50 



GEOLOGIC GUIDEBOOK ALONG HIGHWAY 49 



[Bull. 141 



Woods Crossing, now a cross roads rather than a ford, has several 

 interesting features. It is marked by a sign commemorating the passing 

 of Bret Harte and Mark Twain through the gold country which was 

 placed there by the Tuolumne County Chamber of Commerce in honor 

 of two authors who did much to bring the color of the "Days of 49" 

 before the public. A short distance to the west of the crossing, the build- 

 ings of the Harvard mine can be seen on the slope of Whiskey Hill. This 

 mine was discovered in 1850 and was worked continuously until 1916. 

 The prominent quartz-ankerite outcrops close to which the ore lay also 

 outcrop conspicuously in the long roadcut between Woods Crossing and 

 Woods Creek. The multiple nature of the vein system can readily be seen 

 there and some minerals, such as the attractive mica mariposite, can be 

 obtained. The veins lie along the contact of Calaveras schist and the 

 serpentine body mentioned in preceding paragraphs. The Harvard has 

 two shafts but only one was used to any great extent. The main shaft 

 has a 700 foot vertical drop and then turns at an angle of 58 to a depth 

 of 1850 feet. The veins have been worked for 1500 feet along the strike 

 of the Mother Lode. Post-mineral faulting has displaced the ore shoots 

 from 8 to 20 feet in some places. A 60 stamp mill employing 1200 pound 

 stamps is on the property. Some recent development work has been done, 

 but no attempt at major production has taken place in recent years. 

 The Harvard has a known production of $2,036,697 but no records were 

 kept prior to 1897, and a much larger figure is probable. 



To the east of Highway 49, a road leads off to the old mining camps 

 of Stent and Quartz. Both can also be reached from roads out of Jack- 

 sonville and Jamestown, being about 2 miles south of the latter. In 

 addition to local placering, Stent and Quartz are famous for a group of 

 hardrock mines the best known of which are the App, Dutch, Sweeney, 

 Heslep, and Jumper. The Jumper has recently been rehabilitated but no 

 recent production has yet been reported. It is a consolidation of the old 

 Jumper, New Era, and Golden Eule claims, the combined production of 

 which is more than $3,000,000. The presence of the gold tellurides petzite 

 and hessite has been reported from the Jumper. Combined production of 

 the App and Heslep has been placed at more than $1,742,000 and that 

 of the Dutch and Sweeney at approximately $2,118,000. These were fairly 

 deep mines, the Dutch having a vertical depth of about 2070 feet. 



Beyond the Mother Lode vein exposures at Woods Crossing, a very 

 thick section of Calaveras rocks begins. The Calaveras formation can be 

 seen on both sides of Highway 49 from Jamestown to well beyond the 

 Calaveras Kiver bridge. The rocks are mica schists, phyllites, limestones, 

 and green metavolcanics. Several more or less parallel branches of the 

 Mother Lode traverse the Jamestown-San Andreas strip, and the vein 

 systems tend to finger out into the wall rocks in many places, forming 

 networks of veinlets or stringers. Some of the stringer lodes were 

 extremely auriferous and were responsible for the famous pocket mines 

 of Rawhide and Jackass Hill. Some of the ore bodies on Carson Hill 



were of this type. It is probable that a great deal of high grade ore of 

 this nature was eroded off during Cretaceous and Eocene time to form 

 the fabulously rich placers of Columbia and Shaws Flat. 



Jamestown or Jimtown, as it is familiarly called, is a still thriving 

 community with a history dating from 1848. It long has been the supply 

 center for a great many small mining camps, and the major workings 

 at Stent and Quartz lie nearby to the south. A veritable network of roads 

 branch off from Highway 49 in the vicinity of Jamestown all of which 

 traverse areas of mining and geological interest. The road to Stent and 

 Quartz has been mentioned in previous paragraphs. Another one leading 

 off northwesterly from the center of town crosses Table Mountain, goes 

 through the ghost town of Rawhide, and rejoins Highway 49 about a 

 mile east of Tuttletown. This route crosses Table Mountain close to the 

 old Tuttletown-Jamestown segment of the abandoned Sierra Railroad. 

 A closeup view of the latite lava cap and underlying tuffaceous sediments 

 can be seen in the railroad cut close to the road. The columnar structure 

 of the latite is particularly conspicuous. The rim, or contact with bedrock 

 along the old slope of the fossil stream bank, shows in the old weathered 

 surface of the covered schist, a cross section of surface hillside creep 

 which has been preserved since the lava covered it. Close by this spot 

 to the north is the location of the old New York Tunnel which drifted into 

 gold bearing gravels following a channel which led the miners beneath 

 Table Mountain. The gravels lie beneath rhyolitic lake beds, covered by 

 andesite cobble, all of which the lava of Table Mountain spanned like a 

 bridge. The New York tunnel was one of the few drift mines under 

 Table Mountain which could boast any considerable profit. Its heyday 

 was prior to 1868. 



West of the Table Mountain crossing, a distance of seven-tenths of 

 a mile, the Rawhide road joins one from the old Omega mining district. 

 Southeast of this road junction the red sheet metal stamp mill of the 

 Omega mine can be seen. Although the Omega mine has never been very 

 successful, the mill has been in operation for much of the time and is 

 one of the few stamp mills still in operation along the Mother Lode. 

 The mill site is of further geologic interest because a post-latite normal 

 fault, Pleistocene in age, passes almost under it and then cuts through 

 Table Mountain, displacing the lava cap a vertical distance of 60 feet, 

 the western side being higher than the eastern. 



The site of the old mining camp of Rawhide lies a short distance 

 north of the Omega-Rawhide road junction almost due west from the 

 railroad cut on Table Mountain. A body of pure antigorite serpentine 

 lies to the south and west of the town of Rawhide. This was extensively 

 prospected during the war as a possible source of magnesium. The Raw- 

 hide mine, also located close to the town of Rawhide, was one of the most 

 successful early day mines. It was very active up to 1867 ; was idle until 

 1891 ; and had a very productive period up to 1905. Since then only 

 pocket mining in the old workings has been done. The veins are typically 



