I can not remember the name of the book or the main character but I do remember a lot about the book itself. Firstly there is a canyon or valley that can only be accessed through something like shale slides. In one part of the story the female character is curious where the main character lives and she gets there at night and he has to direct her across the shale slide( it may be sand too). Also the main character previously had a best friend who I believe is a Texan but they don’t talk because the Texans sister was murdered in Louisiana and the Texan thinks the main character did it. Only it turns out that the man who did do it is the rancher heading up the whole rustling operation. The last big thing I remember is that the Texan was going to be drygulched but the main character stopped it. The drygulcher was using a Buffalo gun at a long range and he had studied the Texan and knew all his routine habits, even down to which way he mounted his horse. I hope this helps and that you can help me with this.