84 



GEOLOGIC GUIDEBOOK ALONG HIGHWAY 49 



[Bull. 141 



DOWNIEVILLE TO SATTLEY MAP 10 



The northeastern end of Highway 49 lies along the headwaters of the 

 North Fork of the North Fork of the Yuba and then climbs out of the 

 Yuba drainage system and over Yuba Pass to the broad upland of Sierra 

 Valley. Yuba Pass does not show the tremendous alpine landscape that is 

 so typical of the passes to the south such as Tioga and Sonora. The great- 

 est relief to be seen on Highway 49 is along the route from Camptonville 

 to Sierra City. However, the end of the route is through heavily forested 

 country full of streams, and the beauty of the woodlands partly compen- 

 sates for the comparative lack of alpine features. 



Immediately east of Downieville the roadcuts are in a belt of black 

 slates which have been quarried for local use as a building stone. The 

 slates are full of quartz veinlets which have invaded the series along 

 the bedding planes. These slates closely resemble the Mariposa slates 

 of the Mother Lode but have been assigned to the Calaveras formation 

 by H. "W. Turner. Quartz veins varying in width from fractions of an 

 inch to two feet cut the country rock in many places along the road from 

 Downieville to Sierra City. Although barren for the most part, some of 

 these veins have been found to carry pocket gold. Several prospect holes 

 close to quartz veins can be seen on the south side of the river. Granodio- 

 rite outcrops in several places in this vicinity and the quartz veins were 

 undoubtedly derived from adjacent or underlying granitic intrusions. 



Camp Yuba, 5.4 miles east of Downieville, is another of the very fine 

 public camps situated on the banks of the river. This camp is near the old 

 placer camp site of China Flat. Several lode-gold mines are located both 

 to the northeast and southeast of Camp Yuba but none have been very 

 successful. The rocks along the highway between Camp Yuba and the 

 Ladies Canyon bridge include a small body of weathered granodiorite 

 which looks as if pre-existing wall rocks had been assimilated by it. It is 

 a dark, impure rock resembling a granite in texture only. Excellent exam- 

 ples of hill creep or false folding in platy meta-sediments may be seen 

 along the roadside in several places. Hill creep is produced on steep slopes 

 by gravitational bending of inclined strata in a downhill direction and is 

 usually the result of downhill movement of the soil mantle which lies 

 above the tilted edges of the stratified bedrock. 



Between Ladies Canyon and Sierra City a wide variety of interbed- 

 ded meta-sediments, meta-volcanics and dike-like intrusives are exposed 

 in the many roadcuts. Slate, phyllite, schist, chert, quartz porphyry, 

 serpentine, and green meta-volcanics can all be collected at various places 

 along the highway. Terrace alluvium perched high above the present 

 stream channel may be seen in the vicinity of Fournier Ranch and 

 Loganville. 



At the edge of Sierra City, a road leads off to the north which con- 

 nects with the Sierra Buttes mining district. As mentioned in preceding 

 paragraphs, the Sierra Buttes district is noted for the many large nuggets 



recovered there in early days. There is little or no activity in the district 

 at present. The columnarly jointed lava cap of Sierra Buttes can be seen 

 in many places along the highway in the vicinity of Sierra City. 



Sierra City, located at the foot of towering peaks on a narrow river 

 terrace, was first settled in 850 by gold miners. The vicinity was full of 

 Indian rancherias or camp sites and apparently was one of the most 

 heavily populated Indian districts in California. The new settlement was 

 destroyed by an avalanche in 1852 and the present buildings date from 

 the 1860 's or later. The main street of Sierra City resembles those of many 

 other towns of the gold country. The brick-and-frame Buseh Building has 

 the same iron doors and shutters that are so typical of fire-conscious towns 

 built in the 60 's and 70 's. Sierra City is famous for being the birthplace 

 of a roisterous society known as E. Clampus Vitus. The organization has 

 the reputation of being principally a perpetrator of practical jokes upon 

 the uninitiated. At any rate, name and reputation are colorfully con- 

 nected with the history of Sierran gold mining from Sierra City far down 

 the Mother Lode. The society was reorganized several years ago by the 

 California Historical Society, apparently with satisfactory results to all 

 concerned. 



East of Sierra City, Highway 49 passes close beside an east-west con- 

 tact between the quartz-porphyry bedrock and overlying glacial moraine 

 detritus. This is the first appearance of glacial debris along Highway 49 

 but morainal deposits can be seen in a great many places between Sierra 

 City and Bassett at the foot of Yuba Pass. The most obvious characteristic 

 of the glacial deposits is their extreme variability or heterogeneity. Clays, 

 gravel, and huge boulders both stratified and unstratified are dumped 

 together in irregularly shaped deposits. Some of the fragments or clasts 

 have been planed off or faceted by the ice. Others have been grooved or 

 striated by being ground against resistant bedrock. Most of the boulders 

 and smaller stones are merely rounded or subangular and one must exam- 

 ine many of them to find any which have characteristic glacial markings. 

 The quartz porphyry east of Sierra City is a light-buff rock with a very 

 fine-grained groundmass and numerous small, rounded, quartz crystals 

 or phenocrysts and less numerous rectangular or lath-shaped feldspar 

 phenocrysts. The rock is probably close to a dacite in over-all composition. 

 East of the quartz porphyry belt is a narrower belt of green porphyritic 

 meta-andesite breccia much like the Logtown Ridge formation along the 

 Mother Lode. 



A road connecting with Gold Lake, Sardine Creek public camp and 

 other parts of the Plumas National Forest joins Highway 49 4.3 miles 

 northeast of Sierra City. Sardine Lake and others in the vicinity are 

 cirque lakes of glacial origin. Except for the moraines to be seen along the 

 North Fork of the Yuba, glacial features are few along Highway 49 and 

 it is necessary to take side trips in order to see examples of glacial topog- 

 graphy. A road passable in summer connects with the glacial Packer Lake 



