20 



University of California. 



[Vol. 2. 



tion and extent of some of the outcrops indicated on the map are 

 problematical. There are two dikes in the steep face of the cliffs 

 back of the landing, and possibly one on the beach near it. The 

 most important outcrop, which furnished the best and most varied 

 material for study, is that forming the first precipitous point south- 

 east of the landing. The dikes outcrop along the coast for nearly 

 a quarter of a mile with steep cliffs, 200 feet high. The largest 

 dike begins a little back of the point just mentioned, and extends in 

 a southeasterly direction for a mile and a half. The road has been 

 graded into it near the landing, while further on toward the east, it 

 is shown in the canon of Wood's Creek, and in the next gulch a 

 half mile to the southeast. It finally terminates in a small outcrop 

 near the head of a stream flowing into the ocean east of the Chute. 

 All the dikes are intrusive in the Miocene, as were also the other 

 occurrences described in the former paper. The contact meta- 

 morphism is clearly shown in the first gulch east of Wood's Creek. 

 The dark clay shales and sandstone dip northeasterly at an angle of 

 30 , and have been intruded along the bedding planes. The strata 

 show an alteration for a distance of 75 feet. For the first 10 feet 

 the metaphorism has been sufficient to turn the shale into slate. 

 The alteration is nearly equal to that produced by the Cuyamas 

 dike. In the cliffs above the landing the dikes are also apparently 

 conformable with the dip of the inclosing shales, which is also to 

 the northeast. The eruptive mass at the big bluff has cut through 

 the shales, and at the top they rest partially on it. Boulders of the 

 teschenite also occur at the foot of the cliffs opposite the seal rock, 

 and it is possible that the rock of the little island may belong with 

 this group. 



Macroscopic Character. — The individuality of this rock type 

 as it occurs in the field is most striking. Point Sal is the fourth 

 locality where it has been found, and, although marked variations 

 occur, yet it has in general such a characteristic aspect that it is 

 not easy to confuse it with the other basic rocks of the Coast 

 Ranges. With the exception of a part of the large outcrop on the 

 cliffs, the Point Sal teschenite is a rather dark rock, often showing 

 the different components indistinctly. Near the surface, with the 

 exception of numerous hardheads, the rock is exceedingly friable, 



