280 GEOLOGY OF THE TfflRD DISTRICT. 



should be set free from lime, magnesia or any other soluble earth, so that their particles could 

 come together. A thermal heat would be ample, especially if accompanied by pressure, 

 which greatly favors combinations of all kind^. 



Between the two porous masses through the three gypseous counties, are the hopper cavi- 

 ties, one of the most interest relics of the group, showing that salt in a solid and crystalline 

 state existed in the group, and its position in the group. From the large size of some of the 

 hoppers, exceeding three inches in diameter, they could not have been formed upon the surface 

 of water, since in the evaporating troughs they rarely exceed half an inch, though it is pos- 

 sible that they may have been formed upon the surface of mud, which would support the 

 saline crystals ; but it appears more likely, as the hoppers are often joined six together by a 

 conunon apex, that the crystallization took place within the mass ; the single hoppers, how- 

 ever, may have been near the surface, and the others below the surface. These hoppers are 

 very abundant along Nine-mile creek, and no doubt in numerous other places : they are gene- 

 rally found in the friable part of the gypseous marl, and are readily destroyed by exposure. 

 The same kind appear at the railroad, where it crosses the road to BeUisle. The harder kind 

 are found near Syracuse in the Onondaga valley, and again on the hill to the east of Salina. 



Evidence analogous to the preceding for the existence of common salt in this group, appears 

 for that of sulphate of magnesia also. As a native salt, this sulphate generally presents itself 

 in fibrous or acicular masses. It existed in the upper part of the group, above the gypsum, 

 where numerous needle-form cavities appear, which are referable to that salt and none other. 

 The best exposition of these cavities is at Reel's and Brewster's quarry, below Jamesville ; 

 the cavities appeeiring above the gypsum ; their presence very observable from the drab color 

 of the rock, and from the cavities being coated with coal. There is another layer to be seen 

 a little higher up the creek, in which the cavities are in part filled with white lamellar lime- 

 stone. 



The general composition of this group does not differ from other saliferous deposits ; red, 

 greenish, drab and grey argillaceous and calcareous marls as they are called, forming the 

 great mass of such deposits. With these earthy materials are the gypsum and salt masses, 

 the latter sometimes found with the red portion, the gypsum usually with the hghter colored 

 products. The information which is given us of these deposits is not, however, of a very 

 precise character ; very few of the kind rising above the surface, but a knowledge of them 

 being generally obtained by wells, shafts and boring. 



The recent discovery of rock salt at Rich valley, eighteen miles north of Abingdon in Vir- 

 ginia, to which the attention of the people of this State was directed by an able article in the 

 Cultivator for September, 1841, is a fact of no small consequence to New- York ; knowing of 

 no fact which proves the gypseous or saline deposit of that valley to be different in age from 

 that of Onondaga. The relative position of the rocks in that part of the valley is obscure, 

 owing to great derangements, and rocks very different in age being brought together. I had 

 no time to seek, in the prolongation of those masses elsewhere when examining them, the 

 facts necessary to restore each part to its proper position, and thus determine the precise age 



