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University of California Publications. [Geology 



the Tehachapi Eange near Gorman's station are on this line, are of 

 similar composition and general appearance and doubtlessly belong to the 

 same series. They go under the Upper Pliocene sandstone near Gorman 's 

 station. The borax mines west of Eraser Mountain seem to be in con- 

 nection with another patch of them. Probably many other isolated areas 

 will be found in the southern Coast ranges (pp. 366-367). 



The Rosamond, according to Ilershey, is found in the low 

 mountain three miles south of Mohave, where the Exposed 

 Treasure mine is located; in Soledad Peak, four miles south of 

 Mohave ; in many of the hills near the Santa Pe railway, five 

 to seven miles southeast of Mohave ; in Castle and Desert buttes, 

 several miles north of Rogers dry lake ; and in a narrow belt, 

 rarely over several miles wide, trending eastwardly across 

 Mohave Desert north of the line of the Santa Pe railway to 

 beyond the town of Daggett. He suggests that the series also 

 outcrops near Randsburg and for unknown distances east and 

 south of Daggett. He includes within the series the sharp hills 

 of lava outcropping in the Mohave River Valley in the vicinity 

 of Barstow, and just northwest of Daggett he represents it as 

 exhibiting the following phases : 



1. Massive pink lava; appearance on casual survey much like ande- 

 site, but on close inspection with a hand microscope it seems as acid as 

 some rhyolites. 



2. White and purplish rhyolite; slightly porphyritic, with flow struc- 

 ture well developed so as to weather out with the appearance of a stratified 

 formation, thin-bedded and highly tilted. 



3. Breccia-conglomerate of lava and granite fragments. 



4. Red sandstones and red shales. 



5. Stratified fine and coarser tuffs of dark red color, tilted at a high 

 angle. 



6. Light red beds of coarse debris of pink granite, lava, etc. 



7. A coarse, roughly stratified dark-red tuff containing fragments of 

 black lava. 



The last bed is very thick. Its general appearance is like the red 

 tuffs of the Escondido series. Indeed all the members from No. 3 to 

 ]No. 7, inclusive, are strongly suggestive of the Escondido series. They 

 dip away from, and seem to rest unconformably upon the massive rhyo- 

 lites which are typically Rosamond. This only confirmed a suspicion 

 which I had before that the Rosamond and the Escondido series are of 

 about the same age, but that the former is slightly the older and fur- 

 nished the material for the fine-textured, supposed rhyolite tuff stratum 

 under the basic lava of Tick Canon.* 



* Tick Canon is tributary to the Santa Clara River and this locality 

 is about four miles north of Lang station on the Southern Pacific railroad. 



