48 WARKEN UPHAM, M.A., D.SC, F.G.S.A.^ OX THE SAN FRANCISCO 



" Within the area of destructive effects approximately 400 miles 

 in length by 50 miles in extent the intensity varied greatly. There 

 was a maximum immediately on the rift line. Water pipes, conduits, 

 and bridges crossing this line were rent asunder. Trees were uprooted 

 and thrown to the ground in large numbers. Some trees were 

 snapped off, leaving their stumps standing, and others were split 

 from the roots up. Buildings and other structures were in general 

 violently thrown and otherwise wrecked, though some escaped with 

 but slight damage. Fissures opened in the earth and closed again, 

 and in one place reported a cow was engulfed. A second line 

 of maximum destruction lies along the floor of the valley system of 

 which the Bay of San Francisco is the most notable feature, and 

 particularly in the Santa Rosa and Santa Clara valleys. Santa 

 Rosa, situated 20 miles from the rift, was the most severely shaken 

 town in the State, and suffered the greatest disaster relatively to its 

 population and extent. Healdsburg suffered to a nearly similar 

 degree. San Jose, situated 13 miles, and Agnews, about 12 miles 

 from the rift, are next in the order of severity. Stanford 

 University, 7 miles from the rift, is probably to be placed in the 

 same category. All these places are situated on the valley floor and 

 are underlain to a considerable depth by loose or but slightly 

 coherent geological formations, and their position strongly suggests 

 that the earth waves as propagated by such formations are much 

 more destructive than the waves which are propagated by the 

 firmer and highly elastic rocks of the adjoining hill lands. This 

 suggestion is supported by a consideration of the destructive effects 

 exhibited by towns and single buildings along the same valley line 

 which are situated wholly or partly on rock. Petaluma and San 

 Rafael, though nearer the rift than Santa Rosa, suffered notably less, 

 and they are for the most part on, or close to, the rocky surface. 

 The portions of Berkeley and Oakland which are situated on 

 the alluvial slope suffered more than the foothills, where the 

 buildings are founded on rocks. The same suggestion is further 

 supported from a consideration of the zone of maximum destructive 

 efiect on the south-west side of the rift. This zone lies in the 

 Salinas Valley. The intensity of destructive action at Salinas was 

 about the same as at San Jose, and the town is situated on the 

 flood-plain deposits of the Salinas River. Along the banks of the 

 Salinas River and extending from Salinas to the vicinity of 

 Gonzales, so far as our reports at present show, the bottom lands 

 v/ere more severely ruptured, fissured, and otherwise deformed than 

 in any other portion of the State . . 



" The Commission, in presenting this brief report, has had in 

 mind the demand on the part of the people of the State and of the 

 world at large for relial)le information as to the essential facts of the 

 earthquake. It has, therefore, not presumed to engage in any 

 discussion of the more abstruse geological questions which the event 



