SEDIMENTARY ROCKS 



L39 



and 2 of plate 17 will show how sharply the limestone is folded, and 

 figure 5 is a rough sketch of a crushed anticline and overthrust fault 

 chosen as one of many possible illustrations. There are anticlines with 

 almost vertical pitch, and the rocks have evidently suffered very much 



6 



Figure ( 



~5^ ~^~ 3 2 1 



-Sedimentariee : Blue Creek Series resting on Porphyry, north of Mount Scott. 



disturbance. It may be tentatively suggested, though the data collected 

 hardly warrant any generalization, that the rocks seem to have been 

 first thrown into a series of east- west folds parallel to the main mountain 

 range, and then thrown into cross-folds by the intrusion of the local 



granite mass 



To the east of the trail are high porphyry hills covered by a sedimentary 

 sequence having a fairly uniform strike and dip. Near the mouth of the 

 canyon a fault repeats the sequence as if to enable the geologist to check 



Figure 7. — Repetition of Cambrian Strata by Faulting, north, of Mount Scott. 



his work. Figure (> represents the basal portion of the section as far as 

 the fault, in figure 7 the fault and repetition are shown. The general 

 section of the beds from the base up is as follows : 



Feet 



1. Porphyry, rod, usual type. 



2. Sandstone, white, rounded grains, quartzitic, with one small di|> fault; 



dij>, 28 degrees 50 



.'). Conglomerate, dark colored, porphyry pebbles set in matrix of green sand 

 seemingly derived from disintegration of basic rocks ; Cambrian fossils; 

 dip, 30 degrees 250 



4. Coarse grained crystalline limestone with particles of magnetite and horn- 



blende ; dip, 29 degrees 30 



5. Dark sandstone, conglomeratic, with porphyry pebbles and much horn- 



blende ; dip, 24 degrees 1K0 



6. White calcareous sandstone weathering cavernous 70 



7. Limestone, blue, with fossils (Cambrian) ranging from -10 to 50 feet near 



the middle ; dip, 29 degrees at base, becoming 5 degrees at top 110 



Fault repeating first seven numbers. 



