22 GEOLOGY OF THE SECOND DISTRICT. 



is propagated and conveyed down from one generation to another. The name remains, but 

 the error is either forgotten, or at least ceases to mislead. The only duty, therefore, in rela- 

 tion to those names wiiich have been so long in use, is to restrict them to certain limits. 

 This being done, we may subdivide those rocks into groups, or series, giving those names 

 to the groups, or series, which shall be derived from that section of country where they 

 arc well developed ; our nomenclature may then be completed by giving local names to in- 

 dividual rocks wliere it is necessary, observing to select those places at which they are all 

 the best developed. In following this plan, we are in less danger of overrating the value of a 

 name, or falling into error by mistaking a name for an idea, or an idea for a fact. 



I may here state that the upward limits of the Transition class may, with great propriety, 

 be placed at the Old Red Sandstone, or Old Red system, or Devonian, as it is often termed ; 

 it embraces the rocks between the primary and the old red, a limit which can generally be 

 defined with sufficient accuracy and precision. 



Adopting the names for the principal divisions of them as now proposed, I shall follow still 

 fartiier those subdivisions of the primary which have also been long in use, and which have 

 received the sanction of some of the most eminent geologists. Those subdivisions are as 

 follows : Unstratified, Stratified and Subordinate. The two first must ever remain as well 

 marked divisions, which it will be useful to observe ; the term subordinate, applies very well 

 to a class of rocks which appear irregularly among the gi-eater masses, but which are always 

 limited in extent ; and they are not found occupying the same relative position, but repose 

 sometimes upon the primary, and sometimes upon the transition, secondary, or even tertiary. 



Of the Primary Fonriations of the Northern Division of the State. 



The Primary formations occupy by far the largest part of the area between Lake Cham- 

 plain and the St. Lawrence river. They constitute not only all of that portion which is the 

 most elevated, as the mountains in the vicinity of the head waters of the Hudson, Ausable, 

 Racket, Black and St. Regis rivers, but also large tracts of the less elevated portions in the 

 immediate neighborhood of the great valleys, as the Champlain, Mohawk and St. Lawrence. 

 As a whole, or as a class, they arc well characterized ; and we find but few places where 

 there are gradations of the Primary into the Transition in this District, few rocks which can, 

 with propriety, be termed metamorphic ; they, however, present a great diversity of aspect 

 and of character, and in this respect they form an interesting assemblage of rocks. 



I have just observed, that there are few transitions of the primary into the sedimentary 

 rocks. There are, however, many transitions among the primary masses themselves ; and 

 we often find intermediate ones, which are with difficulty placed under appropriate names. 

 This is not, however, a matter of much consequence ; it is a result, or a fact, which we 

 should expect, when we consider the origin of the primary rocks, and the agencies to which 

 they have been exposed. In studying, or describing them, it is important to keep this fact in 

 mind. 



