6 
PREFACE. 
In prep&.ring this report, I have in reality drav/n it up in two parts, though this 
is not distinctly stated. The first part embraces a general description of all the 
rocks, accompanied with an illustration of many of the principal phenomena 
which they disclose. In the second part, or the geographical division of the 
work, I have noticed the peculiarities which are furnished in different parts of 
the district. In consequence of this method, I may sometimes have been too 
minute in drawing up my description, and may have repeated the same fact in 
several places. 
It becomes necessary to notice, in this place, what may appear as discrepan¬ 
cies of some parts with others, particularly in relation to the nomenclature. I 
proposed the words Neiv-York Transition Systein, as the name by which the 
rocks should be designated. I had previously used the same term ; and in fact, 
having a predilection for the word transition, I early proposed the above desig¬ 
nation for the New-York rocks. Subsequently it was proposed to strike out the 
word transition, leaving the simple appellation. New- York System, which, being- 
shorter, I considered a better name, and hence it was adopted and generally 
used ; but this change was not proposed until the whole of my general account 
of the rocks was printed. Other changes, too, have been made in the progress 
of the work, not contemplated in the commencement: several illustrations have 
been added, particularly the wood-cuts of some of the characteristic fossils, which 
were not determined on until too late to employ them in the general description 
of the rocks. 
Without attempting to sum up all the results of the Survey of the Second 
District, I may with propriety state generally, that the rocks, their relations and 
mineral contents, have been determined over an area of ten thousand square 
miles; and their geographical boundaries, lithological and paleontological cha¬ 
racters, have been ascertained wdth great exactness. That many interesting 
facts, however, are yet to be discovered, I have no doubt. The field, in fact, 
may be considered as only now prepared for investigation, or opened for a more 
successful exploration; and I hope yet to be able to complete a series of obser¬ 
vations, which I have had opportunity merely to commence, particularly those 
in relation to drift and diluvial action, as well as others in relation to the presence 
of ores. 
In rendering acknowledgements due to those who have promoted the objects 
of the Survey, they are due first to both of the Chief Magistrates who have suc¬ 
cessively filled the Chair of State during its progress, not only for official acts 
