PREFACE
The Third Edition of the Geology of the City of New York is
much enlarged over the Second: first, through the necessary additions
of further geological studies of Manhattan Island by various
investigators, and second, through the desirable extension of the
geology of Brooklyn Borough, which is made the justification of
epitomizing the geology of Long Island.
The
mineralogical detail has been more fully given, and, in a few
expository sections, brief outlines of the Second Edition have
undergone apposite elaboration.
The
author acknowledges the courteous assistance of the United States
Geological Survey, by valuable loans of original drawings; that of the
State Geologist of New York, through his permission to copy an outline
map of a hypothetical glacial condition on Long Island, presented by
Professor J. B. Woodworth; and that of Dr. Wallace G. Levison, in the
use of plates to illustrate his unique find of Chrysoberyl on Manhattan
Island.
Recent
contributions to the geology of the crystalline rocks of southeastern
New York by Professor Chas. P. Berkey has brought into prominence views
of the ordinal position of the Manhattan rocks, substantially in
agreement with those held previously in the Second Edition of this
work, and here reiterated. These rocks, instead of representing an
ordovician and silurian placement, are referred, by that distinguished
investigator, to pre-Cambrian sediments,, which, in a chronology not
easily anywhere made certain, allies them to archaean or azoic
formations. Another moot question settled by Professor Berkey is that
of the interlamination of the limestones
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