It hit me now - this Bonanza map is totally wrong! The location of Reno is OK, but Carson City is east (kind of south east) of lake Tahoe and Virginia City is even more east of Carson City.
Virginia City is actually in the dessert, unlike in the serial. The serial was filmed in forested areas of California.
Yep.... the compass is a dead giveaway.
The map is pretty much right on the money. Note that the compass rose shows east as up.