What is an example of the author's use of ethos in The Damnation of a Canyon?

In "The Damnation of a Canyon," the author uses ethos by drawing on his experience as a naturalist and advocate for preserving wilderness areas to establish credibility and expertise on the subject of damming the Glen Canyon. By sharing his personal connection to the landscape and his knowledge of its ecological importance, he creates trust with the reader and enhances the persuasive power of his argument against the dam project.