1921] Clark: Lower and Middle Cambrian Formations 



5 



BRISTOL MOUNTAIN SECTION 



The Bristol Mountain section represents the section of Paleozoic 

 sedimentary rocks present in Bristol Mountain northeast of Cadiz, 

 California. The sediments range in age from Lower Cambrian to 

 Carboniferous and are present in two localities in the range ; one near 

 the southern end, or about two and one-half miles northeast, and the 

 other about five miles due north of Cadiz, San Bernardino County, 

 California. 



Estimated 



~ , .„ thickness 



Carboniferous: in feet 



White to gray or brown limestone which in many places is partially 

 crystalline while in others, where metamorphism has been more 

 intense, is altered to marble 635 



Middle Cambrian: 



Light gray to brown or black arenaceous shale containing numerous 



thin beds of sandstone and quartzite 120 



Lower Cambrian: 



Dark brown to blue, or black nodular limestone or marble, which is 

 very hard and is largely made up of nodules that weather out and lie 

 scattered over the surface 25 



Fine arenaceous shale containing numerous thin beds of sandstone 



and quartzite, replete with Lower Cambrian fossils 22 



Quartzite composed of well sorted quartz grains firmly cemented 



together 450 



Conglomerate composed of rounded quartz pebbles imbedded in a 



quartzite matrix 10 



Quartzite composed of well rounded quartz grains, cross-bedded near 

 the base, where it contains numerous fragments of feldspar; lies 

 unconformably on an erosional surface of the pre-Cambrian 

 granite 10 



Total section, feet 1,272 



