Zane Grey 
Wanderer of the Wasteland [EPUB ebook] 

Adam Laret, big, young and headstrong, ran from Ehrenberg to the banks of the Rio Colorado. He was blindly fleeing his scheming, gambling brother and the woman Guerd stole from him. But Adam’s escape wasn’t complete until Guerd, in the company of a sheriff, hunted him down. Then Adam committed the ultimate crime. With the mark of Cain upon him–he traveled into the desert to atone for his sins.