64 Hershey — Some Western Klamath Stratigraphy. 



formation east of the fault is not the same as the upper forma- 

 tion west of the fault. Which is the older ? 



It is beyond question that the Bragdon and Nordheimer can- 

 not be equivalents. The plane of the Orleans fault is so steep 

 that the horizontal displacement cannot exceed half a mile. 

 Five miles south of Orleans, the two formations would contact 

 along the fault if the serpentine dike were absent. Equiva- 

 lence would imply that a formation which preserved its char- 

 acter of alternating sandstone and shale over an area at least 

 20x50 miles, within half a mile lost all its sandstones except 

 the basal one, and then preserved invariable its new character 

 over 10X20 miles. 



The Bragdon formation comes up to the Orleans fault on 

 the west along a distance exceeding 50 miles, but no trace of 

 it has been found east of the fault short of the " eastern Brag- 

 don area." The Nordheimer formation comes up to the fault 

 on the east, but has never been identified west of it. Yet 

 within two miles these formations have thicknesses respectively 

 of 5000 and 3000 feet. There certainly is here a problem 

 worth considerable effort to solve. 



If faulting had not occurred, it is probable that the two 

 formations would somewhere be found in original contact. If 

 the Nordheimer is the older, it is probable that a portion of it 

 is buried under the Bragdon just west of the fault. If the 

 Bragdon is the older, it was removed by erosion previous to 

 the deposition of the Nordheimer east of the fault or else it 

 lies under the Blue Chert series, a very remote possibility. 

 The latter would imply that there are two cherty series of 

 identical characters and three systems of intrusive material. 



The Bragdon is more highly altered by shearing than is the 

 Nordheimer, but that is no criterion of relative age. The 

 Bragdon was softer and less able to resist a shearing stress. 

 Besides, the dynamical action operated only in the territory 

 west of the fault. 



But there is one feature about this western Bragdon which 

 makes it practically certain that it is younger than the Nord- 

 heimer. It is absolutely without a trace of any intruded 

 igneous material other than granite and serpentine (originally 

 peridotite chiefly). I made a similar statement in connection 

 with the " eastern Bragdon area " and Mr. Diller has taken 

 exception to it, so to be cautious I will modify the above 

 statement as follows : In the course of several hundred miles 

 travel in the western Bragdon area I have never observed any 

 evidence of intrusive rock except a few small masses of granite 

 and a few serpentine dikes, the latter usually on the borders. 

 This does not mean that within the Bragdon area there are no 

 igneous rocks other than those mentioned. In going west- 



