GLA UCOPHANE AND A SSOCIA TED SCHISTS 74 1 



certain, however, as the rocks may have been faulted into their 

 present position. About two miles north of the Junction School- 

 house, on the eastern flanks of the hills, are jaspers intruded by a 

 serpentinized dike which has apparently had but little meta- 

 morphic effect. 



In a hillside cut on the Healdsburg road about half a mile 

 east of the Schoolhouse, there is an excellent gradation from 

 slightly altered shale to entirely crystalline glaucophane and 

 actinolite schist. Specimens can be collected showing every 

 degree of alteration. Thin sections of the least altered shale 

 show incipient development of glaucophane in crystalline tufts 

 and radiate aggregates. 



Camp Meeker. — At Camp Meeker, Sonoma county, about 

 twenty-five miles southwest of Healdsburg, glaucophane and 

 actinolite schists are developed over an area which appears to 

 be at least a mile wide and several miles long, though the limits 

 were not determined. 



Intrusive in the schist are small dikes of a pyroxene rock which 

 are themselves somewhat schistose, and have glaucophane, actin- 

 olite, chlorite and mica developed in them. On each side of 

 these dikes the schist is of the normal glaucophane type and 

 contains glaucophane, actinolite, garnets and white mica. North- 

 east of the schist area is a mass of serpentine, but at no point 

 examined was the relation between the two rocks clearly shown. 



About half a mile north of Camp Meeker there is a gradation 

 from schist to shale in a distance of about three hundred feet. 

 The shale is hard a?id wrinkled, and contains some secondary mica, 

 but no glaucophane or actinolite. 



Tiburon. — The glaucophane schist area on the Tiburon penin- 

 sula is about two hundred yards wide, and extends more or less 

 continuously from Tiburon to north of Reed's station. Northeast 

 of the schist is serpentine which caps the hills; and southwest are 

 sandstones and shales. Near Reed's station, however, there is a 

 small area of the sandstone and shales, which, on the surface, 

 lies between the schist and the serpentine, and is in contact with 

 the serpentine. At the immediate contact the shale is somewhat 

 hardened but is unaltered at a distance of three feet. 



