MOVEMENTS AND DEFORMATIONS 



345 



waves the solid rock is probably often fractured, though the fractures 

 are rarely observable at the surface where it is covered by deep soil. 

 Elsewhere the crevices are readily seen, especially if they gape. In 

 a few instances, surface-rock has been seen to be thoroughly shat- 



Fig. 279. Map showing in black the principal earthquake regions of the 

 Old World. (Montessus de Ballore.) 



tered after the passage of an earthquake, as in the Concepcion 

 earthquake of 1835. 1 Joints which were closed before, are often 

 opened during an earthquake. Thus in northern Arizona, not 

 far from Canyon Diablo, there is a crevice traceable for a con- 

 1 Darwin, Journal of Researches, 1845, p. 303. 



