22 



University of California. 



[Vol. i. 



the present be very largely a matter of conjecture. The only clew 

 we have as to the age of the rocks is their probable identity with 

 similar sandstones in Malpaso Canon which have intercalated with 

 them considerable beds of coal, and which are therefore probably of 

 Tejon (Eocene) age. The Malpaso Canon coal basin is also quite 

 similar structurally to the basin on Carmelo Point, being sharply 

 folded into a synclinal funnel, and let down by shearing and fault- 

 ing into the granite upon which it rests. Mr. Turner's opinion as 

 to the Tejon age of the coal-bearing formations of Central California 

 has already been quoted supra. 



THE MONTEREY SERIES. 



Petrography. — The rocks of the Monterey series, as displayed in 

 the vicinity of Carmelo Bay, are representative of the Miocene where- 

 ever it occurs for several hundred miles along the coast of Califor- 

 nia. They are prevailingly white or light yellowish strata of a shaly 

 character. They are soft and chalky and may usually be scratched 

 with the finger nail. Notwithstanding their soft character, they are 

 peculiarly resistant to weathering action, and yield little or no sed- 

 entary soil. This is due to their insolubility in meteoric waters. The 

 rock never presents any evidence whatever of decomposition or 

 secular decay, and wherever the rocks are exposed in road cuttings, 

 etc., the broken edges of the shale lose little or none of their sharp- 

 ness. The strata are traversed by numerous irregular jointages, 

 which induce a mechanical disintegration into sharp blocks. The 

 shale has very commonly a peculiar porous structure which may be 

 seen with the unaided eye, but better with a lens. The pores are 

 rounded or oval in sections afforded by the broken surface of the 

 shale. They are arranged in layers in the bedding planes. They 

 never anastomose, but always have a distinct individuality. Their 

 appearance suggests the removal by leaching of some soluble mate- 

 rial which once occupied the pores. This idea is sustained by a 

 more critical examination of them with a good lens. Such an ex- 

 amination reveals the fact that in very many cases the pores are the 

 hollow mouldsof minute univalve shells. As the character of the 

 pores is thus indubitable for a great many, it is a fair inference that 

 the whole of the porous structure of the rock is due to the leaching 



