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[Vol. 2 



to nodules several inches in diameter and having a very sharply- 

 marked concentric structure. Owing to the obscurity of the 

 exposures, the thickness of these shales can not be ascertained, but 

 they form a well-marked horizon along the base of the hills, and 

 appear wherever they are exposed to be the chief constituent of 

 the basal formation of a thick series of rocks reposing upon the 

 Franciscan rocks above described. The dip of these shales is 

 easterly or into the hill at an angle in the road cutting above men- 

 tioned of about 30 to 40 . The probable course of the concealed 

 edge of this shale formation between the mouth of Strawberry 

 Canon and Hamilton Gulch is marked by a landslide topography. 

 In the shale on the road cutting there has been formed an 

 ammonite belonging to the genus hoplitcs, and in other outcrops of 

 the same formation both to the north and to the south of Berkeley 

 forms of ancclla Piochii have been found. Both of these forms 

 occur characteristically in the Knoxville formation, which is the 

 basal member of the Shasta-Chico series. On the basis of these 

 fossils, and on account of the petrographic similarity of the whole 

 with the Knoxville shale in other parts of California where fossils 

 are more abundant, as well as the stratigraphic position of the 

 shales, the formation of which they are a part is referred with 

 little doubt to the Knoxville or lower member of the Shasta-Chico 

 series. 



Unconformable Relation to Franciscan. — On passing from the 

 Franciscan rocks to the overlying strata, whether they be Knox- 

 ville shales or still higher beds, we can not fail to be impressed with 

 the general contrast in the character of the respective formations. 

 The Franciscan sandstones, for example, appear to be much harder 

 and more firmly cemented than the sandstones of later age. Large 

 quarries have been opened in the Franciscan sandstones in the 

 low foot-hills between Berkeley and Oakland, from which a large 

 part of the macadam has been obtained for paving the streets of 

 these cities. The sandstones of the Shasta-Chico series are equally 

 available for this purpose along the front of the range, but are 

 unsuitable because of their greater softness. The lower rocks, 

 moreover, have evidently been subjected to a greater degree of 

 disturbance than have the overlying strata. They are frequently 



