RECORDS OF MEETINGS OF 1909 
317 
ever obtained from the Staten Island serpentine were recently collected dur¬ 
ing the progress of excavating a trench for the first section of the retaining 
wall along the east side of Jay Street, near the ferry landing at St. George. 
A projecting spur of the eastern edge of the serpentine escarpment was cut 
away for a distance of some seventy-five feet, almost down to tide level, 
exposing a vertical face twenty feet in height and affording a view of the rock 
at a lower level than had been anywhere previously visible on the Island. It 
consisted largely of hornblende and amphibolite or anthophyllite schist, 
with seams of talc and chlorite, arranged in a sharply inclined or vertical 
series, with a general northeast-southwest trend. The so-called serpentine 
rock associated with these was very dark green in color, hard and much 
sheared and fractured, the fractures often containing veins of talc, marmo- 
lite, calcite, arrogonite and magnesite. The anthophyllite schist is appar¬ 
ently identical with rock struck at a depth of 200 feet in a well boring at 
Bischoff’s brewery, on the edge of the escarpment about two miles to the 
southwest, in Stapleton. 
The great variation in the character of the rock from place to place might 
seem to preclude the probability that it was all derived from one source; but 
numerous field observations and determinations of the mineral constituents 
by microscopic examination indicate conclusively, that all had a common 
origin and that this was a basic igneous rock such as an enstatite or a 
pyroxenite. 
The fact that the most extensive fracturing and shearing occurs along the 
face of the steep eastern escarpment is significant and at once suggests a 
fault as the probable cause of the escarpment. Slickensided surfaces on the 
eastern flanks of Pavillion Hill and Grvme’s Hill also strongly support this 
idea. 
Any suggestions in relation to the manner in which the serpentine should 
be indicated, in depicting a geologic section across Staten Island, would be 
welcomed. 
Dr. Julien reviewed the petrographic variation of Staten Island serpen¬ 
tines and pointed out the evidence favorable to the theory that only enstatiet 
and pyroxenite rocks were the originals from which all came. Secondary 
products are believed to indicate three subsidences and three elevations, or 
re-elevations, into the zone of weathering. A diagram showing these stages 
was exhibited and explained. A specimen of bowenite, possibly one of the 
best ever found anywhere, was shown, on which there are still preserved 
traces of the crystal outlines of original diopside. 
Much discussion was aroused by these papers over the relation of the 
serpentines to other formations and the probable structures involved. 
Remarks were made by Professor Kemp, Dr. Levison and Dr. Berkey, and 
replies by Dr. Hollick and Dr. Julien. 
