Kurt, I think Salt Dome Theory has some geologic momentum in that a lot of valleys in Utah were created by salt erosion. I like the meteor theory in that it does bring to the forefront the reality of meteor impacts in our future. Close up it is hard to visualize impact features, but it is one of my favorite places in Utah. Erik --- canopus56@yahoo.com wrote: From: Canopus56 <canopus56@yahoo.com> To: Utah Astronomy List Serv <utah-astronomy@mailman.xmission.com> Subject: Re: [Utah-astronomy] More on Upheaval Dome Date: Tue, 27 Jan 2009 13:57:34 -0800 (PST) Chuck wrote: "[B]ut the Observer's Handbook has for years listed the most significant impact craters in North America and Upheaval Dome has been on there for a while." The RASC list is from the Earth Impact database at: http://www.unb.ca/passc/ImpactDatabase/index.html While the list titled "confirmed impacts", an entry is based on subjective evaluation of six factors listed at the bottom of the page by one researcher - who is generally accepted as authoritative.  Notwithstanding the PASSC's earliest "pro-impact" rating in its list, geologic journal literature continued to dispute that it was an impact and present the classification as a disputed matter, e.g. our own Utah Geological Association in 2000: "The origin of Upheaval Dome has been the subject of speculation in a long, highly conflicting series of academic and popular articles. Only the most substantive or exotic are cited below. The field seems to have narrowed lately to salt diapirism (doming caused by flowage of buried salt) and impact; but this is not simply a debate about different processes, rather it reflects deeper philosophical divisions." Peter W. Huntoon. Upheaval Dome, Canyonlands, Utah: Strain Indicators that Reveal an Impact Origin. 2000 Utah Geological Association Publication 28 http://www.utahgeology.org/pub28_pdf_files/UpheavalDome.pdf And currently in 2009 at our National Park Service Canyonlands website: "What caused these folds at Upheaval Dome? Geologists do not know for sure, but there are two main theories which are hotly debated. Salt Dome Theory. A thick layer of salt, formed by the evaporation of ancient landlocked seas, underlies much of southeastern Utah and Canyonlands National Park. . . . Impact Crater Theory. When meteorites collide with the earth, they leave impact craters like the well-known one in Arizona. Some geologists estimate that roughly 60 million years ago, a meteorite with a diameter of approximately one-third of a mile hit at what is now the Upheaval Dome." http://www.nps.gov/cany/naturescience/upheavaldome.htm Only PASSC criteria no. 2 is considered conclusive, irrefutable evidence of an impact by geologists: "Presence of multiple planar deformation features (PDFs) in minerals within in situ lithologies (microscopic evidence)." PDFs cannot be formed by known terresterial forces.  They can only be formed by impacts.  That is what Kenkmann brought to the table in March 2008 - He found the PDFs at Upheaval.  Other researchers, including Kenkmann himself on his first try, failed to find definitive PDFs at the center of the impact site.  He thought to look in the outer ring and found the PDFs there. Like you, Chuck, I am a long-time impact crater theory believer. But the science wasn't there until the PDFs were found last March. If there is anything I've heard from people over the years who are up on the issue and who have been to look at the Dome, it's "when can we get the Park Service to fix that stupid sign!" that they put up in the early 1990s at the south viewing area. The sign is still there. http://www.seismo.unr.edu/ftp/pub/louie/dome/plaque-dome.GIF http://www.seismo.unr.edu/ftp/pub/louie/dome/plaque-meteor.GIF Clear Skies - Kurt _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://gallery.utahastronomy.com Visit the Wiki: http://www.utahastronomy.com