SCIENTIFIC BACKCJROUND 143 



that direction by the Orocopia Lineament which passes 

 by the north end of the Chuckwalla Mountains, and 

 which is described on a succeeding page. 

 THE LAWRENCE FAULT^ 



Besides the east-west extending Banning fault, on 

 the north side of the San Gorgonio pass, another and 

 parallel one was also observed by me on the south 

 side of the pass and named the Lawrence Fault. This 

 parallels the south side of the pass just south of 

 Banning and Beaumont and the north border of the 

 San Jacinto Mountains. It passes through the north 

 side of the Potrero de San Jacinto and enters the San 

 Gorgonio pass proper south of Cabezon Station, near 

 w^hich its course is marked by truncated facets. Its 

 course south of Banning makes a rectilinear fault val- 

 ley, which is easily identified on the United States 

 Geological Survey Map of the San Jacinto quadrangle, 

 and by springs and kernbuts which attend its course 

 through Lawrence's ranch, the locality from which 

 it has derived its name. The fault has not been traced 

 across the Badlands Range, and the presumption is 

 that it is an older feature. 



An associated fault line parallels the Lawrence fault 

 on the north within a mile's distance, and between it 

 and the valley of the pass at Banning. Knowledge of 

 the presence of the Banning and Beaumont east-west 

 faults through the San Gorgonio Pass, explain the 

 trough-like nature of that great feature. The Banning 

 and Lawrence faults are probably of pre-Pliocene 

 origin, although later movements have occurred along 

 them, and indicate that the pass existed as remotely 

 as that time, at least. 



'First mention. 



