224 . GUIDEBOOK OF THE WESTERN UNITED STATES, 



journey must be made ou the San Francisco ferries. The distance 

 across the bay is 4 miles, and the trip is made in the ferryboats in 

 about 20 minutes. In crossing the bay the traveler sees Goat (or 

 Yerba Buena), Alcatraz, and Angel islands to the right, Marin 

 Peninsula bjeyond them, and the Golden Gate openmg to the west of 



Alcatraz. 



Goat Island lies close to the ferry course across the bay. Like most 

 of the other islands in the bay, it is owned by the Government. On 

 the nearest point there is a lighthouse station, and below it the 

 rocky cliff is painted white to the water^s edge. Just to the right of 

 this is the supply station for the hghthouses of the whole coast from 

 Seattle to San Diego. Behind this station is the United States naval 

 training station, of which the officers^ quarters may be seen on the 

 liillside and the men's quarters near the larger buildings below. At 

 the extreme northeast point of the island is a torpedo station, where 

 torpedoes are stored for use m the coast defense. 



On Alcatraz, the small island west of Goat Island, is a United 

 States military prison, and on Angel Island, north of Alcatraz, are 

 barracks and other mihtary buildings, a quarantine station, and an 

 immigrant station. 



Few people in viewing the Bay of San Francisco think of it in any 

 other way than as a superb harbor or as a beautiful picture. Yet it 

 has an interesting geologic story. The great depression in which it 

 lies was once a valley formed by the subsidence of a block of the 

 earth^s crust— in other words, the vaUey originated by faulting. The 

 uplifted blocks on each side of it have been so carved and worn by 

 erosion that their blockhke form has long been lost. Erosion also has 

 modified the original valley by supplying the streams with gravel and 

 sand to be carried into it and there in part deposited. The moun- 

 tains have been worn down and the valley has been partly fiUed. 

 Possibly the valley at one time drained out to the south, Ilowever 

 that may be, at a later stage in its history it drained to the west 

 through a gorge now occupied by the Golden Gate. Subsidence of this 

 part of the coast allowed the ocean water to flow through this gorge, 

 transforming the river channel into a marine strait and the valley into 

 a great bay. Goat Island and other islands in San Francisco Bay 

 suggest partly submerged lulls, and such in fact they are. 



San Francisco, the chief seaport and the metropolis of the Pacific 

 coast, is the tenth city in population in the United States and the 



San Francisco. 



Population 416,912 



largest and most important city west of Missouri 



Kiver, The population in 1910 showed a gain of 20 



omato1782 muet P^^ ^^V^ smce 1900. Tlie city is beautifully situated 



at the north end of a peninsula, with the ocean on one 

 side and the Bay of San Francisco on the other. The bay is some 

 50 miles in length and has an area of more than 300 square miles. 



