Street,
where the bed has been greatly crumpled, folded, and even wrinkled,
also at West 135th Street, at 7th Avenue, south of McComb's Dam bridge
on the Harlem River, west side of St Nicholas Avenue, about West 138th
Street, where there is a vertical mass 3 to 4 feet in thickness forming
a wall along the sidewalk for more than 60 feet. Dr. Julien describes a
fault vein at this locality 2 feet wide " filled by a friction breccia
made up of angular fragments of the hornblendic rock, inclosed in
brownish-white quartz, the walls of the fracture lined by hackly
projections of the torn rock along both sides, as if they had been
wrenched apart and rubbed together" (reibung-breccia).
There
is an immense bed on Spuyten Duyvil Creek, which is injected with vein
matter of quartz and coarse granite material. Hornblende schist occurs
at West 125th Street between Claremont and Riverside Avenues. There is
a hornblende rock exposure on the Speedway at 186th Street and Harlem
River, a hornblende schist in Fordham at Tremont Street, with epidote
at West 135th Street, at nth Avenue, a similar rock at 100th Street and
5th Avenue, in which under the microscope the thin section reveals actinolite rods and scales, with quartz and feldspar.
OTHER SCHISTS
Associated
with the hornblende, and regarded by Julien as derivative from them,
are actinolite and tremolite beds. An example of the former is at West
78th Street near Amsterdam Avenue, and at West 155th Street west of
10th Avenue, at Trinity Cemetery. Julien has thus described it: " This
consists of a fibrous, laminated rock of yellowish green color, made
up almost altogether of blades of actinolite, rarely exceeding 2 or 3
millimeters in length, parallel to the foliation. The intervening white
seams, often 1 to 10 millimeters thick, are occupied mainly by granules
of quartz, but in part, at the West 155th Street locality, by flakes of
a pinkish white mineral of aluminous odor on moistening and somewhat
harder
