Hello Raoul,
Google Earth will greatly enhance your research and will help you locate sites from long ago, Here's an area that has taken me 18 years to locate. With Google Earth, it only took several hours of scanning the miles of open range with rolling hills.
This particular trail and area dates back to the Indians, A year round water source and then used by the Spanish explorers, the fur trappers and famous men such as Kit Carson and others, Then the Stage route used this trail and many travelers as well, Two centuries from 1700 to late 1800's used this route and watering hole.
I once made an attempt 18 years ago by foot to locate this area and due to the harsh surroundings and rolling hills, I couldn't locate the site. Now, I'm working with getting permission from the property owner to enter this old ground, Already have permission from two other property owners leading to this area and now just need permission from the owner that own this area.
The dirt road in the picture is the actual trail used back then, Now cattle freely wonder here from the miles of rolling hills. One can only image the abundance of finds to be made here. Centuries of relics and maybe coins dropped by the Indians, the Spanish, Stage route finds, French fur trappers and famous explorers alike. A place well hidden out in no mans county.
God luck with your research,
HH, Paul (Ca)