Paleoclimate - Spring 2019
Cedar Creek Mastodon Site – Radiocarbon Analysis (courtesy of Beta Analytic Inc.)
Wood sample extracted by Emily, Sarah and Tom. Accelerator mass spectrometer dating of the sample yielded the age below.
What does the timing of this transition tell us about climate change in Ohio at this time? Is this interval relevant to the Mastodon excavation?
The Wooster Geology Climate Change class spent a beautiful fall day in Stony Creek, Ohio coring beams in three structures of historical significance. They will determine the cut dates (calendar dates when the timber for the houses were felled) for the homeowners and then examine the tree-ring data that results to help reconstruct drought for the region. The class will write a report for the homeowner as part of the project. The Wooster tree-ring lab has dated over 50 buildings. Many of the reports are archived here.
Willy coring a hand hewn beam with an increment borer in the basement of one of the structures.
Dan cores into the white oak beam as Meredith keeps the utilities at bay.
Julia identifies the outer (bark year) rings of a large oak beam and sets the spoon to extract the core.
Meredith and Haley team up to extract another core from a structure.
Zach shows how the 5 mm core is mounted in a slotted core mount.
Sarah glues the carefully oriented core into the mount.
Orienting the core properly is crucial for the next step of sanding the surface.
The group should be able to determine when the timber was cut to build this restored structure. Sometime in early November the analyses should be completed.
Some extracurricular coring of young white pines in the area.
Picking seeds from a critical layer of mud – the seeds will be sent out for radiocarbon analysis.
An important step was photographing the cores.
Some of the smear slides required a petrologic scope to see the fine-grained sediments.
Identification of wood from the core below will backer the age of the marl the class plans to analyze for stable isotopes.
Marl section a piece of wood was recovered from the hole in this core. 
Interesting feature at the top of one of the thrusts – determined to be an artifact of coring.
At the end of the lab period two regions were picked for organic material that will be sent into Beta Analytic for radiocarbon dating.
Our Climate Change class visited Browns Lake Bog with the Plant Communities and Ecosystems class from Ohio Weslyan University’s Biology class taught by Dr. Laurie Anderson. Dr. Chuck Goss, a stream ecologist from the OARDC also joined us. Both Laurie and Chuck offered new insights (and measurements) for us to consider.
One of the themes we discussed is how an influx of dust with land use change during European Settlement about 200 years ago may have “fertilized” the low nutrient bog and may have forced (is still forcing) plant communities in the bog to change. An additional challenge of to think about how the natural succession of the bog and disturbance contribute to observed changes.
Sediment cores (on the tailgate) are being looked at with the thought of lithologic and plant community changes potentially being caused by clearing of the land and increased dust flux.
Instrument that measure soil moisture – from the wet groundwater fed bog areas to the drought-sensitive forests.
Dr. Goss explains the various measurements taken in the water column beneath the floating bog and the class puzzles over how this may be reflected in the lake cores we are analyzing in the lab.
Sphagnum moss and a few Sundew plants. The moss is a primary component of the peat in our cores and the Sundew is another of the carnivorous plants that grow in the low nutrient environment of the bog.
Pitcher plants – digesting insects, nice adaptation to a low nutrient environment.
Assistant Directors of the Tree Ring Lab, Willy and Zach provide instruction on how to core a white oak to the eager group.
Two folks in the group seemed to catch on (but this is an elm…).
Back on track with a mighty oak – Tom takes a turn.
We also wondered why the tree-ring width chronology from Browns Lake (above) maintains a 2-3 fold increase in growth after clearing of the land in the early 1800s. Is it because of changes in competition, carbon dioxide, nitrogen, dust, precipitation or some combination of all these. Seems to be a story in the lake and tree cores – will take some work to sort it out.
Tom Lowell and graduate student Stephanie Allard from Cincinnati and Jacqueline Rodriguez from the University of Illinois made the trip to Morrow County to core mud from a bog adjacent to the Cedar Creek Mastodon site. We will be working with the cores over the next several weeks. 
The base of the lake and is an organic ooze with some loess and is transitional from the Ice Age to The Holocene.
Saturday is the Coring of the Cedar Creek Mastodon Site with Dr. Lowell (University of Cincinnati) and Jacklyn Rodriguez (University of Illinois). Tom Lowell truly is the Core Boss and is remarkable when it comes to extracting high quality mud from the ground.
Tom Lowell – extracting high quality mud from the bottom of a lake.
Monday we will meet with Drs. Anderson (OWU) and Goss (OARDC) at Browns Lake Bog – we will be taking a short core from around the big lake and discussing various aspects of the science of the bog. Below is a synopsis of articles (thanks Tom and Laurie) that are pertinent to the Browns Lake trip (access to the readings are on the reading page).
Sanger and Crowl 1979 – used plant pigments – It is simple property to measure, but you had better refer to the paper for what it means. The first part of the paper is a bit heavy on biological terms, but there some interesting discussion of the changes that occurred as the lake evolved. Figure 2 gives us a decent view of the general changes we should find as we core deeper into the stratigraphy.
Shane 1987 – used pollen to contrast past environmental changes at high elevations and low elevations. The pollen assemblies change over time and the assemblies (pollen zones) and they are placed in some chronological order. Such a study today would have far more detail (samples per physical level) and more ages to generate the zones. Browns lake is only one of several sites studied for this. The raw data for Brown’s lake is in Fig 2.
Lutz 2007 – is a physical description for one event in the early Holocene, the so-called 8.2-ka event. A preliminary depth map (in feet) is shown in fig 1. You can see the bottom is flat and that reflects sediment accumulating in the bottom of the basin. Note this study took 3 cores in different parts of the lake, but only a very small part of the whole core is shown in Fig 2. In one core, 3, there are two distinct silt layers that are interpreted as wind blown silt formed during dry conditions (the 8.2 event).
Shane 1993 – is a follow up of the 1987 paper by adding more sites and then applying a transfer function (calibration) to extract more quantitative estimate of temperature and precipitation. Lots of detail in this and it is a bit thick. Data from Browns Lake is included in the analysis, but it is not identified specifically. This is a general framework for climate changes over the last 18000 yr.
Glover, 2011 – takes a different approach. It also is a regional view, but for deglaciation or when the basins formed. There is only limited analysis of what happened after that. Again Browns Lake is included but it is only one of many. The take home from this paper is that the ice sheet left the Ohio region about 18,000 yr ago showing that Brown Lake is similar to other lakes.
Irleland and Booth 2012 – Described the influence of anthropogenic disturbance to bog sites and the cascading ecosystem responses. Remarkable – we can see this strongly in the short cores at BBL.
