BED-ROCK: PLACER COUNTY. 



83 



excursion was made into the region at the head of the South Fork of the 

 Middle Fork of the American, an important mining district not included 

 within the limits of the map. Returning to Georgetown, the explorations 

 were continued down the slope of the Sierra to Folsom, and thence upward 

 to Plaeerville, the vicinity of which important and central mining town was 

 thoroughly examined, as well as the region at the head of the Cosumnes 

 River, between Newtown and Grizzly Flat. The remainder of the season 

 was given to the principal mining localities in Amador County, nearly the 

 whole of which was gone over. Following the above geographical order, 

 pretty nearly, the observations made by Mr. Goodyear will now be given, 

 arranged under the various heads previously indicated. 





1. The Lilhological Character and Stratigraphical Position of the Bed-Rock. 



Immediately above Newcastle, on the line of the Central Pacific railroad, slates make their 

 appearance, and the country between here and Auburn consists partly of slate and partly of granite, 

 The slates here, so far as seen, generally strike northwesterly and stand nearly vertical. At Au- 

 burn the rocks are hard silicious slates, standing vertically or with a slight inclination to the 

 northeast : they strike about N. 20° W. These slates are excessively hard and compact, and can 

 with difficulty bo broken. Their color varies from light green to almost black. On the stage 

 road from Folsotti to Auburn, the granite continues until within three miles of the latter place. 



At Iowa Hill, at Wiessler's Claim, the bed-rock consists entirely of elate, generally very thin- 

 bedded, argillaceous, and sometimes apparently more or less taleose. Some of these slates are hard 



and very tough, and are then generally of a dark bluish color j but other portions are quite soft, mid 



then usually white. Their strike varies between N. 15° W. and N. 25° W, and thev stand 

 nearly vertical. At Wolverine, about two miles northeast of Iowa Hill, the slates strike N. 10 

 15° W., and have an almost vertical dip. At Metcalfs Claim, near Roach Hill, the strike of the 

 slates is N. 10° — 15° W., and their dip 00° - 



— 70° to the southwest. At the Morning Star 



Tunnel, on the southeast side of Indian Canon, nearly opposite Iowa J I ill, the strike of the slates 

 is pretty uniformly N. 10° — 15° W. At Strawberry Flat, Indian ('anon, a little above Inde- 

 pendence Hill, the bed-rock slates have a direction of N. 20° W., and dip at a high angle to the 



southwest, In the southwest pit at Elizabeth Hill, two miles south-southwest of Iowa J I ill, the 



slates stand nearly vertical, with the usual predominant strike in this district of ]S T . 15° — 20° W. 

 At King's Hill they strike N. 3o° W. and stand vertical. At Eefuge Canon, west of Wisconsin 

 Hill, the strike of the slates is N. 50° W. ; in the east pit at Elizabeth Hill, a little west of Refuge 

 Canon, it is N. 20° — 25° W. 



At Nahor's Claim, in Green Valley Gorge, about five miles northeast of Iowa Hill, the bed-rock 



is entirely serpentine, and it is said that this rock can be traced for many miles north ami south of 



this point ; Brimstone Plains, about four miles south-southeast of the Green Valley (Jorge, is said 

 1" he, on this belt of serpentine. At the Mountain Gate Tunnel, near Damascus, four miles east 

 01 Green Valley (Jorge, the bed-rock is a very fine-grained, thin-bedded clay-slate, which, if a little 



harder, might make good roofing-slate ; its dip is nearly vertical, with a slight inclination some- 

 times to one side and sometimes to the other ; Strike N. 10° — 15° W. The color of these slates 



,s variable, the lighter colored being the softest; the dark bluish-black varieties are often Billed with 



Small cubical crystals of pyrites. I U the Lower Tunnel the slate is everywhere dark m color. At the 



dement Mill Claim, near Damascus, the slate is more or less taleose, ami some of it very much so. 



•the summit of Secret Mountain, on the road from Damascus to Canada 1 1 ill, near the head of 



