188 University of California Publications in Geology [Vol. 13 



so as to be inclined at a high angle to the even banding and then 

 merge into it. Along these curving planes are layers of coarse mus- 

 covite flakes. This rock probably represents an intermediate stage 

 between the fissile schists and the gnarly textured gneisses. 



Conclusions. — The Julian schists are the product of metamorphism 

 of a series of shales, fine clayey sandstones, and nearly pure quartz 

 sandstones, with subordinate layers of basic volcanic rock. In the less 

 metamorphosed portions the schistosity is parallel to the original bed- 

 ding of the rock. In the intensely metamorphosed portions there is 

 evidence of two directions of schistosity, the earlier conforming to the 

 original bedding, the later at a varying angle to it. The rocks exhib- 

 iting the double schistosity are characterized by peculiar minerals 

 generally ascribed to contact metamorphic action, i.e., sillimanite and 

 andalusite. 



The intrusive quartz diorite is without doubt responsible for these 

 contact minerals. There seems some reason, therefore, to attribute 

 the later schistosity to the action of the intrusion. The earlier schist- 

 osity is attributed to a time earlier than the intrusion. Further evi- 

 dence that the rocks were schistose before the intrusion of the quartz 

 diorite is found in the extensive development of lit par lit injection 

 gneisses and the total absence of hornfels along the contacts. 



Age of the Julian schists. — The earliest ideas that are of any value 

 in this discussion are those of Fairbanks/' In a paper on the geology 

 of San Diego, Orange, and San Bernardino counties he reports finding 

 fossils in limestone, inclosed in black shale and sandstone, four miles 

 up a canon which comes from the northeast and enters Silverado 

 Canon near its mouth. This seems to refer to Ladd Canon, south of 

 Sugarloaf Peak in the Santa Ana Mountains. (Shown on Corona 

 Quadrangle map, U. S. G. S.) These fossils were sent to the National 

 Museum and pronounced Carboniferous. Fairbanks concluded that 

 the metamorphic rocks of the Santa Ana Mountains were equivalent 

 to the crystalline schists of the Julian gold belt. He continues : 



This is a belt of schists which runs through the heart of the Peninsula range, 



from the Mexican line through the Santa Ana Mountains I believe that there 



is no question but what the metamorphic rocks of the Santa Ana range are 

 equivalent in age to a large part of those in San Diego county. Although none 

 but Carboniferous fossils were found, it is probable that the Metamorphic Series 

 contains rocks much older as well as younger.? 



s Fairbanks, H. W., California State Mineralogist, Eeport (XI), 1893. 



6 Ibid., p. 115. 



7 Ibid., p. 118. 



