226 Adventures in Scenery 



uplifting of the land the region was a peneplain that is, a 

 region reduced by stream erosion until it had comparatively 

 little relief. As the land was raised the streams were rejuve- 

 nated and cut their valleys to their present depths. During the 

 time of the uplifting of the land faulting of the rocks occurred, 

 and this has contributed materially toward the development of 

 the present topography of the highland area. 



The Eastern Front of the Plateau 

 a Steep Eroded Fault Scarp 



The eastern front of the highland area or plateau, facing 

 the desert, is generally a high, steep, eroded fault scarp repre- 

 senting a southeasterly extension of the Elsinore fault. The 

 descent from Monument Peak or Vallecito View (altitude 

 6,000 feet) on the Laguna Mountains to the floor of the valley 

 at the foot of the scarp is approximately 4,500 feet in four or 

 five miles. Farther south, from the top of Jacumba Mountain 

 to the floor of the desert is a descent of 3,000 feet in five or six 

 miles. Farther north, and east of the Elsinore fault zone, is a 

 series of northwest-southeast mountain ridges which are plainly 

 fault-block mountains associated with intermontane valleys 

 representing sharply defined sunken fault blocks. The Santa 

 Rosa Mountains form the greatest ridge, which is a distinctly 

 tilted fault block with a long, straight, steep scarp thousands 

 of feet high forming the southwest face and a slope from 7 to 

 10 miles wide descending northeastward from an altitude of 

 6,000 to 8,000 feet to sea level. The Santa Rosa Mountain 

 block is regarded as a typical high and large tilted and eroded 

 fault block. 



View from Cuyama Peak 



From the summit of Cuyama Peak (6,515 feet) a pano- 

 ramic survey of California's Peninsular Range is most impres- 

 sive, and to be long remembered. In 1870 this vivid word- 

 picture was expressed by W. A. Goodyear, who made a survey 



