By Scott Thybony
http://stream.publicbroadcasting.net/production/mp3/knau/local-knau-987148.mp3
Flagstaff, AZ – Years of erosion have threatened to destroy nine prehistoric sites in the Grand Canyon. As a last resort, archaeologists undertook the most extensive riverside excavation in 40 years. Commentator Scott Thybony has followed their efforts for the past few years and wanted to find out more.