Jack C. Ridge
Department of Geology
Medford, MA 02155
Professor of Geology
My research focuses on formulating chronologies for Pleistocene glacial/climatic events in the northeastern U.S. The main goal is the creation, consolidation, and calibration of varve chronologies from glacial lake deposits through outcrop and drill core sampling, radiocarbon age determinations, and paleomagnetism. Varve (annual sediment layer) chronologies from Pleistocene glacial lakes in the Northeast allow us to determine a detailed deglacial chronology and glacial process rates for events of the last ice age. Glacial varve thickness is related to glacial meltwater production and can be used to formulate climate records for very abrupt climate oscillations that influenced deglacial melting rates. Varve chronology has also been used to reconstruct the reinhabitation of fish and other organisms in New England waterways, place constraints on the first occupation of the landscape by humans, and calibrate ice age cosmogenic radionuclide (10Be) dating. I currently maintain an NSF-funded web site, the "North American Glacial Varve Project" that acts as a repository for glacial varve information, techniques, and data (see http://ase.tufts.edu/geology/varves/).
Balco, G., Briner, J., Finkel, R.C., Rayburn, J., Ridge, J.C., and Schaefer, J.M. 2009 Regional Beryllium-10 Production Rate Calibration for Late-glacial Northeastern North America. Quaternary Science Reviews 4: 93-107. doi:10.1016/j.quageo.2008.09.001
Benner, J.S., Ridge, J.C., and Knecht, R.J. 2009 Timing of Post-glacial Reinhabitation and Ecological Development of Two New England, USA, Drainages Based on Trace Fossil Evidence. Palaeogeography, Palaeoclimatology, Palaeoecology 272: 212-231. Doi:10.1016/j.palaeo.2008.10.029
2004 The Quaternary Glaciation of Western New England with Correlations to Surrounding Areas. In Quaternary Glaciations — Extent and Chronology. Part II: North America, J.Ehlers and P.L. Gibbard, (Eds.), pp. 212-231. Developments in Quaternary Science, vol. 2b. Amsterdam: Elsevier.
2003 The Last Deglaciation of the Northeastern United States: A Combined Varve, Paleomagnetic, and Calibrated 14C Chronology. In Geoarchaeology of Landscapes in the Glaciated Northeast U.S., J.P. Hart and D.L. Cremeens (Eds.), pp. 15-45. New York State Museum Bulletin 497.