Dr. Joanne BallardJoanne has a PhD in Geography from the University of Tennessee with specializations in Biogeography and Quaternary Environments, advised by Dr Sally Horn, palynologist.  She has a M.S. in Geology from the University of Cincinnati, studying under glaciologist Dr. Thomas Lowell.  She has also worked as an Archaeologist for the Tennessee Valley Authority as a Database Analyst and Mapping expert.  In addition, Joanne worked for the US Census Bureau as an Analyst and Cartographic Technician, giving technical support, troubleshooting, and training personnel on addressing projects.  Currently, Joanne is serving as a Naturalist at a local museum, and working with Czech colleagues on YDB research led by Dr. Evzen Stuchlik at the Czech Academy of the Sciences.  Joanne is a catastrophist, and collaborates with the Comet Research Group.Joanne has been intrigued with the causation for the megafauna extinction since the 1990s.  She met Rick Firestone at the Mammoth Conference in 2005 at Hot Springs, SD.  When he and others presented their hypothesis on a bolide strike as causation for the Younger Dryas onset (Firestone et al. 2007), she wanted to look for evidence. Lake mud contains various proxies that help us gain insights into past environments, such as charcoal (wildfires), pollen and macrofossils (vegetation), diatoms, chironomids (climate) and chemistry--isotopes and elements. Lake mud is considered less disturbed (such as by roots, earthworms, freeze/thaw) than terrestrial sediment or soil.  At UC, she and her team drilled through the ice to collect cores from four lakes near Flint, Michigan, two of which (Slack and Swift Lakes) are adjacent to the Gainey archaeological site mentioned by Firestone et al. (2007).  At UT, she studied lake sediments from sites in the southeastern USA.   She discovered a new proxy for wildfires--possibly catastrophic wildfires--which are siliceous aggregates. These form in wood ash.  After a tree burns to ash, the silica phytoliths that were part of the structure of the tree are deposited with the wood ash. When that highly alkaline ash gets wet, it causes the phytoliths to dissolve, and the silica gel percolates down through the ash and then hardens up around silt or other particles in the sediment.  Five of six lakes sampled across eastern North America showed siliceous aggregates around the time of the onset of the Younger Dryas, suggesting widespread, catastrophic wildfires.  However, more work needs to be done to support this interpretation.Joanne has also researched Usselo Horizon sites (typically YDB-age black mats) in The Netherlands and Belgium to understand the events that triggered the onset of the Younger Dryas (12,900 - 11,600 BP).  At four Usselo horizon sites across the NL and BE, she found fused quartz, soot, charcoal, melt glass and sponge spicules.See her PPT presentation "Usselo Horizon Presentation" here:https://www.researchgate.net/profile/Joanne-Ballard/researchDid humans tame woolly mammoths?  See the discussion here with 821 postshttps://www.researchgate.net/topicshttps://www.researchgate.net/post/Did-humans-tame-woolly-mammoths-or-other-megafaunaJoanne's dissertation can be accessed and downloaded for free here:https://trace.tennessee.edu/utk_graddiss/3492/Evidence of Late Quaternary Fires from Charcoal and Siliceous Aggregates in Lake Sediments in the Eastern U.S.A.Her MS thesis can be accessed for free here: https://etd.ohiolink.edu/acprod/odb_etd/etd/r/1501/10?clear=10&p10_accession_num=ucin1250268463A Lateglacial Paleofire Record for East-central MichiganRick Firestone's paper:https://www.pnas.org/doi/10.1073/pnas.0706977104    Evidence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions and the Younger Dryas cooling-- Sent with Tuta; enjoy secure & ad-free emails: https://tuta.comBecome a supporter of this podcast: https://www.spreaker.com/podcast/earth-ancients--2790919/support.