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GEOLOGY OF THE FOURTH DISTRICT. 
CHAPTER XII. 
SUPERFICIAL DETRITUS. 
The superficial materials covering the surface of the older stratified rocks of the Fourth 
District, and to a great extent concealing them from view, are due to successive operations on 
a more or less extended scale, which have broken up the indurated strata, and worn the frag¬ 
ments to different degrees of comminution. The agencies producing these effects have been 
sometimes almost universal throughout the extent of this district, and at others confined within 
very limited areas ; and we may trace them through successive stages from the simple opera¬ 
tions of freezing water, the running of streams and rivers, the washing of waves upon the 
lake shores, through more stupendous exhibitions, as the damming up of river channels, the 
excavation of new ones, the bursting of lakes, etc., till the phenomena pass beyond our means 
of comparison, and leave us to conjecture in what manner these have resulted, as they trans¬ 
cend the usual effects of causes before our eyes. These more extensive and least known 
operations have produced those deposits of loose materials, sometimes called diluvium; but 
as this term includes many deposits of local or very modern origin, the term drift has been 
proposed, as being unobjectionable in this respect, and unambiguous in its meaning.* 
The scoring and striating of the surface of the strata, which seems to have been effected at 
the same period, as well as the excavation of broad and deep river channels, and the like, are 
all referred to an agency concerning which there is yet no settled opinion. The plausible 
theories of one observer are modified or overturned by new facts, or the bolder speculations of 
another; and at this moment, even the most extravagant hypotheses are advanced in order to 
account for these familiar phenomena. 
While so many conflicting hypotheses are thus before the public, it would be of little mo¬ 
ment to advocate the one or the other; and therefore the facts observed in the Fourth District 
will be stated, with the unavoidable conclusions to which they lead. There is always, in 
these investigations, great need of caution, not to confound the products or the phenomena of 
two or more periods; fol - it can readily be demonstrated that the superficial deposits of the 
State are of different ages, sometimes distinct and separate, and again mingled and confused. 
No one theory of formation can account for the whole, and we are therefore often to seek for 
causes close at hand, rather than venture too far into conjecture.! 
* See Murchison’s Silurian Researches, page 509, note. 
t Mr. Murchison has very clearly shown the successive periods in which the superficial accumulations of certain parts of 
England and Wales were produced ; and the facts observed in New-York correspond precisely with his views and observations. 
