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GEOLOGIC GUIDEBOOK ALONG HIGHWAY 49 



[Bull. 141 



than the mines below Amador City and are much less extensive. Produc- 

 tion has been intermittent and unspectacular. 



A mile farther north, Highway 49 crosses the Cosumnes River and 

 Amador-El Dorado County line. The Cosumnes branches into two forks 

 just above this spot, the South Fork cutting immediately across the ridge 

 to the east and the North Fork flowing north for several miles parallel 

 to the highway. West of the Cosumnes River bridge, also known as Huse 

 Bridge, the river flows in a deep canyon cut through Logtown Ridge. 

 A hike of a few miles down this canyon is well worth the geologist's time. 

 Along the stream bed are exposed type sections of two members of the 

 Amador group, the Logtown Ridge meta-andesite agglomerate and the 

 Cosumnes meta-sediments composed of conglomeratic, sandy, and tuffa- 

 ceous beds. 



Two miles north of the Cosumnes River bridge is the old mining camp 

 of Nashville or Quartzburg. The site of Nashville was originally an old 

 Indian camping spot or rancheria, and the mining camp was one of the 

 first lode camps in the state. The Tennessee-Nashville mine, also known 

 as the Havilah, claims to have operated the first stamp mill in California, 

 and ore from the mine was crushed in arrastres previous to that time. 

 The Tennessee-Nashville was the first lode mine in El Dorado County and 

 one of the first in the state. The stamp mill was manufactured in Cincin- 

 nati and brought around the Horn. Known production for the Tennessee- 

 Nashville is in excess of $231,000 but there are no records for several 

 periods of activity. The mine is about 1000 feet deep. 



North of the Tennessee-Nashville a distance of 1.3 miles are the 

 dumps of the Montezuma mine. The Montezuma had considerable elab- 

 orate equipment at the site in the 1930 's but this has since been removed. 

 The Montezuma has a history similar to that of the Tennessee-Nashville 

 with which much of the development work has been connected. Imme- 

 diately north of the Montezuma mine the old and historic Kings Store 

 road leads off to the northeast. This road connects with the Red Bird, 

 Union, Martinez, and Crusader mines which are along Martinez Creek. 

 The Union is credited with being the largest producer in El Dorado 

 County. Incomplete production figures indicate a yield in excess of 

 $2,700,000. 



Two mines, the Pocahontas and the Ophir, are located in Logtown 

 Ravine close to Highway 49 between two and three miles southwest of 

 El Dorado. They are of interest to geologists because the veins are on the 

 contact of Logtown Ridge meta-andesite and a quartz porphyry and may 

 not be related to the Mother Lode. The quartz porphyry is closely asso- 

 ciated with granodiorite in this locality and is either derived from it or 

 intimately intruded by it. The Pocahontas is more than 1000 feet deep 

 along a rather shallow dip of about 45. 



Two miles south of El Dorado several ruins of old stone buildings 

 can be seen on either side of the highway. The best preserved of these is 



a partly dugout structure half of which is below ground level. A sub- 

 stantial part of the walls are made from granodiorite arrastre stones. 

 Arrastres were used extensively in connection with the mines between 

 Plymouth and Placerville and their partly shaped stones made good 

 building blocks. The arrastre method of grinding ore was borrowed from 

 the Spanish Californians but it is probable that those in the El Dorado 

 district were "Yankee" made. 



El Dorado, originally known as Mud Springs, was a camp on the 

 Carson Emigrant Trail long before gold rush days. The name was 

 changed during the height of the gold rush at the time of the incorpora- 

 tion of the town. Although attractively situated in the midst of a lumber- 

 ing, cattle grazing, and gold mining region, El Dorado has never gained 

 the impetus toward growth enjoyed by its near-neighbor Placerville. A 

 sawmill and lime plant are located close to town and many early day 

 buildings, both well preserved and in ruins, can be seen there. 



Diamond Springs is located near one of the richest of the early day 

 placer diggings in the vicinity of Placerville. Like El Dorado, it was an 

 emigrant camp before gold rush days. Both Diamond Springs and 

 El Dorado are to one side of the Highway 50 cross-country route but are 

 served by railroads and are active lumbering towns. 



Placerville was founded in 1848 either by James Marshall or a 

 Cosumnes River rancher named William Daylor. Both were there at 

 different times in the spring of '48. Placerville was known variously as 

 Old Dry Diggin's and Hangtown, but was incorporated as Placerville 

 in 1854. Placerville is probably the largest and most up-to-date town on 

 the Mother Lode, with vast lumber, railroad, and tourist interests. It is 

 served by Highways 49 and 50 and by the Southern Pacific Railroad. 

 The place is filled with old buildings and other spots of historical interest 

 which have been adroitly preserved among the modern structures of the 

 town. Many of the old buildings have been rehabilitated and house many 

 types of business enterprise. Placerville is also justly proud of its new 

 structures such as the County Courthouse building. Few places in Cali- 

 fornia are as steeped in early-day history as Placerville. Old placer and 

 hydraulic diggings surround the town on all sides and appear within its 

 limits ; fine old churches abound ; and the pine-covered hills to the east 

 of town form a fitting backdrop. J. M. Studebaker, who later founded an 

 automobile empire, learned his trade in the blacksmith shops of Placer- 

 ville. Although the gold of the vicinity has been largely dissipated, the 

 timber and water resources remain and the county still flourishes. 



In addition to the placer diggings, several lode mines were developed 

 near Placerville. The most successful of these is the Pacific Quartz mine 

 situated on a hill on the south side of town. It is- about 2000 feet deep via 

 vertical and inclined shafts and winzes. The ore is gold-bearing arseno- 

 pyrite containing considerable silver. Some ore bodies are in talc schist. 

 The wall rocks are Mariposa slate. There are intrusive bodies of serpen- 



