68 
GEOLOGY OF THE SECOND DISTRICT. 
do not preserve lithologically a unity of character: the one is a mixed or compound rock, 
and described as being composed of certain minerals ; the other as a homogeneous mass ; yet 
the former is not composed always of the same elements or minerals, nor is the latter always 
a homogeneous rock. These remarks are made in consequence of having observed a remark¬ 
able variation in the characters of serpentiije in the Northern District of New-York, from those 
which belong to Massachusetts and the other New-England States ; and I may go farther, 
and say that some remarkable differences appear in the same rock, though in the same neigh¬ 
borhood, as will be seen in the sequel. 
Serpentine is usually green, variegated with spots, deep or pale, and often beautifully mot¬ 
tled. The green is the most common color; still it is sometimes brown, red, yellow, and 
veined with substances of different colors. So, upon the whole, it presents an unusual com¬ 
bination of characters. It is also one of the most close grained and compact rocks we have. 
That variety which is associated in New-York with limestone, is usually perfectly compact 
and translucent; that which occurs in the iron ore beds, approaches to a shaly or shivery 
mass. Other beds, in other sections of country, as those of Middlefield and Chester in Mas¬ 
sachusetts, are finely granular, quite opake, and mostly uniform in color. Varieties with 
still greater differences are found, some of which are brecciated, as those, for instance, which 
underlie and penetrate in various ways the beds of peroxide of iron in Jefferson and St. Law¬ 
rence counties. This curious and interesting variety contains angular pieces of quartz, from a 
tenth to half an inch in diameter. Generally they appear closely invested with the serpentine ; 
but sometimes they may be removed, and in fact fall out of their own accord by disintegra¬ 
tion. The masses of quartz are angular, and show no appearance of being incorporated with 
the rock ; for this reason, it is quite difficult to offer a satisfactory solution of the question of 
the origin of this quartzose serpentine. 
There has been much discussion of the question of its stratification, and there are able 
geologists enlisted on both sides. Macculloch and Prof. Hitchcock maintain the doctrine that 
it is often at least a stratified rock, and Prof. Hitchcock goes so far as to give the dip of the 
strata ; but having often examined the locality in Middlefield, the one referred to by the Profes¬ 
sor, I have never been able to satisfy myself of the fact itself.* I am sensible that serpentine 
is often in splintery or shivery masses, putting on somewhat the appearance of a shaly struc¬ 
ture ; yet I have not regarded it at all as due-to stratification, or even a tendency thereto. The 
same splintery sharp-edged variety occurs in the ore beds of the north ; and often these sharp 
pieces are striated, as if rubbed against each other, and it appears to be analogous to the glazed 
slate in the Champlain groups, which I have supposed to have been pressed strongly when 
in a yielding state, and perhaps elevated at the same instant. So serpentine, after a consolida¬ 
tion at numerous points, might be exposed to pressure ; and when forced upwards, the harder 
masses would slide upon the softer ; and by this movement, they would receive those impres¬ 
sions, or stria, which appear on those glossy surfaces termed slickensides, and at the same 
time give them that splintery sharp-edged condition in which we now find the mass. 
Hitchcock’s Geological Report of Massachusetts, Vol. 2. p. C16. 
