146 University of California Publications in Geology [Vol. 7 



and Carmelo bays. The western limit of the series may be 

 roughly followed by the outeroppings of the granite in the lower 

 portions of the hills and over the more nearly level territory sur- 

 rounding the town of Monterey. On the summit of the main 

 ridge, two miles southwest of Monterey, and on the south side 

 of this ridge, both the shale and the granite are mantled by a 

 considerable thickness of brown to yellow sand, which prevented 

 the accurate mapping of the formations. One of the most favor- 

 able localities for observing the relations of the shale and the 

 granite is seen in a small creek near the middle of the town of 

 Monterey. The east bank of this stream stands perpendicular for 

 twelve feet or more. At the base of this section the solid granite 

 is exposed. Coarse-grained sandstone and boulders immediately 

 overlie the granite. Passing upward the beds grade into finer 

 sandstone. Near the top of the section the sandstone is replaced 

 by clay shale or mudstone. Several feet back from the precipitous 

 banks of the stream the typical whitish-yellow bituminous shale 

 was found in place, approximately thirty feet stratigraphically 

 above the granite, showing the rapid transition from sandstone to 

 shale. A slight tilting to the eastward is the only movement that 

 has affected the shale, excepting a few minor dislocations due to 

 faulting. The inclination of the strata from the horizontal is 

 seldom greater than fifteen degrees and frequently not over five. 

 In several localities immediately southeast of Monterey the beds 

 were found lying approximately horizontal. A conservative esti- 

 mate of the thickness of the beds would place it at no less than 

 two thousand feet. 



Lithology. — The character of the rocks and the theories as to 

 their origin have been dealt with at considerable length by Pro- 

 fessor Lawson in his publication to which reference has been made 

 above, and it does not seem necessary to do more than review 

 the general types of rocks that are found in this series. The 

 series, as exposed at the type locality, consists mainly of white 

 and light yellow shales, usually well bedded and very resistant to 

 weathering. The shale can be separated lithologically into three 

 types : ( 1 ) a soft chalk-like rock which appears to be largely of 

 diatomaeeous origin; (2) a eherty shale which is very brittle 

 and breaks with a smooth, glassy fracture; (3) an arenaceous and 

 argillaceous shale. In the upper portion of the series the dia- 



