218 QUICKSILVER DEPOSITS OF THE PACIFIC SLOPE. 



TheJutimate i elation to eacli other of all the strata of tbis great Cliico-Tejou se- 

 ries, as sliown by tlio mixed character of its fossils, is very perplexiug when that con- 

 dition is considered in relation to the established taxonomy of the formatians, bnt it is 

 very suggestive when considered with reference to a search after the complete sequence 

 of geological events. Indeed, su(;h a condition of things is what one ought to expect 

 to find somewhere ; bnt hitherto no other part of the world, if we except New Zea- 

 land, has furnished so strikingau example of the intimate connection of two geological 

 ages, or at least of such connection between the Cretaceous and the Tertiary. 



The Miocene. — No seiislble iion-conformity Is known to exist between the 

 Tujon and the Miocene, yet the distribution of these two formations 

 appears to indicate a change of level at or near the period wliich separates 

 them, for the Miocene frequently rests upon the metaraorphic rocks without 

 the intervention of other beds During the Tt^'on these areas of metamor- 

 phic rock must have been land and the subsidence must have been a 

 o-radual one. It may have been more rapid in some localities than in 

 others, however, and it thus appears not unlikely that an appreciable lack 

 of conformity may yet be detected at some point or points l^etween the 

 Tejon and the Miocene.^ The Miocene occurs on both sides of the Coast 

 Ranges and on the lower western flank of the Sierra. It is also abundant 

 in western Oregon, but is not well represented, if it exists at all, in northern 

 California. It is composed in large part of sandstones somewhat irregular 

 in texture and color and usually distinct from the earlier rocks. A great 

 area, however, is mostly occupied by extremely tine-grained schists. 

 These are associated with bitumen in the lower counties and extend up the 

 coast to Santa Cruz and beyond. They are unusually barren of fossils, 

 while the sandstones often contain almost incredible quantities of shells. 

 The San Benito Valley is very remarkable in this respect. 



The Post-Miocene upheaval. — Thc PHoceue of the Coast Raugcs is of very 

 limited extent and lies, as Professor Whitney showed, uncouformably upon 

 the Miocene, which is itself greatly disturbed. The combination of these 

 facts shows that a great uplift took place between the two. As has been 

 stated already, it is often far from easy to distinguish in detail the eflfects 

 of this upheaval from those of the Post-Neocomian disturbance, audit may 

 be added that still later uplifts further confuse the structure of the Coast 



• Since tbis memoir was transmitted Mr. J. Maroon states that he has ohserved such a want of con- 

 formitv as is mentioned in a former foot-note. 



