242 



J. F. XEWSOM CLASTIC DIKES 



Except in one or two cases noted below, no connection is apparent be- 

 tween these interbedded sandstones and the intrusions, and the writer 



believes that most of 

 the intrusions along 

 the coast were deriv- 

 ed, not from the thin 

 sandstone beds ex- 

 posed in the sea cliff, 

 but from the sand- 

 stone which underlies 

 the shales of the entire 

 portion of the coast 

 shown in figure 10. 



DESCRIPTION OF DIKES 

 ALONG THE COAST 



The dikes will be 

 mentioned in their 

 order and particular 

 attention will be call- 

 ed to the more inter- 

 esting ones,beginning 

 with 28 at the right 



FigvreU.— Dike 29, West of Santa Cruz, California. 



An intrusion of hard sandstone from 3 to 6 inches thick, cutting ('qoutheast) end of SeC- 

 diatom shales. t-v /^ -, r\ 



tion CD, figure 10. 



At 28, figure 10, a three-inch intrusion of fine, bituminized sandstone 

 cuts the diatom shale to the top of the sea cliff, a height of about 30 feet. 



Eight hundred feet southeast of the mouth of Baldwin creek, at 29, 

 a 3 to 6 inch dike of hard, 

 brown, rather fine grained 

 sandstone is exposed with a 

 dip of 80 degrees north, 75 

 degrees west. It cuts the shale 

 to the top of the cliff, and, 

 owing to its hardness, pro- 

 jects several feet from the side 

 of the cliff at one place, as 

 shown in figure 11. A freshl}^ 

 broken piece of this sandstone 

 gave no odor of bitumen. 



An interesting intrusion of 

 the Santa Cruz region is that 

 of dike 30, a few hundred feet west of the mouth of Baldwin creek, and 



Figure 12.— Plan of Dike SO. 

 This dike is west of the mouth of Baldwin creek. 



