PREFACE. 
IX 
will be found to commence in the Quaternary formation, more fully entered into 
in the Drift deposits, and more or less continued through the Upper secondary. Coal 
and other Fossiliferous and Sedimentary strata to the Potsdam sandstone. At the 
meeting of the Association of American Geologists at Philadelphia in 1840,1 was 
appointed to make a communication at the next annual meeting, on the ''Drift” 
At the next meeting the labor taken in hand was not completed, but a glimpse of 
light was believed to have been perceived that would lead to an explanation of 
the phenomena of the “ Drift,” Leave was asked and obtained to defer the com¬ 
munication another year. Unexpectedly to me, I could not attend the two next 
succeeding meetings, and the paper on “ Drift” intended to have been brought 
before the Association in 1842, but enlarged and more fully discussed, now first 
comes before the public in this work. Numerous facts in detail are introduced 
to show the grounds for the conclusions, some of which are believed to be dif¬ 
ferent from any that have been broached. Time and investigation will show 
whether they are well founded. Nearly all the phenomena of physical geology 
may, it is believed, be referred to the effects of three causes, viz: 1, Caloric; 
2. Gravitation; 3. Centrifugal force of the earth revolving on its axis. 
The explanations of blowing caves and of ebbing and flowing springs, are 
original and believed to be new. Various subjects are discussed under new points 
of view, but to which it is unnecessary to call the attention, as those who would 
be interested in such things will necessarily find them. 
To Mr. Patterson, the careful proof reader, I here return my thanks. He 
has relieved me from almost the entire labor of corrections. It is only by an 
accurate knowledge of the subject, and great and continued vigilance and care 
that the work could have gone through the press with so few errors. 
While engaged in the operations of the geological survey of New-York, I have 
met with cordial cooperation every where, among all classes of the community, 
and but a single isolated instance has occurred where we were molested in our 
labors, and that through ignorance.* It would be invidious to mention a few of 
the gentlemen who have aided us by their local knowledge of facts and pheno¬ 
mena, where so many are entitled to our thanks. 
* This was while procuring specimens from a boulder on Long Island, that had been removed from a field of the 
adjoining farm into the road. The owner, thinking there must be gold in the stone, from our preserving the specimens 
with so much care, and wrapping them in papers, directed the collectors to desist; but as it was in a public road, we declined 
to do so. 
