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Probing the Jemez: Revived symposium features Valles Caldera studies

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By Roger Snodgrass

SANTA FE – After a four-year hiatus, the lightning round known as the Jemez Mountains Science Symposium returned Friday in a brain-pounding, mind-nourishing flash.Over the course of eight hours, the schedule called for 36 10-minute technical reports on aspects of geology, hydrology, ecology, biology, air and water quality, climate change, fire-history, controlled burns and land management.Fraser Goff, a retired earth scientist from Los Alamos National Laboratory, led off the encapsulated presentations with a preview of a revised geologic map of the Valles Caldera that he and many others have been working on since 2000.“The plan is eventually to have a new map of the Jemez Mountains,” he said.Displayed in a bright color-coded scheme in shaded relief, the map tells the geological saga of the central volcanic field of the Jemez Mountains with an emphasis on the last 1.25 million years. Many new details of pre- and post-Caldera features, including uplifts, lava flows and lake deposits are now visible.Goff matched and unified nine individually mapped quadrangles of the Valles Caldera, now rendered at a more highly resolved scale of 1:24,000, in order to pull the picture together.The map is still in preparation with a number of decisions yet to be made. Goff said a version will be published by the New Mexico Bureau of Geology and Mineral Resources, at New Mexico Tech in Socorro within the year.As a comprehensive image of the basic physical foundation of the Valles Caldera, Goff said, the map would be useful for land-use planning and as a tool for studying soil, water and many other natural resources.More than 60 people, many of them presenters, shared findings and questions during the symposium, mostly focused on the Valles Caldera National Preserve.An 89,000-acre piece of public land located 20 miles west of Los Alamos, the preserve has been the subject of intensive research in recent years under a management plan based on scientific principles.Bob Parmenter, preserve scientist, organized the event and was a collaborator on a number of the projects.“I talked to Craig Allen (of the U.S. Geological Survey) Steve Fettig (at Bandelier National Monument) and Joe Wargo (of the Forest Service) and asked if we should do this again,” Parmenter said. “They said yes. It’s been four years and there is a huge backlog.”Parmenter said the program filled up quickly and he expected it to become an annual event again.A big section of the morning program consisted of results from a controlled-burn experiment at the preserve November 2005. Another block of reports in the afternoon took up issues related to the elk herd that is a central feature of the preserve’s wildlife.Parmenter said the bottom line on the controlled burn was that it had minimal impact. The carefully scripted and supervised two-day fire in the Valle Toledo was studied from multiple angles, Parmenter said, so just about any typical question about the fire’s effects could be answered.He said there were some good and bad effects related to fire, but there was no increase in soil erosion or permanent harm to the flora.Individual studies covered such topics as the responses of soils, plants, fish and land and water bugs in burned and unburned, grazed and ungrazed areas of both grassland and forest.“Fire is a natural part of the ecosystem,” Parmenter said. “Species have co-evolved with fire.”Another experiment offered information to archeologists on the effect of fire on obsidian artifacts, which will add certainty to dating technique based on a rind that builds up over time on an obsidian stone.“There were a lot of positive, short-term effects and nothing detrimental to the soils or water quality,” Parmenter said. “We can safely continue.”The meeting was held at Santa Fe Community College. Abstracts of the presentations should be available on the preserve’s website shortly.