VERMONT. 10 1 
of a point within 2 miles north of Poultney, a change in the sediments occurred in 
Cambrian time sufficient to account for the diminished percentage of carbonate and 
the increase of chlorite and pyrite.« Whether this difference in composition is alone 
sufficient to account for the difference in the cleavage is uncertain. There may have 
been some difference in the resistance to pressure which would account for more per- 
fect cleavage at the south than at the north. Possibly, as has already been suggested, 
the greater abundance of grains of quartz at the north may have restrained the 
cleavage structure, and so with more lime deposited at the south and more quartz 
sand at the north the whole structural difference may be traced back to changes in 
sedimentation. 
Even this demarcation between the fading and unfading green slate areas is not 
absolute, for fading green slates occur well within the unfading green area, as at an 
old quarry 1£ miles southwest of West Castleton and again 1} miles south of Castleton 
and also a half mile south of Bomoseen. Slates which fade little are reported as 
occurring on the ridge west of Lake St. Catherine. In an old quarry about a half 
mile east of Jamesville, in a belt which seems to be directly continuous with that in 
which lie the Eureka and adjacent quarries, the slates fade comparatively little. In 
the Jamesville belt, at a quarry about 180 feet above the road and west of the chapel, 
there is a purple bed, probably overlying a green one; both purple and green fade 
badly, but on the west side of the purple, i. e., underlying it, is a green bed which 
scarcely fades and which, under the microscope, shows very few carbonate rhombs. 
A few things should be noted. The continuation of the West Pawlet slate is to be 
looked for in the lenticular Cambrian area which begins 2 miles south of West Pawlet 
and stretches across the New York State line into Hebron. Sea green and purple 
slates also occur in the Cambrian area southeast of West Pawlet. The Jamesville 
belt continues south into the village of Granville. About the north end of Lake 
St. Catherine the Cambrian slate belt divides in two, one part passing a half mile 
east of Poultney and the other a half mile east of East Poultney, where it crops out 
in the small gorge of the Poultney River. North of Castleton the strikes frequently 
change to the northwest or the north-northwest, and the beds of slate sometimes 
follow this direction. Barker Hill and Wallace Ledge both have Cambrian slates 
about them. 
QUARRY STRUCTURE. 
The types of structure exhibited at the quarries are shown in diagrams A-G, 
K-T, and V, on Pis. XXIII and XXIV, and also in PL XXV, reproduced from a 
photograph. The following table contains the more important coin pass observations 
taken at the quarries. The numbers in the first column will be found on the maps, 
Pis. XX and XXI. Where cleavage is given, but not bedding, the bedding is very 
nearly or quite the same as the cleavage. The usual dip joints may be assumed when 
not given. Approximations are indicated by the signs, plus ( ), minus ( ), more 
or less (±). 
To the data should be added a few observations at quarries outside the areas 
shown in the maps. An abandoned quarry three-fourths mile south of Lair Haven 
shows 24 feet of purple slate overlain by about 9 feet of greenish slate, dipping L5°-20° 
E. and containing three beds of quartzite, each 2 inches thick. The cleavage strike- 
N. 10° W., dips 25°-30° E. Joints strike N. 35° E., dip 60° E., also N. 50° E., dip 
90°. There is a fatal secondary cleavage— "false cleavage"— here, striking about 
north-south. See PL VI, A, and p. 24. At the Meadow Slate Company 1 1 diagrams 
Q, R, PL XXIV) and at the quarry just north of it bedding strikes X. 15° E, cleavage 
N. 7°-15° W., dip 15°-20° E. Vertical strike joints strike N. 15° E. and vertical dip 
joints N. 85° W. Diagonal ones strike NW., dip 65° NE., also N. 58° E., dip 90°. 
«The most southerly outcrop of decidedly unfading green observed by the writer occurs 2\ miles 
I * north-northeast of Poultney and three-fourths of a mile east of the railroad. 
