: MANHATTAN ISLAND 89
limestones are to be included, but it also may be instantly ad-mitted that the weight of authority is against this view. In a general sense the Archaean may include everything pre-Cambrian.
This
is an old view—and is disparaged because it is old. It has more
recently been assumed that the crystalline schists of New England—much
of them—the schists of Southern New York, those of Philadelphia,
Baltimore, Washington, and Richmond, belong to the sedimentary series,
in which all traces of fossils, if they formerly existed, have become
obliterated through metamorphism. The Fordham gneiss of the Bronx,
bordering the Harlem River, and on Manhattan Island at I52d Street, is
frankly conceded as archsean or pre-Cambrian, and it is permissibly
deduced that the gneiss rock brought up from deep borings on Manhattan
Island is also Fordham gneiss or archaean. The Manhattan schists—
gneisses and mica rock—overlying are referred to the Hudson River
formation, and represent the metamorphosed shales or slates of the
Hudson River beds, according to the authoritative view of the Albany
geologists. It may be suggested, however, that there are no rocks
certainly referable to the Hudson River formation south of the
Highlands in New York —which are unquestionably Archaean—and the progressive metamorphism must
be traced through the schists of Connecticut to the New England
taconic slates and shales, while from a Iithological point of view it
appears unusual that andalusite should not occur more frequently in the
Manhattan schists as a metamorphic sequelae from altered slates, of
which it is so highly characteristic. Rosenbusch has pointed out that
it occurs far more rarely in the mica-schists and gneisses of the Archaean.
Professor
Chas. P. Berkey, of Columbia University, has exhaustively studied the
crystalline belt of rock from New York City to the Highlands proper,
and his study, by reason of its exhaustiveness (under natural
limitations), its care and discrimination, and the poise of judgment
in its author, perhaps
