Bulletin . ture of the geology of this district is the largearea of serpentine to the south and southeastward from New of the ridges and slopes within tliis area are characterized bythe scarcity of underbrush and the sparseness of the timber growth(see Photo 17). In such places the serpentine is light colored, paleblue and green, and pulverulent. In other portions of this serpentinearea where the reddish color of the soil indicates the presence of iron,the underbrush is fairly abundant. This is particularly the case on Beckor. G. F., Goolo^y of the nuirk.^llver deposits of tlie Paci
Bulletin . ture of the geology of this district is the largearea of serpentine to the south and southeastward from New of the ridges and slopes within tliis area are characterized bythe scarcity of underbrush and the sparseness of the timber growth(see Photo 17). In such places the serpentine is light colored, paleblue and green, and pulverulent. In other portions of this serpentinearea where the reddish color of the soil indicates the presence of iron,the underbrush is fairly abundant. This is particularly the case on Beckor. G. F., Goolo^y of the nuirk.^llver deposits of tlie Pacific Slope: U. S. Mon. XTII, pp. 64, 189, 21.;, 2!tl-.^09, 46,^1-467, 18S8. -Forstner, William, Quicksilver resources of California: Cal. State Min. Bur.,Bull. 27, pp. 125-12!), ••Anrlerson, & Pack, R. W., Geology and oil of the west border of theSan .ToariuSn north of Coallnga, California: U. S. Geol. Surv., Bull. 60:i,pp. 2 00, et 1915. PLATE QUICKSILVER RESOURCES. 95 the westen> slope of Sampson Peak where the magnesite deposits arebeing worked. In the gravels of many of the stream beds in this area,chromite float and sands are noticeable. Some commercial shipmentshave been made of such chromite float gathered together; but thus farno bodies of workable size in place have been reported. Most of thesmaller quicksilver properties in the New Idria district are within thisserpentine area. The Aurora mine, a mile south of the New Idriamine, is just within the boundary of the serpentine, being not over ^mile from the contact. In contact with the serpentine along its northern edge, is a tongueof Franciscan shale and sandstone, this being covered to the north andeast by the overlying Panqche formation, a member of the Chico groupof the Upper Cretaceous. This latter formation is covered to thenorth by succeeding later Cretaceous, Eocene and other Tertiary sedi-mentaries in turn. The ore bodies of both the New Idria and S
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