154 



University of California. 



'[Vol. i. 



ward, the track has an altitude of 135 feet, being a grade of 11.5 

 feet to the mile; thus the longitudinal profile of the plain is a low 

 arch. If the surface of the plain once had a uniform slope, as our 

 assumption implies, this arch must be«due to local differential move- 

 ment or deformation of very recent date. 



The Salinas Valley. — This valley opens broadly on the Bay of 

 Monterey, and extends up between the Gavilan and Santa Lucia 

 Ranges as far as Santa Margarita, a distance from the mouth of the 

 Salinas of about 120 miles. Next to the Santa Clara-San Benito 

 Valley, it is the largest and most important of the many beautiful 

 valleys of the Coast Ranges. Like that valley, its course is remark- 

 ably straight, and has a northwest and southeast trend, being paral- 

 lel to the coast line. This valley also is occupied by a trenched and 

 terraced Pliocene delta, composed of generally horizontally stratified 

 beds of gravel, sand, and clay (the latter in the lower part of the 

 valley), resting uncomformably upon the upturned Miocene and 

 older strata, and being largely composed of the debris of white, sili- 

 ceous shale like that of the Monterey series. The structure of the 

 delta is well exposed in the many railway cuttings and natural 

 scarps of the upper portions of the valley. The delta material is 

 evidently very thick, but its volume cannot be estimated as closely 

 as on the San Benito. Stream terraces are abundantly represented, 

 and register clearly the different stages of the uplift. They have 

 been observed by the writer on the sides of the valley at numerous 

 localities from its lower stretches up to a little above Paso Robles* 

 The present summit of these delta beds has an observed altitude, a 

 little below Santa Margarita, of about 1,100 feet, and they probably 

 have a much higher elevation on the hills back of the railway, which 

 was made the line of a series of hurried observations. Thus again 

 we have in the topography and geological character of the valley 

 abundant evidence of its recent uplift; and, from the relation of the 

 valley to the Bay of Monterey, there can be no question as to the 

 correctness of correlating its stream terraces with the wave-cut ter- 

 races of Santa Cruz. It also seems clear that the valley in which 



* Three terraces were recognized by Trask and by Antisell in the lower 

 part of the Salinas Valley. See Jour. Senate Calif., 5th sess., 1854, append. Doc. 

 No. 9, p. 48. anJ Pacific Ry. Reports, Vol. VII, Part II, pp. 38, 39. 



