ESSEX COUNTY. 221 



PRIMARY ROCKS OF ESSEX COUNTY. 

 Hypersthene Rock. 



Having given the position, relations, heights and range of the mountain cliains, in as much 

 detail as seems to be essential for the right understanding of the geological features of this 

 region, I proceed to speak of its rocks, and their distribution and mineral contents. 



In taking a general survey of this field, it requires only a glance at its physiognomy, to be 

 satisfied that the rocks belong to the primary system. This is the fact, with the exception of 

 a narrow imperfect belt of sedimentary rocks lining the shore of Lake Champlain. The 

 primary rocks break through the sedimentary masses, at the termination of those ranges 

 which have been described. The individual rocks which may be enumerated as belonging to 

 the former class, are hypersthene rock, granite, primary limestone, gneiss, hornblende, and 

 magnetic iron ore. For reasons already given, I propose to place the latter mass among these 

 rocks ; considering it, at least, as entitled to a place among the subordinate ones. 



Of those just enumerated, hypersthene is by far the most extensive and important rock 

 in Essex county. One of the most accessible points at which it appears, is in Schroon. In 

 travelling north through Caldwell and Warrensburgh, boulders are fitrst discovered to be 

 common in the latter place, so much so as to indicate that the jDarent mass is not very far 

 distant. Proceeding northwards to Schroon, it will be found that the rough hills immediately 

 west of the village are composed of this rock ; and on examination, it will appear that the 

 range of these hills forms the eastern flank of the great mass which prevails to the west, in 

 the interior of the county. Their course is northeast, towards Lake Champlain, on which 

 they finally terminate. Upon the east of these hills, the primary limestone, pursuing nearly 

 a parallel course, forms a few hills of moderate elevation ; and probably, could we trace the 

 latter rock, w'e should find it thus flanking this hypersthene chain of hills some distance to 

 the southwest. 



The most correct idea of the actual extent of the hypersthene rock in Essex county, will 

 be obtained from a statement of the towns in which it is the predominant mass. A reference 

 to the map will show the surface over which it is continuous. Thus, in the following towns, 

 it forms the basis rock : Schroon, Moriah, Keene, Elizabethtown, Westport, Chesterfield, 

 "Wilmington, Lewis, Jay, Willsborough and Newcomb. In these towns it occupies a very 

 large proportion of the surface, and in some of them the whole of it. Gneiss and primary 

 limestone range along the eastern border in Ticonderoga and the east part of Schroon, Moriah 

 and Westport. Bulwagga mountain, situated upon a bay of the same name, is composed 

 wholly of gneiss. On the extreme w"est part of Essex, too, gneiss and primary limestone 

 appear, skirting also the western and northwestern flanks of this great mass of unstratified 

 rock. In Pendleton, and in the vicinity of Newcomb lake, they form, for quite a large dis- 

 trict, the surface rock. In the central parts of the liypersthene mass, primary hmestone is 



