94 



GEOLOGIC GUIDEBOOK ALONG HIGHWAY 49 



[Bull. 141 



material in towns, the building facades are of materials regarded as more 

 ornamental, such as brick or rhyolite tuff. 



Schists of the Calaveras, Cosumnes, and Mariposa series as well as 

 some similar formations of earlier age are extensively used as building 

 material. Their especial virtue lies in the fact that they usually have 

 well denned horizontal planes of cleavage which permit the detachment 

 of large, even surfaced slabs which can be used with very little dressing 

 or shaping (cf. Pigs. 11, 24). When used for fences or retaining walls, 

 they are often dry-laid (cf. Figs. 23, 166), but in buildings they are 

 usually set in mortar of mud or lime. When the vertical plane of cleavage 

 is definite, it is set toward the exterior. The rough, vari-colored appear- 

 ance of schist walls was not always appreciated by the early builders and 

 most schist buildings have facades of brick (Fig. 74) or of dressed blocks 

 of ornamental stone (mostly rhyolite tuff) and the other walls are heavily 

 coated with lime stucco. That the use of schist as a structural material is 

 confined to those towns where it is available in the immediate locale, indi- 

 cates that it was employed because of convenience rather than preference. 

 Representative schist buildings are illustrated in Figs. 17, 26, 55, 164. 



Granite, superb building material that it is, is seldom used in con- 

 struction in the Mother Lode. Perhaps it was regarded as a too pretentious 

 material for the essentially functional architecture of the mining camps. 

 San Francisco's first fireproof building the three-story Parrott Block, 

 was made of granite. It was "pre-fabricated," the blocks were cut and 

 fitted in China, marked with Chinese characters, and shipped to Cali- 

 fornia to be erected by Chinese labor in 1852. Local granite, quarried at 

 Quincy, was advertised for sale in San Francisco, by Coit and Beals at 

 the Sign of the Granite Obelisk, 94 Battery St. in a Jan. 1, 1854 advertise- 

 ment in the Alia California. The granite quarries at Folsom were opened 

 in 1856 and operated by convict labor. The Penryn granite quarry was 

 opened by G. Griffith in 1864. 



Rough quarried granite blocks used in early structures may be seen 

 at the old winery two miles east of Rescue (Fig. 128), at Lotus, and at 

 several places on Highway 49 between Lotus and Pilot Hill. Dressed 

 granite blocks are to be seen in Mariposa, the source being Mormon Bar 

 immediately to the south, and at Coloma (Fig. 131). 



Serpentine resembles meta-andesite agglomerate as far as its qual- 

 ities as a building material are concerned. Field stones of serpentine of 

 irregular sizes and shapes were occasionally used for structural purposes 

 in the immediate locale of their natural occurrence but no intensively 

 worked quarries were seen nor was there any evidence that the serpentine 

 was transported more than a few hundred yards. 



Talc schist, or soapstone as it is called in the Mother Lode, was 

 occasionally employed in its rough form in rubble walls of buildings (for 

 example the Butterfly Grocery in Mariposa) or in carefully sawed blocks 

 used as an ornamental facing material as it is in the Coulter Hotel in 



Coulterville and the window arches of the Cory Building in Auburn 

 (Fig. 148). It is surprising that a stone which is so easily worked and so 

 resistant to heat and weathering was not used more extensively. 



Limestone (including marble) is of very local occurrence, good 

 exposures being noted at Columbia, Murphys, Volcano, and Cool. Lime- 

 stone buildings can be seen in Douglas Flat and in Murphys and the 

 buildings in Volcano are almost completely constructed of this material. 

 Curiously, the limestone seems never to have been used for structural 

 purposes in the vicinity of Columbia although some fine marble was 

 quarried here in 1852 and shipped to San Francisco. E. R. Roberts of 

 Stockton established a marble yard at Columbia in 1857, and in that 

 year a block of Columbia marble was sent to the national capital to be 

 put in the Washington Monument. In 1852 a block of marble from the 

 Ringgold quarry measuring 48 by 22 by 22 inches and weighing 2700 

 pounds was cut for the Washington Monument, but whether it arrived 

 does not appear to be recorded in the account printed in the Alia Cali- 

 fornian, Dec. 3, 1852. The stone for the Broderick Monument in San 

 Francisco came from the Columbia quarry. 



One of the most important structural materials in use in the Mother 

 Lode region was brick. It was used throughout the area in the chimneys 

 and fireplaces of wooden buildings, and to frame the doorways and 



FIG. 2. 



Commemorative plaque on Telephone Ituililiii;; at French Corral, 

 Nevada County. 



