CHAPTER III. 
n- GENERAL PRINCIPLES. 
In order to a proper comprehension of the relations of the North Car- 
olina geology, by such as are not familiar with geological literature and 
nomenclature, it is needful to sketch, at least briefly, the outlines of the 
general system of geology which has resulted from the study of the rocks 
in various parts of the earth. 
The first and broadest distinction among the rocks, founded on their 
most obvious features of structure, give rise to the division of them into 
two great classes ; one, including those rock masses, in which there are 
divisional planes, more or less nearly parallel, which separate them into 
layers, or strata, the so-called Stratified Rocks , as sandstone, clay, slate, 
&c. ; the other, such as are without any such arrangement, or structural 
sub divisions, — the Unstratified Rocks , as granite, trap, porphyry, &c. 
Since granite of several varieties is the prevalent, or characteristic form 
this class, they are also designated as the Granitic Rocks ; and as a minute 
and extensive study of them discloses the fact that they are crystalline, 
and owe this constitution to the fact of their having been at one time in 
a state of fusion from heat, they are also called Igneous Rocks. And so 
the stratified rocks, being studied as to their origin, and found to be uni- 
versally formed by the accumulation of sediments, of sand, mud, &c., 
formed by the action of moving waters, as in rivers, lakes, seas, &c., are 
denominated Sedimentary Rocks. 
But many of these are also found to be much altered since their forma- 
tion, both as to position, — being often inclined to the horizon at high an- 
gles and variously crumpled and distorted, and as to constitution, being 
no longer simply consolidated deposits of sand, gravel, clay, &c., but 
more or less changed by chemical action, aided by heat, moisture and 
pressure, into a crystalline form scarcely distinguishable, in some cases, 
from the igneous rocks themselves, except by their bedding ; and even 
this is not infrequently obscured, or almost obliterated; so that they form 
a transitional term between the sedimentary and igneous rocks aud are 
called, from their altered condition, Metamorphic , and also from their 
disturbed and irregular bedding Fotyiated Rocks. 
Most of the rocks of North Carolina belong to this sub-division, — the 
granites, gneisses, &c., as do those of most of the mountain chains of the 
