Book about Glen Canyon before/just as it was flooded by a dam. There were two boys, teen/preteen, Anasazi ruins, mystery involving murder/looting of ruins/ecologists (?). Pre-1975 publication date, I seem to remember a green hard cover w/ gold or white print.
I believe the book you are looking for is The Mystery of the Lost Cliff Dwelling by Gordon D. Shirreffs, Prentice-Hall, 1968.
I think you’re right. Thank you!