7 6 EDITORIAL 



since their beginning. The principal rivers of the region — the 

 Rogue River, the Klamath, and the Trinity — cut transversely across 

 the more nearly north and south ranges, showing them to be younger 

 in age than the lines of drainage followed by these streams, and 

 accordingly younger in age than the east and west ranges. 



The historical development of these drainage basins is shown by the 

 deposits contained in them, and for some of them it antedates the 

 later Cretaceous epoch's at least. The earliest drainage of the basin of 

 the Klamath lakes is shown to have been through the valley of Rogue 

 River, and to have been diverted from that course to its present, by 

 some of the later lava flows from the Cascades. Evidence is cited to 

 show that during the Chico epoch this basin was not connected with 

 that of the Pitt River or the Sacramento, and it is maintained that its 

 individuality has been kept almost unchanged to the present. As one 

 of the larger streams of the region therefore, the Klamath is younger 

 in age than either the Trinity or Rogue River. 



On the Age of Certain Granites i?i the Klamath Mountains. By 

 Oscar H. Hershey, Berkeley, Cal. Presented by A. C. 

 LAwson. 



Small batholites and dikes of granite, quartz-mica-diorite and 

 intermediate types are shown to occur at various places in the Klamath 

 region, but in areas quite subordinate in extent to those of the- 

 metamorphic rocks into which they have been intruded. The same 

 contains extensive areas of serpentine and instances are given of the 

 granitic rocks having been intruded into the serpentine to prove that 

 the granites are newer, in accordance with the determined relations of 

 these rock types in the Sierra Nevada region, and the reverse of the 

 supposed relation between the granite and the serpentine of the Coast 

 Ranges. 



The black slates of the Klamath region are divided into two dis- 

 tinct series, referred to as the Lower Slates and the Upper Slates. The 

 former are considered Devono-Carboniferous in age, being in part 

 equivalent to the Calaveras formation. The latter are correlated, on the 

 evidence of their lithology and of their structural relations to the Lower 

 Slates and to a certain extrusive greenstone formation similar to the dia- 

 base and porphyrite formation of the Sierra Nevada region, with the Mari- 

 posa formation of late Jurassic age. The intrusion of granite occurred 

 later than the deposition of these Upper Slates. Also it is shown that 



