i6 



University of California. 



[Vol. i. 



Analysis of Granite from 



Quarry at Carmelo Cove. 

 71.63 



Si 2 

 Ti O, 

 Al 2 O a 

 Fe, 3 

 Fe O 

 Ca O 

 Mg O 

 K, O 

 Na 2 O 

 P a o 5 



trace 



13-86 

 0.46 

 2.76 

 3.26 



trace 



0.20 



2.65 

 340 



Ignition 



.89 



Sp. g. 



99. ii 

 2.68 



Later Granite Dykes. — The dykes of later granite which intersect 

 the Santa Lucia mass vary in size from an inch, or a few inches, to 

 several feet in width. The smaller dykes, less than a foot in width, 

 are more common than the larger ones. They appear to have no 

 prevalent trend but traverse the older mass in all directions. They 

 are inclined at all angles to the horizon. They are not so abundant 

 in the immediate vicinity of Carmelo Bay as they are a little to the 

 southward. 



The rock of these dykes is much finer grained than the Santa 

 Lucia granite. It is commonly not appreciably porphyritic, and in 

 those dykes where phenocrysts of orthoclase appear the latter are 

 of small size. The rock is much more compact or less friable than 

 the Santa Lucia rock, and does not appear to be affected by the 

 irregular minute cracks which traverse the latter. Since the dis- 

 turbances which have affected the Santa Lucia mass are of later 

 age than the dykes, the suggestion that the cracks in the former 

 are due to the presence of the large phenocrysts, rather than to 

 orogenic movements, is strengthened. The dyke rock is character- 

 ized by a paucity of mica, and this is so pronounced locally that it 

 may properly be regarded as an aplite. It is either gray or slightly 

 flesh tinted, and the feldspars are usually more or less kaolinized. 



These dykes sometimes show very beautifully the shearing to 



