scott thybony http://knau.org en Commentator Scott Thybony Shares Some Rules Of The Grand Canyon http://knau.org/post/commentator-scott-thybony-shares-some-rules-grand-canyon <p>Rules of thumb come in handy at times.&nbsp; Commentator Scott Thybony has learned a few of them over the years from Grand Canyon guides, scientists, and rangers. Fri, 14 Sep 2012 11:00:00 +0000 Scott Thybony 20228 at http://knau.org Commentator Scott Thybony Shares Some Rules Of The Grand Canyon