)

gwiles022813bBack in the lab, Greg shows how the cores from the Emerson barn are counted and measured with our video microscope system. On the monitor is a magnified view of rings from the Emerson barn.

nwiesenberg022813bNick had the honor of announcing the calculated date the trees were cut to make the barn’s beams: (Spoiler Alert!) the Fall of 1845. The ground would have been hard then and the farmers would have had time to collect materials for the construction.

It was great fun to see our students and colleagues explain their work so well, and to show the world the enthusiasm and professional skills of Wooster’s dendrochronologists.

The full “Barn Detectives” video is available on YouTube at this link.

Contemporary melting of northwestern glaciers: A new paper by Wooster Geologists … and the ultimate finish of an Independent Study adventure

January 25th, 2013

OLYMPUS DIGITAL CAMERAWooster geology graduate Nathan Malcomb, now a scientist with the Pacific Northwest Research Station of the U.S. Forest Service, has just published an important paper with his advisor Greg Wiles in the journal Quaternary Research (affectionately known as “QR”). This work comes directly from Nathan’s Independent Study research with Greg, a project that was supported by the Henry J. Copeland Fund for Independent Study at Wooster. (A view of their field area in Valdez, southern Alaska, is shown above.) This is one part of Greg’s very productive Alaskan research program with his students.

Nathan and Greg used tree-ring series from temperature- and moisture-sensitive trees to reconstruct annual mass balances for six glaciers in the Pacific Northwest and Alaska. They show strong evidence to support their hypothesis that the retreat of these glaciers we see today is a unique event in the last several centuries. This melting is “dominated by global climate forcing”. Recent climate change is again demonstrated by careful data collection and well designed tests.

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Sarah Appleton (’12) on one of the Alaskan coring expeditions.

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Lauren Vargo (’13) demonstrating excellent coring technique.

Reference:

Malcomb, N.L. and Wiles, G.C. 2013. Tree-ring-based reconstructions of North American glacier mass balance through the Little Ice Age — Contemporary warming transition. Quaternary Research (in press), http://dx.doi.org/10.1016/j.yqres.2012.11.005

Wooster Geologists on Camera — Spotlight on Dendrochronology

November 16th, 2012

WOOSTER, OHIO–Greg Wiles and members of his crack dendrochronology team from our tree-ring laboratory are being filmed today for a PBS program called “Our Ohio“. It is great fun watching the TV crew setting up their equipment, and our faculty, staff and students getting ready for their close-ups. We thought you might like to see a few pictures of the process. In the image above you see Greg thoughtfully listening to instructions from the field producer.

Here’s a closer view of the camera set-up, including a small monitor that shows exactly what the camera sees.

Jenn Horton (’13), looking stylish and Wooster-branded, is talking to the film crew as they set up the dendrochronology lab with lights. Tree-ring lab veterans know this room well! (I think it looks a little cleaner than usual.)

Greg Wiles and our ace technician Nick Wiesenberg at one of the dendrochronology stations prior to filming. Nick had just dated a particular barn in question as having been built in — spoiler alert! — 1845. A preliminary date, Greg quickly adds.

The TV crew van parked outside Scovel Hall this morning, greatly enhancing our departmental prestige on campus. (Everyone knows, after all, they didn’t come here to interview philosophers.)

We hope to have more photos later of the outdoor filming. Well done, Wooster dendrochronologists!

Wooster’s Fossil of the Week: Birch wood with beetle borings (Oligocene of Oregon)

November 4th, 2012

We may be at the Geological Society of America annual meeting today, but that doesn’t stop Fossil of the Week! This week’s fossil is a beautifully-detailed piece of petrified birch wood (Betula) with tree rings and insect borings throughout. It was found in the Little Butte Formation (Oligocene) of Linn County, Oregon. This rock unit consists of thick tuffs and volcanic breccias representing volcanic mudflows and nuée ardente deposits that buried diverse hardwood forests. This formation is known for its spectacular silicified fossil wood.
The beetle borings, shown in closer view above, are very similar to those bored in birch trees today. There is little work done on the ichnotaxonomy of these trace fossils, so I can’t yet give them a name, but at least we can see typical beetle activity in the twists and turns. The holes are apparently filled with a cemented mix of insect feces and wood fragments called frass, just like we find in modern birch wod today.

