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iv
PREFACE
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.