Here are a few links to the geological and cultural history of the Green river and surrounding area of Canyonlands:

http://utahtrails.com/AndersonBottom.html

http://www.travelwest.net/parks/canyonlands/history.html

http://www.nps.gov/cany/nature/geology/index.htm

http://www.nps.gov/cany/pdfs/ (PDF)