Hershey — Some Western Klamath Stratigraphy. 59 



shales, near the southern end of Scott Yalley, as discovered by 

 Dr. A. C. Lawson and the writer several years ago. This may 

 be designated the Callahans fault. 



These faults are profound breaks comparable with the first 

 magnitude faults the world over, and may extend entirely 

 through the Klamath province, although this is said with less 

 confidence concerning the Callahans fault. The throw appears 

 to be generally not less than a mile and may in many places 

 exceed two miles, even where the dip is steep. The age as 

 indicated in the case of the Redwood Mountain and Callahans 

 faults by the strata involved, and perhaps in the Orleans fault 

 by its persistent accompaniment by serpentine dikes, seems to 

 be Cretaceous or later but not as late as the opening of the 

 Quaternary, Indeed, it is my impression that on the south, 

 Horsetown sediments lap across the Orleans and Black Bear 

 faults without dislocation. 



The territory to be especially considered lies along the 

 Orleans fault for ten miles northerly and southerly from the 

 Klamath River. Here it marks a remarkable change in the 

 stratigraphy. I will first describe the rocks east of the fault. 



With the exception of a small area of possible Salmon horn- 

 blende schist several miles south of the Klamath River, the 

 formation first encountered east of the fault in the vicinity of 

 Orleans is a great series of black shales, limestones and blue 

 cherts which, for the purpose, of this paper, I will designate 

 the Blue Chert series, from its most characteristic constituent. 

 This occurs in beds from fifty to several hundred feet in thick- 

 ness, made up of thin regular layers. The prevailing dark 

 blue-black color seems to have been bleached in places, some 

 outcrops having a whitish or light gray color. Also, isolated 

 areas of very limited extent possess red chert very closely 

 resembling typical Franciscan chert ; the invariable presence 

 of igneous rock suggests reddening of the blue chert by heat. 

 Between the chert beds are somewhat thinner layers of soft 

 black shale, much of which has been crushed to a schistose 

 structure. The limestones occur in small lentils, either iso- 

 lated or developed along certain lines parallel to the strike of 

 the shales. They probably represent definite horizons, of 

 which there may be several in the series. They are generally 

 thoroughly recrystallized and without recognizable fossils. 

 Indeed, the only fossils known between the Orleans and Black 

 Bear faults, in the Salmon River basin, which is largely occu- 

 pied by this series, are radiolaria in the cherts. The age, 

 therefore, can only be determined upon lithologic grounds. It 

 is presumed to be Devonian because similar rocks elsewhere in 

 the Klamath region carry Devonian fossils. 



