reOCERE DINGS 
OF THE: 
NATURAL SCIENCE ASSOCIATION 
OF 
VoL. VII. No. ‘13. 
The regular meeting of the Association 
was’held at the residence of Dr. Artbur 
Hollick, New Brighton. 
In the absence of the president Mr. J. 
Biake Hillyer°was elected chairman pro 
tem. 
Dr. Arthur Hollick exhibited speciinens 
recently collected and read the following 
“GEOLOGICAL NOTES. 
Decomposed serpentine and associated 
minerals. In’Mr. LP. Gratacap’s paper, 
publisbed in the, pre eding issue of our 
Proceedings, mention is made of an-ex- 
posure of serpentine, near the old limon- 
ite mines, in a cutting on Ocean Tertace 
road. A similar cut has recently been 
made in regrading the Todt Hiil read 
near Moraviarn cemetery, which has ex- 
posed a five section through the decom- 
posed upper portion of the serptntine, 
and.as this locality is outh of the moraine 
the rock has not been disturbed by glacial 
action nor has the’surface soil been mixed 
with drift deposits. Every stage in rock 
disintegration and soil formation én situ 
may be trated, from the merely fractured 
rock at the base, through that which is 
partiaily disintegrated, to that in which 
the disiutegration is complete and the 
rock is represented by the surface soil. 
The minerals which have resulte] from 
this decomposition are particularly con- 
spicuous and excelleut specimens uray be 
obtained with but little trouble. Green 
chiorite and white talc in bands or seams, 
orin finely comminuted particles massed 
tegether like ‘clay, ‘alternate with red, 
brown and purplish limonite in irregular 
STA TEN 
ISLAND. 
JANUARY 13th, 1900. 
patches or pockets, the series resting upon 
utidecomposed serpentine below and 
covered by limonite soil above. 
The derivation of the latter from the 
former inay’be traced frony the unaltered 
chronrite or magnetite iu the serpentine, 
to where these minerals occur as browu 
specks of limonite where the rock has be- 
come talcose or’chloritic, and finally to 
the zone of coniplete disintegration, where 
the limonite*has become segregrated into 
seats or pockets, while the rock is repre- 
sented by incoherent accumulatious or 
loose flakes’ of talc and chlorite. The 
pockets in which the limonite occurs ap- 
pear to be merely irregularities in the 
serpentine due. to decomposition by the 
ordinary atmospheric agencies at the 
points of easiest attack. They are nar- 
row below, often extending downward 
into’a thin seam along a joint or fracture 
and are broad’ above, so that the Jimonite 
asa whole consists of a series of irregu- 
larly wedged-shaped masses in its lower 
part, which merge into and forma con- 
tinuous bed at the surface. 
Joints and fractures in the serpentine 
appear to have been the initial lines of 
oxidation, down and from each side of 
which the process gradual'y extended, 
thus forming the wedge shaped pockets 
and leaving an irregular surface on the 
undecomposed rock. 
So far as this locality is concerned all 
the facts indicate that the limonite was 
solely the result of decomposition of the 
serpentiue in’ place, and the oxidation of 
the included ‘chromite or magnetite by 
the ordinary atmospheric agencies. 
