Gratucap—Lozoonal Rock of Manhattan Island. 375 
The rock varies considerably in character in different places 
where it has been uncovered, and occupies a series of conical 
hills some five or six in number, distributed in a northerly 
and southerly direction. In some places, as at 60th street, it is 
taleose in structure, and may be split into thin slabs; in others 
it is dark gray, almost black, composed of straight fibers 
arranged in a columnar form, meeting and crossing each other 
frequently at right angles.” He further says, ‘it is remark- 
able that the granite lying on the west and the gneiss on the 
east of the rock in question, come in complete contact with it 
without intermixing. So remarkable is the line of separation 
on the side next to the gneiss, where there is the best oppor- 
tunity to examine the two, that within the space of three 
inches, each rock possesses all of its own peculiarities, with 
none of those of its neighbor.’ In speaking of the serpentine, 
he says, “in the same vicinity are found masses of serpentine 
and limestone intermixed exhibiting a porphyritic appearance, 
the serpentine appearing green and the limestone white;” this 
refers to the eozoonal-like portions which would seem, so far as 
their microscopic appearance goes, to easily warrant their refer- 
ence to a close relationship with the Canadian rock containing 
that debateable organism. 
Cozzens, in his Geological History of Manhattan or New 
York Island (1843), p. 12, refers to this locality, saying, ‘‘ be- 
tween 54th and 62d streets, the shore and 10th avenue, there 
are four or more small knolls of black serpentine, with scales 
of silvery or golden tale, accompanied by a vein of anthophyllite 
about twelve feet wide. This vein is in a vertical position. 
At the north end of the serpentine proper, this anthophyllite 
shows itself in two places, 7n place; one, on the rising ground, 
and near the sienite, the other at high-water mark on the shore. 
Actinolite is found imbedded in the anthophyllite. The ser- 
pentine locality commences where the granite ends. At the 
south end there is a vein of carbonate of lime. This carbonate 
of lime has many small specks of serpentine diffused through 
it, and forms a kind of ‘verd antique,’ which, when polished, 
makes handsome specimens.” 
These early observers speak of the association of the serpen- 
tine with hydrous anthophyllite, and this association points 
significantly to the origin of the serpentine itself. This bed of 
serpentine is in all probability an altered amphibole or horn- 
blende schist and the “ porphyritic,” “ verde antique,” eozoonal 
portions, the products of such, are alterations produced under 
conditions of strain and pressure, accompanied by aqueous 
infiltrations. I have not seen the vein of anthophyllite 
alluded to above, but on visiting the locality on 59th street, 
where a ledge rises up ina mound-like prominence, I found 
