VERMONT. 93 
these secondary minerals radiate only in the zone of the cleavage of the slate. There 
are a few lenses of interleaved muscovite and chlorite. Considerable dark-gray, 
probably graphitic, matter in extremely fine particles, very little carbonate, prisms 
of futile up to 0.04 by 0,006 mm. and more rarely irregular angular masses of the 
same mineral, and finally some crystals of tourmaline, 0.36 by 0.008 mm. The non- 
metallic lenses referred to above are evidently the quartz-coated pyrite lenses. 
The chief constituents of this slate, arranged in descending order of abundance, 
appear to be muscovite (sericite), quartz, pyrite, graphite, magnetite, chlorite, car- 
bonate, besides accessory rutile and tourmaline. 
For the reason given the product of this quarry is destined almost entirely for mill 
stock, but the examination shows it to be a superior roofing shite. 
The following data were gathered at the abandoned quarry of the Union Slate 
Company a half mile east-southeast of Northfield: Bedding strike, X. 10° E., dip 80° 
W; cleavage strike, N. 4° E., dip .70° W. Strike joints dip, undulating, low west; 
diagonal ones strike N. 60°-65° W. and dip 75° NE. 
MONTPELIER. 
At the abandoned quarry three-fourths mile southeast of Montpelier and about 10 
miles north-northeast of the Vermont Black Slate Company's quarry at Northfield 
the strike of both bedding and cleavage was found to be N. 15°-20° E., dip 70°-75° 
W. This quarry was operated by means of three wide openings at intervals across 
the strike and communicating with each other by a 10-foot open cut, which also 
served as a drain. The quarry is said to have been abandoned on account of the 
large percentage of waste, which may have been the result of the complex opening. 
The slate appears to be essentially the same as that of the Northfield quarries. 
WESTERN VERMONT. 
Geological nit it ion*. — The broader geographical and geological relations of the 
western Vermont slate belt are shown in the map of the slate belt of eastern New 
York and western Vermont, and still more fully in the economic and structure sec- 
tion sheets of the forthcoming Mettawee and Fort Ticonderoga folios. 
The Ordovician (Hudson) schist of the Taconic range is bordered on the west, 
except along a stretch of 6 miles in Pawlet and Rupert, by a belt of Lower Cambrian 
rocks estimated as at least 1,400 feet in thickness, which include about 240 feet of 
greenish and purplish roofing slates. This boundary between the Ordovician and 
Lower Cambrian has recently been shown to represent not only an unconformity 
but a folded overlap.'-' In Pawlet and Rupert the schists of the Taconic range merge 
it the west through decrease of metamorphism into an irregular area of shales and 
*rits of the same (Hudson) age not less than 1,200 feet thick, which include about 
)0 feet of commercial reddish and greenish slate. These have long been quarried in 
jranville and Hampton, N. Y., and are described in detail on page 70. In places 
;he Lower Cambrian slate protrudes through the Ordovician slate areas; in others 
enticular remnants of Ordovician slate overlie the Lower Cambrian slate. The 
elationsof these two formations are more intricate in the New York part of the slate 
)elt than in the Vermont part, In Pis. XX and XXI their relations in the vicinity 
)f the chief quarrying centers are shown, as well as the location and form of nearly 
ill the slate quarries. c 
The slates of western Vermont were fully described by the writer in part 3 of Nineteenth Ann. 
Slept. U. S. Geol. Survey in 1899, and the matter appears here in revised form, but the general map, 
fl*l. XIII, is not republished. 
''See Am. Jour. Sci., 4th ser., vol. 17, 1904, p. 185. 
clt will be noticed that PI. XXI fits onto the eastern half of the northern end oi PI. XX. Thescale 
f these maps is so large that they can be used for prospecting purposes by studying the relations oi 
! he quarry locations to the symbols which designate the strike of the beds. See also p. 44. 
