384 Adventures in Scenery 



oysters, or "spat," brought from the Atlantic seaboard are 

 planted and matured. 



San Francisco Peninsula Made up 

 of Fault Blocks 



The San Francisco Peninsula, on the northern end of which 

 the city of San Francisco is located, is divided into two parts by 

 the northwestwardly trending Merced Valley. Millbrae and 

 San Bruno are at the southeast end of this valley where it merges 

 into the salt marshes of San Francisco Bay. Each part of the 

 Peninsula is a block of the earth's crust with a fault along its 

 southwest side, upheaved and tilted so that it has a gentle slope 

 to northeast. Both blocks have been worn by erosion so that 

 they have lost much of their original block-like appearance. 

 The block east of the Merced Valley is known as the San Bruno 

 block, and that to the west as the Montara block. The fault 

 at the west side of the San Bruno block is concealed by the allu- 

 vium of the valley. North of San Bruno Mountain (or block) , 

 between it and the Golden Gate is a group of hills, partly sand 

 dunes and partly hard granitic rocks, on and between which 

 the city of San Francisco is built. 



ROUTE E. SAN FRANCISCO, VIA THE GREAT VALLEY TO EL 

 PORTAL AND YOSEMITE NATIONAL PARK. 199 MILES 



Oakland, four miles from San Francisco; Hay wards, 13 

 miles; Tracy, 59 miles. 



San Francisco to Oakland, via High Bridge or ferry, four 

 miles. The route out of San Francisco basin is across the allu- 

 vial plain to Haywards. Cross San Leandro Creek at San 

 Leandro. This creek meanders across the flat plain after de- 

 scending from the foothills of the Diablo Range to the north- 

 east. Haywards is located in a bottle-neck or gap in a ridge 

 of igneous and metamorphic rocks which flank the Diablo 

 Range. East of Haywards is Castro Valley, through which San 

 Lorenzo Creek flows, swinging south and west through the gap 



