Revision History for USGS 
  Scientific Investigations Map 3144

  Ken Walsh, Gary L. Peterson, Marvin H. Beeson, Ray E. 
  Wells, Robert J. Fleck, Russell C. Evarts, Alison Duvall, 
  Richard J. Blakely, and Scott Burns

  A Tunnel Runs Through It--An Inside View of the Tualatin 
  Mountains, Oregon

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  unit Qbsh polygon on the map that is labeled Qbsh but was 
  not Qbsh color
  July 29, 2011

  Posted online at http://pubs.usgs.gov/sim/3144/
  March 29, 2011

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