342 QUAKTZ ROCK. 



St. Albans Bay the slates dip 30 E., near the line of junction (though at St. Albans Point 

 the dip is only 5 E.), while the Oneida dips from 5-10 E. At Milton the slate dips 

 12 S. E., and the red dolomite dips 10 E. At Charlotte the slates clip about 30 E. in 

 many places, while the dip of the sandstone is much less, say 12 E. At Snake Mountain 

 the slates dip to the east 15 more than the sandstone. These facts tend to the conclusion 

 that perhaps this unconformability may be traced over a wide area." 



QUARTZ ROCK. 



SYNONYMS. 



QUARTZ ROCK : Professor Chester Dewey's Geological Map of a part of Massachusetts, 

 etc. ; American Journal of Science and Art, I. Series, Vol. VIII ; 1824. 



QUAKTZ ROCK : Geological Report of Massachusetts, 1832 ; by Professor Edward 

 Hitchcock. 



GRANULAR QUARTZ, AT THE BASE OF THE TACONIC SYSTEM ; Professor E. Emmons 1 

 Works on the Taconic System; 1840, 1860. 



POTSDAM SANDSTONE : Professors H. D. and W. B. Rogers, Proceedings of the American 

 Philosophical Society ; 1841. 



POTSDAM SANDSTONE : Geology of the First District of New York, pp. 439, 440; by Pro- 

 fessor W. W. Mather ; 1843. 



QUARTZ ROCK, PERHAPS POTSDAM SANDSTONE : Third Annual Report on the Geology of 

 Vermont, p. 13 ; by Professor C. S. Adams ; 1847. 



POTSDAM SANDSTONE : Palaeontology of New York, Vol. I; by Professor James Hall; 1847. 



Lithological Characters. 



The general character of this formation is that of compact semi-vitreous sandstone. 

 The varieties of this species, and the associated rocks, are the following: 



1. Semi- vitreous, very compact, quartz rock. 



2. Granular gray, or reddish, quartz rock. 



3. Fine granular, or arenaceous, quartz rock. 



4. Granular porous quartz, or Pseudo-Buhrstone. 



5. Quartzose aggregate. 



6. Talcose and mica schists. 



7. Quartzose breccia. 



8. Quartzose and micaceous conglomerates. 



9. Limestone. 



The term quartz rock, or quartzite, as it is sometimes called, may embrace several min- 

 erals in its composition, at times, provided that quartz is the most abundant constituent. 

 In Vermont the term is applied principally to that great range at the west foot of the 

 Green Mountains, which forms a high mountain range between Pownal and Starksboro. 

 The greater part of it is a semi-vitreous or hyaline quartz, remarkably compact, and 

 seemingly a sandstone partially metamorphosed. This variety is traversed by numerous 

 joints, parallel to one another, and generally so near one another as to be mistaken for 

 planes of stratification, even by the most experienced eyes. The texture is often as fine 



