86 GEOLOGY. 



This formation is distinctly traceable at various points up the coast, and in the neighborhood 

 of Santa Barbara is seen to form mountain masses. Wherever noticed, it is overlaid by various 

 sandy layers, forming an upper capping of very variable thickness. 



The irregular layer of interstratified pebbles, so frequently seen in hill-sides, seems hardly 

 capable of being referred to any distinct place in the general Tertiary series. Their most 

 abundant occurrence, however, near the mouths of valleys opening on the sea, sufficiently indi- 

 cate that they are derived from the combined agency of river transportation and tide-washing — 

 having attained their present position by subsequent land elevations. 



The junction of this Tertiary formation with the adjoining granite or igneous rocks is seen in 

 a general thinning out of the former, which, at last, barely mantling the protruding rocks, is 

 blended with the result of present decomposing agencies. 



Natural terraces and table summits. — Another interesting geological feature, observable in the 

 post Tertiary strata adjoining the coast, is the existence of natural terraces and table summits, 

 of various elevations, and their evident connexion with ancient sea levels — thus indicating suc- 

 cessive periods of land elevations. 



A series of at least three of these terraces is distinctly noticeable near the initial point of 

 boundary on the Pacific. 



The highest of these is exhibited in that striking landmark appropriately named "Table 

 Mountain." Visible, far out at sea, and attaining an elevation of not less than one thousand 

 feet above the present sea level, it presents a distinct outline of abrupt slopes terminated by a 

 regular flat table summit. As it now stands in its isolated character, and not far from the sea 

 beach, it appears to be altogether unique, though, doubtless^, more extended and accurate obser- 

 vation of height and situation would show its connexion with some of the higher terraced 

 elevations adjoining the interior mountain slopes. 



The next stej) in the descending series is represented in the average level of the post Tertiary 

 bluffs and hills near the coast, say at a present elevation of two hundred to four hundred feet 

 above the sea. The irregular character of the deposit, at various points, and the evidence of 

 long-continued denuding influences, have necessarily obscured the general level; or, as we may 

 suppose, the land elevation at this period was itself irregular or alternating with periods of 

 depression. It may further be remarked, as substantiating this latter view, that the deposits 

 here exhibited are those most abundantly characterized by the presence of transported rounded 

 pebbles, irregularly distributed, as we have seen, along the course of valleys of denudation. 



The third well marked terrace formation in the descending, or more recent series, occurs in 

 close proximity to the present sea beach, and is characterized by a more alluvial deposit, and also 

 the first appearance of recent marine shells, stre^fu irregularly over its surface in comminuted 

 fragments. A fine example of this formation is met with where the initial point of boundary 

 on the Pacific is marked by the first monument. Attaining an elevation of forty to fifty feet 

 above present tide water, it presents a steep slope seaward, and extends in quite a regular 

 terrace to the adjoining broken hills, before noticed, as constituting the middle terrace for- 

 mation. 



This last step in the series presents in its organic remains, and more alluvial character, an 

 approach to the present alluvial tracts of this region. 



Further north, where, from the western bend of the coast the Tertiary belt acquires its 



