The Original Chazy Bocks — Brainerd and Seehj. 327 
tinuous with the same strata seen to the north. The long out- 
crop of dove-colored limestone'at the base of Group C. sudden- 
ly terminates at the south and is succeeded in the line of strike, 
after a short interval, by massive ledges of lower strata con- 
taining Maclurea macjna. 
On the north side of this western area are indications of still 
profounder disturbance. The rapid curvature in the strike of 
the Scalites beds (Grroup A. 5), their abrupt termination to the 
north-east, the presence still farther north-east of a large mass 
(indicated on the map without shading) of the crinoidal beds 
(Group A. 8), the existence of large irregular outcrops of Black 
River limestone between the brook and the railroad, — all in- 
dicate that we are approaching the axis of greatest dislocation. 
If we look a little further north we find a low hill of Pots- 
dam sandstone, around the south-east side of which the railway 
curves. Only forty rods to the east near the house of Kings- 
bury brothers is an outcrop of the Black River limestone, which,if 
it continued in the line of its strike, would come in contact with 
the sandstone. Eighty rods to the north-west of Mrs. Bugby's 
the railroad cuts through another exposure of the Potsdam 
sandstone, the apparent center around which curve the ledges 
of the lower Chazy, (Group A. ) south-east of Mrs. Bugby's. 
The strata of sandstone are nearly horizontal and stretch to the 
westward for fifteen or twenty miles. They are covered with 
but little soil and few trees, and form a desolate region known 
as the ''Flat Rock," useful chiefly for its enormous crops of 
blueberries. 
It is a noteworthy fact that the rocks of the Calciferous forma- 
tion which in Beekmantown, eight miles south, show a thick- 
ness of 300 or 400 feet, do not anywhere appear near Chazy 
village between the Potsdam Formation and the Chazy. Mr. 
Charles D. Walcott (U. S. Geolog. Sarv. Bull. No. 30, p. 22) 
thinks this an instance of non-deposition due to elevation of the 
sea-bed in this region while the Calciferous deposits were tak- 
ing place. But the non-appearance of Calciferous rock may be 
the result of a fault along a line between the railroad and 
Tracy brook, raising the rock on the north-west a thousand 
feet higher than on the south-east and producing the marked 
disturbances in the Chazy rocks under investigation. Just such a 
longitudinal fault appears on the east side of Isle la Motte 
