160 
[Assembly 
rock of the former is to be sought for beyond the bounds of the county, 
but where, has not fallen under my observation. 
The next most common and widely spread boulder, is what is called 
Esopus millstone, and white flint rock, or the millstone grit of Prof. 
Eaton. These are found abundantly over all that part of the county 
between the mountains. They are, almost without exception, com- 
pletely rounded — -none are flat or angular. They are evidently more 
numerous, and much larger in the northern than in the southern towns. 
In Montgomery and Crawford, they are often too large to be removed 
by the efforts and industry of man, even when aided by gunpowder; 
some may there be seen of five hundred tons weight, and probably 
much more. As we proceed south, they gradually diminish in size and 
frequency. How far they extend, I am unable to say, but I have seen 
them near the New- Jersey line. These boulders are pretty uniform in 
appearance; their colour is white, bluish, or reddish-white. It is seldom 
compact, but generally composed of grains and pebbles from the size 
of small peas to that of white walnuts, and sometimes much larger; 
some of the pebbles are smooth and rounded, others are angular — 
nearly all are united by a silicious cement. In a few, iron pyrites ex- 
ist as the cementing substance, or disseminated through the mass; this 
decomposes when exposed by a fresh fracture, and gives the rock a 
greenish appearance. 
From what has been stated, I think these masses have been brought 
into the county from the north by the agency of water. A rock stra- 
tum is seen in Blooming-Grove, precisely similar to the boulders just 
described, but this is shut in by two elevated primitive ridges, and its 
fragments have had a limited distribution, and can be readily traced to 
its limit within the county. Boulders of the same millstone grit, and 
of the same appearance and character, are also found in the valleys of 
the Neversink and Delaware, but these can also be traced to a stratum 
in that vicinity, whose fragments have taken a direction not to be mis- 
taken. Another stone which has attracted some attention in the county, 
is the lahradoriie. Its existence was first noticed by Dr. Heron, of War- 
wick, several years since. In addition to Warwick, I have seen it the pre- 
sent season in Goshen, Minisink, Walkill, Hamptonburgh and Blooming- 
Grove. No doubt if sought for, it might be found in many other places; 
it is found in pieces weighing from a few pounds up to three or four tons. 
They are all rounded, and very much worn, having the appearance of 
travellers from afar. No rock formation of this kind is now known to 
exist nearer than Essex county. Some pieces of these boulders have 
