24 SOUTHERN CALIFORNIA GEOLOGY 



inally built ever stood at all. Its architecture was 

 expressed by an extravagant use of wide spanned, un- 

 stable arches, such as have been known to endure for 

 centuries in Spain and Morocco, where good lime, ce- 

 ment and stone abound. On the other hand, the San 

 Juan Capistrano Mission was built of inferior, unburn- 

 ed bricks and triangular, soft-sandstone sprawls, laid in 

 limeless mud which by no stretch of imagination could 

 be called mortar. Surmounting the structure which 

 was 175 feet long, whose roof was already weakened by 

 the fanciful addition of seven poorly constructed domes, 

 was a slender tower 100 feet high which fell upon the 

 roof and demolished it and twenty-nine people beneath 

 it. The whole structure was so fragile that the vibra- 

 tion from any passing truckload of today would have 

 demolished it, for it was a veritable house of cards. 

 Father Junipero's original church adjacent to the one 

 destroyed, and better built some fifty years before, 

 stands next door, today as perfect as ever. 



Equally strong testimony that these quakes were 

 not extraordinarily severe is the fact that the mission 

 church buildings at Los Angeles and San Gabriel which 

 were not shaken down were situated upon alluvial soil, 

 which is considered to be dangerous as a foundation 

 material by some people. The perfect condition of 

 preservation of these structures proves incontestably 

 that no known tremors in Southern California have 

 been of sufficient power to seriously injure them, much 

 less to destroy them. 



It is a common thing to hear of the great de- 

 struction wrought at Inglewood in 1920. It has been 

 called that "most serious and damaging disaster," 

 while the truth of the matter as we have heard 



