1:34 J.K.MILLS ROCKS OF THE SIERRA N'EVADA OF CALIFORNIA. 



outcrops of then) there; but the serpentines of the upper subgroup and 

 all the members of the lower subgroup arc represented there, and among 

 them the fossiliferous limestones. These occur near the contact with 

 the unaltered upper Cretaceous (Chico) and Tertiary deposits, along the 

 West branch of Feather river, at intervals from Nelsons bar bridge at 

 the mouth of a creek coming in from the right, to near the mouth of 

 Cherokee run above the bridge on the road from Cherokee to Yankee 

 hill. Nelsons bar is in theN. E. I section 7, T. 21 N., R. 4 E., and the 

 mouth of Cherokee run in N. E. I section 21, of the same township, 

 according to a map of Butte county. These limestones are referred to 

 as near Pence's ranch by Whitney, and on identification of imperfect 

 specimens of fossils by Gabb, he called them Carboniferous.* They lie 

 on both sides of the river, which here flows in a southeasterly course. 

 They occur at different horizons in the section for about three-quarters 

 of a mile in width of outcrop (dips, northeasterly at very high angle, or 

 vertical). 



At the northeasternmost outcrops, which are on the left bank of the 

 river at Nelsons bar. serpentines are associated with the limestones. 

 There are also serpentines further southwestward, hut at the south- 

 westernmost outcrops (all on the right of the river) the limestones are 

 associated in places with greenstones, and a little farther southwestward 

 the greenstones become massive and continuous and form the crest of a 

 high ridge, on the southerly end of which is the village of Cherokee. 

 These greenstones are largely conglomeratic. I found no fossils in the 

 limestones on the left side of the river, but those on the right side of the 

 river ail' commonly fossiliferous, the fossils consisting principally of 

 fragments of crinoid stems. In my limited search I found no pen- 

 tagonal sections of stems, but many that were round with round central 

 canal, and some with lines radiating outward from near the canal. 



These limestones lie about 34 miles directly across the western divis- 

 ion of the range from the outcrops of limestone already described, 

 stretching for 20 miles from the northern end of the range to Claremont. 

 Here, as there, they lie in a series of slates, of nearly the same thickness 

 in each case, between greenstones on the one side and serpentines on the 

 other, with some greenstones associated with the lower limestones, and 

 serpentines near the upper ones. It is true, 1 found no pentagonal 

 crinoid stems in the limestone at the western foot of the range, but at 

 some of the exposures between Claremont and the northern end of the 

 range the sections of crinoid stems are also all round. I see no reason 

 to doubt that these limestones, with accompanying slates, greenstones 

 and serpentines, lying at the northern end of the range on the two sides 



Geologj of < alifornia, vol. i, L865, p. 209 ; Auriferous Gravels of t lie Sierra Nevada, 1879, p. SS. 



