PREVIOUS GEOLOGIC WORK 197 



"Granite from one mile northwest of Browntown, Virginia, shows quartz, 

 orthoclase, plagioelase, hornblende, a little biotite, magnetite, and, along the 

 feldspar cleavage, chlorite. Another specimen from the same locality shows 

 the same minerals in larger crystals. A third specimen contains a large 

 amount of garnet in rude crystals and fragments, a little apatite and pyrite, • 

 and but very little orthoclase" (page 300) . 



In 1906, Weed and Watson 5 described the coarse-grained hypersthene 

 syenite traced by them at irregular intervals along the west side of the 

 Blue Eidge from Dickeys Hill, south of Front Boyal, in Warren County, 

 southward to Hightop and beyond in Greene County. Farther southwest, 

 at Stony Man, they stated that the field relations indicated the syenite to 

 be of later age than the Catoctin schist, which is regarded as Algonkian. 



In 1907, Watson 6 published a brief discussion of hypersthene syenite 

 and associated hornblende norite from a locality in the northern part of 

 Floyd County, Virginia. Attention was called to the close similarity of 

 the syenite from Floyd County to the unakite-bearing syenite at Milams 

 Gap, in Page and Madison counties, more than 100 miles to the northeast, 

 and to similar syenites of Norway. 



In 1913, Watson and Taber 7 published a detailed discussion, including 

 descriptions of a syenite-norite-nelsonite series of rutile-bearing rocks in 

 Amherst and Nelson counties, Virginia, and of the hypersthene syenite 

 occurring on the west slope of the Blue Eidge farther southwest in Eoa- 

 noke County. The Amherst-Nelson counties rock series shows striking- 

 relationships in mineralogy and chemistry to the granite-syenite-norite 

 series of the Blue Eidge igneous complex of the larger Blue Eidge 

 province. 



Quartz-bearing Hypersthene-Andesine Syenite 



distribution 



Quartz-bearing hypersthene syenite is one of the most abundantly occur- 

 ring granitoid rocks in the central Blue Eidge region. It has been ob- 

 served in the Blue Eidge and adjacent portions of the Piedmont Plateau 

 rts „j.merous exposures distributed over a distance of about 150 miles in 

 a northeast-southwest direction (see map, figure 1). The maximum 

 distance between extreme occurrences along a direction (northwest-south- 

 east) normal to the axis of the Blue Eidge will probably not exceed 30 



z W. H. Weed and T. L. Watson : The Virginia copper deposits. Economic Geology, 

 vol. i, 1906, pp. 309-330 ; see especially pp. 318-319. 



6 Thomas L. Watson : The occurrence of nickel in Virginia. Trans. Amer. Inst. Mng. 

 Engrs., 1907, pp. 306-316 ; Mineral Resources of Virginia, 1907, pp. 31-33, 580-582. 



" Thomas L. Watson and Stephen Taber : Geology of the titanium and apatite deposits 

 of Virginia. Bull. III-A, Virginia Geol. Survey, 1913, 308 pages ; see also Bull. 430, 

 U. S. Geol. Survey, 1910, pp. 200-213. 