References:

Beaulieu, J.D., Hughes, P.W., and Mathiot, R.K. 1974. Environmental geology of western Linn County, Oregon. Oregon Department of Geology and Mineral Industries Bulletin, no. 84, 117 p.

Rozefelds, A.C. and De Baar, M. 1991. Silicified Kalotermitidae (Isoptera) frass in conifer wood from a mid-Tertiary rainforest in central Queensland, Australia. Lethaia 24: 439-442.

TREE CAMPUS USA – The College of Wooster

September 24th, 2012

On a beautiful homecoming afternoon in September – The College of Wooster celebrated its new designation as a Tree Campus USA. This special designation of The College of Wooster was lead by Beau Mastrine, director of grounds (above).  Partners include the City of Wooster and the OARDC. Grace Tompos, a good friend of the campus trees, places a shovel of dirt onto the latest maple planted in front of Holden Hall.
Andy Nash and Lauren Vargo of the Wooster Tree Ring Lab in Geology  explain the science of tree-rings as part of  the Tree Campus USA celebration. Both students will be using the campus tree-ring data in their drought studies and will be presenting their results at the annual meeting of the Geological Society of America Meeting in November. Andy’s work examines drought in the Midwest and Lauren’s study will analyze the link between North Pacific climate and Midwest drought.

Dr. Mariola (Environmental Studies) explains how he uses the campus trees in his courses. The tree journal assignment increases awareness of the practical and aesthetic value of the trees.

 

 

 

 

 

 

The D-shaped hole of the emerald ash borer (above). On the left is a “tree IV” (left) hooked up to a Green Ash on campus. This treatment repels the ash borer attack and protects the tree.

 

 

 

Employees of the City of Wooster explain the value and care of the urban forest.

Below is one of the bottom lines of the value of trees – here summarizing the value of the campus’ maples.

 

Wooster Tree Ring Lab Ready for Business

June 10th, 2011

Guest blogger Jon Theisen

Beginning May 17th and running until June 10th, the College of Wooster Tree Ring Lab has been partnering with and funded by The Center for Entrepreneurship in an effort to demonstrate the viability of dendrochronological dating as a business opportunity.   The professor in charge of the Tree Ring Lab, Greg Wiles, and his employees, Jon Theisen and Anna Mudd, have spent the last four weeks collecting and dating samples gathered from the towns of Worthington and Somerset, Ohio.  The first week of the project consisted of traveling to the towns of Worthington and Somerset, which are approximately two hours south of Wooster.

Greg Wiles and Jon Theisen consulting with Somerset Mayor Tom Johnson in the Ridenour Barn, one of the many structures sampled by the Wooster Tree Ring Lab

On Tuesday, May 17th, members of the Tree Ring Lab traveled to Worthington, Ohio, in order to sample two structures for the Worthington Historical Society.  The first structure was the Old Rectory, which the Tree Ring Lab successfully dated to 1846.  The Old Rectory was built to house the reverends of St. John’s Episcopal Church.

In the afternoon, members of the Tree Ring Lab went to the Orange Johnson House, just a quick drive from the Old Rectory, in order to gather tree ring samples.  The Orange Johnson House was successfully dated to 1811 for the original structure.

The next day, researchers traveled to Somerset, Ohio, to meet with the Mayor, Tom Johnson.  Mayor Johnson had a number of structures that he wanted dated, so the Tree Ring Lab got to work.

The front of the Miller Tavern in Somerset, Ohio.  Although the exterior of the building has been renovated, the interior beams of the building are still original.

