with the schists, which also corroborates a provisional claim previously made in these pages.
With
the disappearance of the topography or, at least, the removal of
shallow superficial features of Manhattan Island, through building and
construction, the opportunities for geological study, and especially
for mineralogical examination, grow sensibly less. A record, then, of
the known investigations in these subjects has a timely relevancy, at
the moment when such investigations must be summarily curtailed. At the
same time hitherto inaccessible areas have been reached, by reason of
the excavations, tunnelings, caisson sinkings, soundings, etc., which
accompany the new engineering enterprises on the Island of Manhattan,
and elsewhere, within the limits of the greater city. The conclusions
drawn from the additional knowledge gathered from such undertakings
demand, too, a popular interpretation and currency, and, from its
retreat or sepulture in technical treatises and proceedings of
societies, the information, carefully collected by scientific
observers, consciously craves, we might say, greater popularization.
The
facts presented and the statements made have been brought together from
many sources and are carfully classified, and the book will, it is
hoped, helpfully develop and complete a correct geological conception
of Greater New York.
