Project Title

Pliocene Wood from the Gray Fossil Site

Authors' Affiliations

Owen Fredric Madsen, Department of Geosciences, College of Arts and Sciences, East Tennessee State University, Johnson City, TN. Dr. Chris Widga, Department of Geosciences, College of Arts and Sciences, East Tennessee State University, Johnson City, TN.

Location

Culp Room 210

Start Date

4-6-2022 11:45 AM

End Date

4-6-2022 12:00 PM

Faculty Sponsor’s Department

Geosciences

Name of Project's Faculty Sponsor

Chris Widga

Classification of First Author

Undergraduate Student

Competition Type

Non-Competitive

Type

Boland Symposium

Project's Category

Climate Change

Abstract or Artist's Statement

The Gray Fossil Site in northeastern Tennessee preserves materials from a 5-million-year-old ecosystem, including wood from nearby trees. Trees provide a unique perspective into ecosystems as they are immobile during their lifetime. As such, tree rings convey information about precipitation and temperature for a given location. As southern Appalachia is one of North America’s most biodiverse regions, and modern climates are warming, understanding the warmer past climate of the Gray Fossil Site can help predict the region’s future. This study consists of three parts: conservation of wood remains, identification of taxonomic groups represented by the fossil wood, and the measured organic content of fossil wood from the Gray Fossil Site. When excavated, the wood is saturated due to a modern local high water table. A variety of drying methods from paleontology, archaeology, and dendrology were compared on saturated samples, from string wrapping to refrigeration, alcohol replacement to microwaving. The method least likely to cause warping and cracking is to wrap specimens in cotton string to slow drying. Microscopic examination of the wood reveals tree rings that have identifying features. Utilizing identification keys for tree rings, each specimen with visible rings can be identified. Taxa represented by fossil wood specimens are like those present in pre-modern forests. Finally, loss on ignition tests reveal that the Gray Fossil Site wood lacks extensive permineralization or mineral replacement. As the wood is 80-90% organic, alpha-cellulose can be extracted. The presence of alpha-cellulose, albeit stained with iron oxides, indicates that future stable isotope analyses are possible.

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Apr 6th, 11:45 AM Apr 6th, 12:00 PM

Pliocene Wood from the Gray Fossil Site

Culp Room 210

The Gray Fossil Site in northeastern Tennessee preserves materials from a 5-million-year-old ecosystem, including wood from nearby trees. Trees provide a unique perspective into ecosystems as they are immobile during their lifetime. As such, tree rings convey information about precipitation and temperature for a given location. As southern Appalachia is one of North America’s most biodiverse regions, and modern climates are warming, understanding the warmer past climate of the Gray Fossil Site can help predict the region’s future. This study consists of three parts: conservation of wood remains, identification of taxonomic groups represented by the fossil wood, and the measured organic content of fossil wood from the Gray Fossil Site. When excavated, the wood is saturated due to a modern local high water table. A variety of drying methods from paleontology, archaeology, and dendrology were compared on saturated samples, from string wrapping to refrigeration, alcohol replacement to microwaving. The method least likely to cause warping and cracking is to wrap specimens in cotton string to slow drying. Microscopic examination of the wood reveals tree rings that have identifying features. Utilizing identification keys for tree rings, each specimen with visible rings can be identified. Taxa represented by fossil wood specimens are like those present in pre-modern forests. Finally, loss on ignition tests reveal that the Gray Fossil Site wood lacks extensive permineralization or mineral replacement. As the wood is 80-90% organic, alpha-cellulose can be extracted. The presence of alpha-cellulose, albeit stained with iron oxides, indicates that future stable isotope analyses are possible.