The first building the team sampled in Somerset, Ohio, was the Miller Tavern.  The image above is of team member Jon Theisen using a hand auger to retrieve a wooden core sample from a wall beam in Miller Tavern.  The Miller Tavern was successfully calender dated to 1808.

The team spent Thursday, May 19th in the Tree Ring Lab becoming familiar with the equipment and computer programs they would use to date the cores retrieved from the structures we sampled.  Below is an image of what the retrieved cores look like after they have been sanded and mounted.

The retrieved cores are glued into wooden mounts, and then sanded with a belt sander and high grit sandpaper until they are very smooth and the individual rings can be seen under the microscope.  The cores are counted and the total number of years represented by individual rings is written on the side of the mount.  After the initial count is completed, the cores are placed on the Acu-Rite measuring system, and by using a computer program called Measure J2X, the width of the individual tree rings is measured to the nearest 0.001mm.  These measurements are saved to a computer file where they can then be edited.  A computer program called COFECHA is then used to compare the ring width data of cores taken from a single structure against each other to create a “floating” chronology where the cores are relatively dated against one another.

An example of how cores can be dated relative to each other in order to develop a “floating” chronology

Once a “floating” chronology has been developed for a structure, the ring width measurements are compared against a calendar dated master series of measurements that have been previously dated.  By comparing the “floating” chronology against the master series, a calendar date can be assigned to the structure.

After a day in the lab, the team was ready to get back out in the field and continue gathering samples.  Friday, May 20th saw members of the Tree Ring Lab return to Somerset, Ohio, to gather samples from more structures off of Mayor Tom Johnson’s list.  In the morning the team stopped at the Linnabary House, pictured below, to take a sample.  According to the owners, the house was originally used as a church.  The beam was successfully dated to 1823.

In the afternoon, the team collected samples from two structures.  The first building was the historic library of Somerset, which was still in use today.  The team went down to the basement of the library, pictured below, and gathered samples from the joists supporting the floor.  The library was successfully dated to 1818.

After the library, the team traveled into the country and visited the Johnson House, pictured below.  While the building had been damaged by recent storms that downed trees, Tom Johnson is hoping that a date for when the structure was built will help secure funds for rehabilitating the structure.  The Johnson House was calendar dated to 1817.

 

After the first week in the field, the team spent the following three weeks in the Tree Ring Lab sanding, counting, and dating cores.  During this time, Jon Theisen and Anna Mudd created seven reports detailing the findings for each structure, a poster, and a blog post.  The reports consist of the name of the structure, a description of the dating techniques used, the calendar date of the samples, and a graph showing how well the measured samples correlate with the master series they were dated against.

These four weeks have shown members of the Tree Ring Lab that there is a great demand for dendrochronological dating.  Dr. Wiles has continued to receive requests for the Tree Ring Lab to visit sites across Ohio in order to gather samples and provide dates for historic structures.

Tree Rings and the Huna Tlingit People: A Wooster Student Geologist Talk

October 31st, 2010

Sarah Appleton ('12) presenting her research at the 2010 GSA meeting.

DENVER, COLORADO — The Wooster Geologists are very proud today of our own Sarah Appleton, who just gave a professional talk at the Geological Society of America Annual Meeting this morning.  Her topic was sorting out a historical mystery about Eighteenth-Century migrations of the Tlingit in Glacier Bay, Alaska. Sarah did a superb job.  This is the first time in my memory that one of our junior geology majors gave a national talk.  Well done, Sarah.  (And now I have to prepare for my own talk!)

Wooster Geologist = NPR Star

September 10th, 2009

Tree rings, Lake Erie, and climate change are the topics of a recent NPR interview with Wooster’s own Greg Wiles. Greg and his research group have been making headlines for their study that suggests natural climate variability plays a role in controlling changes in Lake Erie’s level. Stay tuned for more developments from Wooster’s Tree Ring Lab!

From the Guardian, May 14, 2009 issue.

From the Guardian, May 14, 2009 issue.

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