Category: History - American
The mining industry in this county is not as extensive as that of some of the neighboring counties, but there are mines in Los Angeles County of unquestioned value, and others which have a prospective value, dependent to a great extent upon the success achieved in working cert...
On the San Jacinto estate, which is owned by an English syndicate, are located the old Gavilan Mines, which years ago produced from quartz veins considerable gold, the rock bein...
12. Part 12A few miles to the northwest from Julian is located the Mesa Grande District, where lenses of a yellowish pellucid quartz of semi-granular texture have been developed somewhat....
6. Part 6A long, high ridge running northwest and southeast, adjoining the lava, is very interesting. It is about 200 feet higher, and covered with dense brush, as is all the country in...
10. Part 10In the vicinity of the mines described in this district are numerous other claims, some of them having considerable development, but all lying idle at the time of my visit. One...
9. Part 9Of several thin sections made for the purpose of microscopic study of these rocks, their behavior under the microscope is so similar that general description will suffice for al...
7. Part 7At the time of my visit the mine had been opened to a depth of 180 feet, by two working shafts. The total length opened on the vein is 300 feet. Two levels have been run and wor...
2. Part 2At the north end of Jacumba Valley, and on the west side of the outlet, is an area of volcanic rock, probably basalt. It forms a table-land, gently sloping toward the valley, an...
5. Part 5The Tertiary beds north of the Santa Margarita Creek are very different in outline from those south. Instead of their extending in a gradual slope from the older mountains to th...
1. Part 1The mining industry in this county is not as extensive as that of some of the neighboring counties, but there are mines in Los Angeles County of unquestioned value, and others w...
3. Part 3The crystalline rocks exposed between the Sweetwater and El Cajon Valley generally show more of a dioritic composition than granitic. They have a glassy feldspar, much hornblend...
4. Part 4The first outcrop of crystalline rocks in Mission Valley is about 3 miles above the old Mission, where the San Diego River enters a cañon. It is a volcanic tufa, consisting of g...
8. Part 8The formation of the ore deposits in the Calico District has been a subject of much discussion, and the question has received the closest study and thorough investigation. In my...
13. Part 13The velocity of a river current varies with the seasons on account of the different volumes of water carried, but it also varies at different points of the river, during the dif...