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GEOLOGIC GUIDEBOOK ALONG HIGHWAY 49 



[Bull. 141 



tine near by which have been altered to talc-schist in some places. Such 

 talc and serpentine rocks are exposed near the Safeway Store parking lot 

 on the main street of Placerville. The Pacific Quartz mine has a recorded 

 production of $1,486,000. 



PLACERVILLE TO AUBURN MAP 7 



From Placerville, Highway 49 resumes a northwesterly trend and 

 soon leaves the Mother Lode to traverse an area almost lacking in lode 

 mines and having but widely scattered placer camps. The relief steadily 

 increases because of the proximity of the many forks and tributaries of 

 the American River. The steeper canyon slopes are heavily wooded and 

 the logged-off areas are covered with brush. For about four miles, High- 

 way 49 traverses a bedrock of Mariposa slate, Logtown Ridge meta- 

 andesite, intrusive quartz porphyry, and Calaveras schist ; beyond that 

 limit the bedrock is granodiorite for a distance of over eleven miles. 



Coloma, site of Marshall's discovery of gold in 1848, lies in a valley 

 traversed by the South Fork of the American River. The gravels from 

 which Marshall washed the gold which made history are not the old 

 Eocene deposits from which so much placer gold was taken, but rather 

 are reworked Quaternary sands and gravels. The gold found along 

 present day Sierran rivers is derived partly from recent erosion of gold 

 lodes but more generally from recent erosion of pre-existing stream 

 deposits. The timberlands which first interested Marshall have, for the 

 most part, been cut off, the gravels were soon exhausted and Coloma 

 is largely a town of memories. The vicinity of Sutters Mill and the hill 

 which overlooks it to the southwest have been set aside as state parks. 

 On the south side of town the home of the poet J. Edwin Markham can 

 be seen on the west side of the main street. Centennial observances have 

 resulted in the erection of many suitable monuments and a local-history 

 museum. 



Downriver a distance of 1.5 miles is the placer camp of Lotus. Lotus 

 was first known as Marshall and then as Uniontown. It once had a 

 population of 2000, but this dwindled to a handful once the placers were 

 exhausted. Two fine old brick structures remain on the site. A paved 

 road connecting Lotus with Shingle Springs and Highway 50 passes 

 through town and at its northern outskirts joins Highway 49. The Stuck - 

 slager mine is located near this road one mile south of Lotus. This pocket 

 mine was unusual in that the gold was associated with the vanadium 

 mica roscoelite. Roscoelite is a very rare mineral found in few other 

 places in the United States. It occurred in fine greenish-brown or clove- 

 brown scales associated with quartz and gold. None has been taken from 

 there for some time. 



Half a mile north of Lotus, a paved road turns northeast from High- 

 way 49 which connects with Garden Valley. The latter lies in a very 



scenic part of the Mother Lode which will be discussed in later para- 

 graphs. Two and a half miles beyond this junction is the ruin of Meyer's 

 Dance Hall and Wine Cellar. This local "miners' delight" was built 

 in 1855 and was the scene of many a gay escapade. It has been marked 

 as a historical site by the El Dorado County Chamber of Commerce. 



The Lilyama copper mine is located 5.4 miles northwest of Coloma 

 close to Highway 49 on the north side. The Lilyama is a minor working 

 developed before World War I. It is one of the few contact-metamorphic 

 copper deposits in the Sierran foothills. Copper values were in chal- 

 copyrite associated with pyrite. magnetite, and a little gold and silver. 



Eight miles beyond Lotus the old landmark Pilot Hill marks the 

 placer diggings and town of that name. Pilot Hill is not on the American 

 River and its diggings were in a remnant of Tertiary gravel which lies 

 on a greenstone bedrock of uncertain age. Fremont and his men were 

 reputed to be the first "Americanos" to visit the vicinity of Pilot Hill in 

 1844. Mining began there in 1849 but Pilot Hill was principally a 

 jumping-off place for the mines which were higher in the mountains. 



Slightly more than four miles north of Pilot Hill is the crossroads 

 known as Cool. This was an early -day placer camp of which almost 

 nothing remains. A garage and gas station are located at the junction of 

 Highway 49 and the Georgetown road. 



The route from Placerville to Cool via Garden Valley, Georgetown, 

 and Greenwood is in most respects superior to that traversed by High- 

 way 49 and might well be named an alternate to that highway. The 

 Georgetown turnoff is eight-tenths of a mile from the center of Placer- 

 ville and is a well paved, well marked road. The first three miles toward 

 Kelsey and Georgetown lie down a steep side of Big Canyon which is 

 heavily timbered with incense cedar, Douglas spruce, and yellow pine. 

 With the exception of a narrow belt of greenstone and an occasional 

 serpentine intrusion, the basement rocks along this road from Placerville 

 to Georgetown are Jurassic meta-sediments, chiefly Mariposa slate. The 

 Pacific Minerals Company slate mine is located on the east bank of the 

 American River a short distance above the bridge. It is 2.3 miles north 

 of the junction with Highway 49. The slate is mined for roofing granules, 

 the mineral fragments which are used as a wearing surface on asphalt- 

 felt roofing. 



Half a mile from the American River bridge, the road winds up the 

 narrow Kelsey grade which climbs from the bottom of the American 

 River canyon 1100 feet to the upland around Kelsey. Deeply weathered 

 remnants of the old Eocene surface abound in the Kelsey-Georgetown 

 area. Brilliant red soil and lateritic clays are exposed everywhere and 

 much of the present land surface is a resurrection of that which existed 

 at the beginning of the Tertiary period. Some of the gravel remnants 

 which lay on this surface proved to be rich in gold. Kelseys Ravine at 

 the present site of Kelsey was one of these. 



