According to Public Employees for Environmental Responsibility (PEER), the Park Service has been told to avoid offending fundamentalists and not mention what SCIENCE says about the age of the Canyon(Hint: It's more than 6,000 years old). Worse yet a 2002 memo providing guidelines to park interpreters and rangers for dealing with science versus religion has been suppressed.
Worse yet from a social point of view is this report from the PEER web site:
"In a series of recent decisions, the National Park Service has approved the display of religious symbols and Bible verses, as well as the sale of creationist books giving a biblical explanation for the Grand Canyon and other natural wonders.
These moves all emanate from top Park Service political appointees over the objections of park superintendents, agency lawyers and scientists. A number of fundamentalist Christian and socially conservative groups are claiming credit for these actions and touting their new direct and personal access to Bush Administration officials."
There is a link to a petition to fight this sort of mixing of government and religion so please hop on over to the petition site and sign on. The site also has a way to pass on an e-mail message to your friends to alert them to this as well.
By the way you cannot find information on the Geology of the Grand Canyon on the National Park Service's Grand Canyon site...unless you search the archives. Then you can find this link. Look quickly before it too is suppressed.
Update! See an alternate view and my response here.