I believe this is the San Miguel Mountain near National City (San Diego County Ca.)
doing a quick search of newspaperarchive uisng google (pay per read so I didn't read)
turned up these possible references (key words were San Miguel ancient)
Evening Democrat (Newspaper) Septmeber 16 1895
Sweet water dam and along the North Slopes of San Miguel Mountain
Cooke of San Diego
Newark daily advocate (ohio newspaper) September 7 1895
...along the north slopes of San Miguel Mountain...
ancient make believed to be mining tools
stevens point journal (newspaper) october 5 1895
the conclusion is that this is an ancient and rich mine.
stevens point Journal (newspaper) November 16 1895
San Miguel mountain by Herman C. Cook and ..
San Miguel is a town located about ten miles north of Paso Robles on Rt. 101. Here's some history of the area:
Since prehistoric times, people have lived in the area that now surrounds the Mission and the town of San Miguel. The Franciscan Padre, Fermin Francisco de Lasuen (who was the successor of Padre Junipero Serra) founded Mission San Miguel on July 25, 1797. It was named for the "Most Glorious Prince of the Celestial Militia, Archangel Saint Michael."
In 1806, twenty-seven huts were constructed, to be used as living quarters for the local Indians. During the year 1810, thousands of adobe bricks were made and stored; they were to be used in the construction of the present church. In 1816, the stone foundations for the church were put in place.
Here's another San Miguel--referring this time to the mountains: "Chula Vista means "beautiful view" and is nestled around a bay filled with boats, with the picturesque San Miguel Mountains as the backdrop." Chula Vista is near the Mexican border, San Diego County.
Here's a 1950 map of the area--and mountain site (located between Sweetwater Res. and Lower Otay Res.)
The mountain was used as a repeater station for HAM operators; now probably used for higher tech applications. Heck, it may be condo heaven there. Nearly 60 years will change most landscapes, especially in So. Cal. http://history.sandiego.edu/gen/maps/sd/1950sandiegoTbg.jpg
Jeff:
I went to San Miguel mountain two days before the recent fires started in So.Cal. I found most of the mountain access blocked by a gate with plenty of "No
Tresspassing" signs. The flat areas are now taken over by emu, ostrich or sheep farms and expensive housing. If the housing foundations mentioned in that news article were there, my guess is they are now under modern structures--or at least on private properties. Current aerials of the area show no signs of the past--at least to my old eyes--but the trip there and a couple of cold ones with the locals to learn more made the day a great adventure.
Don........