186 
GEOLOGY OF THE FIRST DISTRICT. 
“ The next most common and widely spread boulder, is what is called Esopus millstoner 
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, 
completely 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 eflbrts and industry of man, even when aided by gun¬ 
powder ; 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 color 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 siliceous cement. In a few, iron pyrites exist 
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 stratum 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 mistaken. Ano¬ 
ther stone which has attracted some attention in the county, is the lahradorite. Its existence 
was first noticed by Dr. Heron, of Warwick, several years since. In. addition to Warwick, 
I have seen it the present 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 been polished, 
and prove very fine. They usually reflect only the green and blue colors. The best I have 
seen is in Warwick ; also in Walkill, upon the farm of Dr. Shaw; and in Blooming-Grove,, 
upon the farm of Joseph Moffat. 
“ Many other erratic stones are found, not deserving particular notice; but it should be 
remarked, that wherever transported fragments of a rock are seen in the county, they are 
always to tlie southward of the parent rock. Thus, from the south end of Mount Eve, 
a chain of blocks can be traced for miles, even into New-Jersey, of a character so peculiar 
as to render mistake impossible. Another stone found in rolled masses, in the county, is 
jasper. They are yellow, striped, red and black. Many of them contain cavities, lined with 
small but beautiful quartz crystals, and coatings of white, blue and yellow calcedony. Some 
of the jasper boulders are coarse, some fine and compact, some slaty, and some ferruginous. 
