DIKES IX SAX LUIS OBISPO COUXTY 



233 



This tilting is local to this inclusion and must have been caused by the 

 intrusion of the sand from below. These features of 12 are shown in 

 figure 3. 



At number 13, 30 feet below 12, is an 18-inch dike of hard sandstone, 

 while 25 feet lower downstream, at 14, is a 1-inch dike which dips 60 

 degrees north 25 degrees west. This thin dike is very hard, and thin as 

 it is, and standing directly across the stream, has resisted the action of 

 the current and stands well up above the shales cut by it. Two feet 

 downstream from 14 is a 2-foot dike (15) of much fractured hard sand- 

 stone containing shale inclusions. These two dikes (at 14 and 15) are 

 shown in figure 2, plate 22, in which the hammer is near 14. 



Figure 3. — Dike exposed at 12. 



A 23^ to 5-foot sandstone dike showing the tilting of the shales at either side, due to the injection 



of the sand from below. 



Immediately downstream from 15 is a 3-foot intrusion with many 

 veinlets. On the downstream side of this dike there are several more 

 stringers of sandstone, as indicated on tlie plan and cross-section at 15 

 in figure 2. 



A 40-inch intrusion, containing shale inclusions and dipping 64 degrees 

 north 10 degrees west, is exposed on the east side of the creek at 16, 150 

 feet below 15. A short distance downstream from this exposure is a thin 



