GEOL. VOL. I.] SMITHSANTA CATALINA ISLAND. 55 



appears to have a synclinal structure. Whether this is true 

 for the division to the southeast of the isthmus_ cannot be 

 stated. 



An excellent cliff section showing the general stratifica- 

 tion is seen on the southern coast of the west end, where 

 the bedding is distinctly visible for three or four miles along 

 the shore. For the greater part of the distance the dip of 

 the beds is quite uniform, though the minor beds and sheets 

 observed show intricate folding and crumpling. The dip 

 ranges from S. 15 E. to S. 45 E., at an angle varying 

 from 15 to about 30. 



On the northern coast of this part of the island the dip, 

 so far as observed, is northerly, and varies considerably in 

 amount, the average lying between 25 and 50. A char- 

 acteristic section of the bedding is shown in Plate III, fig. i, 

 a view of the shore at the north end of the beach of Cherry 

 Valley, the second small bay to the north of Isthmus Cove. 



The quartzites are nearly everywhere intersected by nu- 

 merous veins of secondary quartz, usually of small size and 

 running in various directions. In places, however, these 

 veins attain a width of a foot or more. At a number of 

 points some of the veins contain a small percentage of min- 

 eral ores. 



The quartzite is usually bedded in thin and more or less 

 irregular sheets. They range from a fraction of an inch to 

 two or three inches in thickness, averaging perhaps half an 

 inch. These sheets are usually separated by partings of a 

 dark earthy character, varying in thickness from the thin- 

 nest film to about a quarter of an inch. In the more thinly 

 bedded quartzite these partings are frequently thicker than 

 the quartzite sheets. 



Macroscopic Characters. The quartzite is occasionally 

 milky white; usually, however, as seen with a lens, it ap- 

 pears colorless and glassy. Rarely it is found black, while 

 here and there it occurs with a tinge of pink, or even con- 

 siderably reddened, owing to the presence of minute gar- 

 nets, either scattered through the sheet or arranged in bands 



