38 GEOLOGY OF THE SECOND DISTRICT. 



under certain circumstances, otlier limestones of a different age may contain tlie 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 srlex or alumine ? And if it is com- 

 mon, it may find its way to the surface by the same means as tlie materials composing other 

 rocks. 



Leaving here the opinions of other geologists, I will state that there are two points which 

 it will be mv- 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 equal 

 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 wc 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 farts, when they are applied to another rock. If, for example, there are cer- 

 tain phenomena in gi-anite, 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 limestone ; 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 wc are to 

 meet with more difiiculties in the determination of the questions under consideration, and 

 where geologists will be more likely to disagree. I shall, therefore, leave the consideration of 

 tlie limstoncs in these stratified rocks, and proceed to those found in certain relations with the 

 unstratified, or which arc associated with them. 



