PREFACE. 
Having been appointed by the late Governor, the Hon. William L. Marcy, 
to investigate the Geology of the Fourth District, which embraces the coun¬ 
ties just specified, my duties in that region commenced in the spring of 1837. 
The subjects of the successive Annual Reports since that time, are embodied, 
as far as possible, in the following work. A multitude of minor details are neces¬ 
sarily omitted, but it is believed that everything of economical importance has 
found a place in this Report. 
I have conceived it my duty to record my own observations, rather than to 
compile from the labors of others ; yet it has been far from my intention to 
neglect any sources of information within my reach ; and at the end of the Re¬ 
port will be found a list of those persons, so far as I know, who have written 
upon the Geology of Western New-York. 
In the commencement of the work, it was intended to confine the details chiefly 
to physical geology, and to present only a few of the most prominent and cha¬ 
racteristic fossils of each rock ; but, as there appeared some doubt whether the 
work on Palaeontology would be completed, more attention was devoted to this 
subject, and a large number of figures prepared for the work. Too little 
time, however, remained for its proper investigation, and the descriptions 
have been mostly written and the names given while the work was passing 
through the press, and it would be presumptuous to suppose that what is done 
can claim perfection. In preparing this part of the work, I have consulted all 
the authorities within my reach ; it was undertaken both for my own benefit and 
for those who wish to know something of the fossils of the New-York rocks, and 
Geol. 4th Dist. 
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