LAYV5UN ~] 



PalacheJ 



The Berkeley Hills. 



357 



Metamorphic Schists. — Very commonly where these intrusions 

 invade the Franciscan formations there is found in their immediate 

 vicinity a more limited but very irregular and discontinuous /.one 

 of crystalline schists. These rocks can only be interpreted as the 

 products of contact metamorphism resulting from the reaction of 

 the heated emanations from the invading mass upon the encasing 

 rocks. The best local illustrations of such occurrences are on 

 Angel Island, which has been carefully studied by Ransome ; * on 

 the Tiburon Peninsula in Marin County, and on the flanks of the 

 Berkeley Hills north of Berkeley. The most characteristic mineral 

 of these metamorphic schists is the rare blue amphibole called 

 glaucophane, and they are therefore commonly referred to as 

 glaucophane schists. There is a small band of such glaucophane 

 schist exposed for a few feet in width in the sandstones, in the 

 portion of Strawberry Creek above referred to between College 

 Avenue and the mouth of the canon. The exposure is, however, 

 unsatisfactory, and it is impossible to make out its relations to the 

 eruptive rocks in the immediate vicinity. 



We thus see that, although the exposures of the Franciscan on 

 or near the campus are very limited in extent, we nevertheless 

 have represented practically all of its characteristic rocks, with the 

 exception only of the foraminiferal limestone. 



SHASTA-CHICO SERIES. 



Knoxvillc Shales. — As we begin the ascent of the hill on the 

 south side of the mouth of Strawberry Canon, we meet on the 

 cuttings of the canon road some beds of dark shale, some layers 

 distinctly argillaceous, others more sandy. These beds slack 

 readily under the atmosphere with a roughly concentric spherical 

 fracture and pass into soil readily; so that they are not seen in 

 natural exposures, and even in the road-cutting crumble away and 

 are mantled by the hill-wash from above so rapidly that they are 

 not now easily observable without some digging. These shales 

 are characterized in places by an abundance of rusty-yellow 

 limonite concretions, ranging in size from the dimensions of a nut 



*Loc. cit. 



