38 
GEOLOGY OF THE SECOND DISTRICT. 
under certain circumstances, other limestones of a dilferent age may contain the same mine¬ 
rals. I have reference, of course, to those limestones which have been considered metamor- 
phic, in relation to which I shall have occasion to speak before I have finished what I have to 
say of this rock. 
. As the views taken of this rock, and which were given in the report for 1838, remain un¬ 
changed, I now propose to place before the reader a full account of the observations and facts 
which led me in the first place to entertain the opinions and doctrines in the report referred to. 
The opinions of geologists in relation to the origin of limestone, have been hitherto unset¬ 
tled. From the great amount of limestone in the strata which may be inspected, it has been 
supposed that animals possessed the power of forming it, or of combining its elements. This 
view or theory seems to be wholly unnecessary ; for what reason have we to infer that it is a 
material less common in the interior of the earth than silex or alumine ? And'if it is com¬ 
mon, it may find its way to the surface by the same means as the materials composing other 
rocks. 
Leaving here the opinions of other geologists, I will state that there are two points which 
it will be my object to establish: 1st, That it is a rock of igneous origin ;■ and 2d, That it is 
unstratified, which follows from the establishment of the first point; or if the last proposition 
is placed first, viz. that the rock is unstratified, its igneous origin seems to follow with ecpial 
certainty, so that the points to be proved are really reduced to one ; unless, indeed, it can be 
shown to have been originally a stratified rock, and subsequently, by internal heat, the planes 
of stratification were destroyed, or in other words, that it is a metamorphic rock. 
Before we proceed to the consideration of the phenomena which bear upon the questions 
proposed, I remark, that in reasoning upon phenomena and facts, we should give them a 
general construction ; that is, if the inferences we draw from them are correct in a given case, 
or when applied to a certain rock, then we ought also to accept the inferences from the same 
phenomena and facts, when they are applied to another rock. If, for example, there are cer¬ 
tain phenomena in granite, which go to prove its igneous origin, then the same phenomena 
prove the igneous origin of any other rock in which they may be observed. It is by this mode 
of procedure that I propose to establish the igneous origin of this liniestone ; following out 
the train of reasoning by which Hutton has proved the igneous origin of granite, and the great 
mass of unstratified rocks. It is applying the same mode of reasoning to a limestone, which 
has been approved of in the case just cited ; and I can see no reason why the principle is not 
correct and safe : it is one of the modes by which truth is to be finally established. 
All the geologists of this country agree in one fact, that a coarse limestone occurs among 
the primary masses. In the New-England States, this rock is met with very frequently 
among the strata of gneiss, hornblende, mica, and talcose slates. It is among these rocks 
that it puts on the appearance of a stratified rock, if any where; and it is here that we are to 
meet with more difficulties in the determination of the questions under consideration, and 
where geologists will be more likely to disagree. I shall, therefore, leave the consideration of 
the limstones in these stratified rocks, and proceed to those found in certain relations with the 
unstratified, or which are associated with them. 
