SIERRA NEVADA PROVINCE 



By OLAF P. JENKINS 



The dominant mountain range of California, the Sierra Nevada, 

 stands as a single and magnificent natural province, over 350 miles long 

 by 60 miles wide. Its eastern rugged wall was a challenge to early explor- 

 ers ; its western wooded slope, a revelation to immigrants who could see 

 from its heights the fertile flat lands of the Great Valley and the Coast 

 Ranges beyond. The deep canyons, waterfalls, and Big Trees from the 

 earliest days were an invitation to tourists from all over the world. Fine 

 timber and water power, summer pasture for stock, playgrounds in both 

 summer and winter all have made the Sierra Nevada a huge natural 

 resort and at the same time a useful garden spot unsurpassed in the world. 

 All these features and resources have nearly overshadowed its vast min- 

 eral wealth, which was by no means exhausted by the excited efforts of the 

 early gold miners. 



To describe this fine mountain province or to appreciate its character- 

 istic features, an understanding must be gained of how it was formed and 

 of what it is composed. Some knowledge of the geologic features involved 

 will also be found useful in understanding how the mineral wealth became 

 unlocked to mining ventures. 



The shape and form of the Sierra Nevada is the result of stupendous 

 geologic processes. The mountain range has a definite eastern escarpment, 

 formed by comparatively recent faults or displacements in the earth's 

 crust, which took place after the Sierra was raised to tremendous heights, 

 now over 14.000 feet. This eastern front towers as a saw-toothed, snow- 

 capped wall in sharp contrast with the depressed desert valleys lying 

 10,000 feet below at its eastern foot. The watershed of the range hugs 

 close to this eastern wall, while the western slope is a gradual descent 

 to the Great Valley of the Sacramento and San Joaquin Rivers. This 

 gradual western slope, however, is dissected and broken laterally by rock- 

 walled canyons of exceeding depth, cut by mountain rivers flowing west- 

 ward to the Great Valley. The uptilting of the Sierra Nevada was the 

 cause of the enormously accelerated flow of its streams, which resulted 

 in the cutting of canyons to the very core of the mountains. The mineral 

 deposits which lay hidden many thousands of feet in depth were thus 

 exposed to view and to exploitation. 



The southern end of the Sierra Nevada bends westward where the 

 Tehachapi Mountains and San Emigdio Range form the terminus of 

 the Great Valley. The southwestern point of the Sierra ends abruptly 

 against the junction of the famous San Andreas and Garlock faults. The 



southern slope gives way to the Mojave Desert on the south as the eastern 

 escarpment faces desert troughs of the Great Basin. 



The northern mountain surface of the Sierra Nevada disappears 

 abruptly under the Modoc lava fields and volcanic Cascade Range which 

 completely cover the older relief and separate it from the Klamath 

 Mountains of the northwest. 



The Sierran Gold Belt, traversed by Highway 49, starts on the south 

 at Mariposa which is located well back in the foothills and halfway between 

 the northern and southern limits of the Sierra Nevada province. The 

 highway, like the Mother Lode, runs northwestward to Plymouth, cross- 

 ing the Merced, Tuolumne, Stanislaus, Mokelumne, and Cosumnes Rivers. 

 From Plymouth, the course of the Mother Lode quartz veins is northward 

 to Placerville and beyond, terminating in the vicinity of Georgetown, 

 a distance of 162 miles from Mariposa by highway. 



Highway 49 leaves the Mother Lode at Placerville and continues 

 northwestward to Auburn, first crossing the South Fork, then the North 

 Fork of the American River. It continues northward to the famous 

 mining district of Grass Valley and Nevada City. From there it wanders 

 northeastward through the old hydraulic mining region of the gold- 

 bearing gravels of ancient Tertiary streams, the deposits of which now 

 lie near the tops of ridges, where they and their covering of volcanic 

 flows have been lifted by the uptilt of the Sierra. After crossing the deep 

 canyon of the Middle Fork of the Yuba River, Highway 49 reaches 

 Downieville, an important gold-mining district lying on a direct northern 

 trend of the gold-bearing quartz veins of the rich Alleghany district. 

 These in turn may be a continuation of the Mother Lode from George- 

 town. Highway 49 continues from Downieville eastward over the Yuba 

 Summit, ending at the edge of Sierra Valley. 



The entire course of Highway 49 and its side roads will take the 

 traveler through many of the principal mines of the Sierran Gold Belt, 

 a total distance of 277 miles. Lying to the west of the Mother Lode is the 

 Foothill Copper-Zinc Belt ; west of that is the belt of clays, lignite, and 

 quartz sands of the lone formation. Limestone deposits occur in places 

 throughout this region ; a cement plant at San Andreas boasts of one of 

 the largest kilns in the world. The productive resources of this highly 

 mineralized region include gold, silver, some platinum and even a few 

 diamonds, tungsten, copper, lead, zinc, manganese, chromite, iron, lime- 

 stone, dolomite, clay, lignite, sand, gravel, slate, and building stone. 



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