CHAPTER VIII. 



ECONOMICAL GEOLOGY. 



Building materials in the vicinity of san franoisco. — San francisco sandstone. — Granite from honq kono. — Of tomales 

 bat. — Limestone of tomales bay. — Sandstones of benicia. — Sandstone and trap of vacaville. — Want of building 

 stone on the Sacramento and feather rivers. — Trap near upper end of the valley. — From fort reading to the 



columbia, trap everywhere on our route. — gold. no new deposits discovered. — country covered by recent 



volcanic matter. — gold of port orford. — coal. — efforts to find true coal on the western coast. — coose bay 



coal ; geological position ; physical and chemical characters j economical value. coal of bellingiiam bay; 



geological position; extent and thickness of the beds; associated fossils. mlocene flora. — llgnite beds of the 



upper Missouri. — Chemical and physical character of bellingham bay coal. — Its economical value — coal of Van- 

 couver's island; geological position. — Cretaceous rocks. — Parallelism of the chalk and tertiary of the upper 

 Missouri with similar strata on the pacific coast. — Physical character of the coal and its chemical composi- 

 tion. — Coal of cape flattery, probably the equivalent of the lignites of the cowlitz and coose bay. — Coal of 



santa clara, california. — coal market of san francisco. coal of the lota mine, chili. — coal of australia. 



Coal from toe eastern states. 



BUILDING MATERIALS. 



VICINITY OF SAN FRANCISCO. 



The only desirable building stone in tbe vicinity of San Francisco is the sandstone which 

 is fully described in the first chapter of the report, where its fitness for architectural pur- 

 poses is alluded to. It is very accessible, readily quarried and wrought, and will supply a 

 cheap building material in exhaustless quantities. Some varieties of this stone, especially 

 that quarried on Yerba Buena island, will even answer the demands of ornamental architec- 

 ture, being to a considerable degree handsome and durable. For more elaborate and expensive 

 structures, however, a more resistant as well as beautiful material will be sought ; something 

 which should fill the place of the granites, marbles, and finer freestones used in the eastern 

 cities. Granite is already used to some extent in San Francisco, and it is now, for the most 

 part, imported from Hong Kong, in China. In that part of California which we visited it 

 was observed in but one or two localities. From Tomales bay I obtained specimens of granite 

 which seems well adapted to architectural purposes. It is composed of small crystals of white 

 felspar and quartz, with minute scales of black mica, and forms a very compact and durable 

 as well as handsome stone. There is also, on Tomales bay, a light-colored crystalline limestone, 

 which, when obtained in blocks of sufficient size, will make an excellent building stone. It is quite 

 extensively used for making quicklime. I have also seen specimens of metamorphic limestone, 

 obtained in various parts of the Sierra Nevada, which, for beauty and durability, will almost 

 rival the white marble of Vermont or the Potomac. The sandstones which are quarried in the 

 vicinity of Benicia are similar in character to those of San Francisco, but are softer and less 

 desirable for architectural purposes than some found in the immediate vicinity of the city. 

 From Benicia to Vacaville, the San Francisco sandstone is accessible at many points, and the hills 

 which border the upper end of Suisun bay and Suisun valley on the west are composed of com- 

 pact trap, which will afford a resistant and durable building material, but one wrought with 



