ONONDAGA SALT GROUP. ' 109 



deposit which takes place is the gypsum ; the third is the common salt, the magnesian salt 

 remaining in solution. The group shows first a thick mass colored red with iron, being its 

 red shale ; above which are the gypseous masses ; towards the upper part of which, are the 

 salt cavities ; the sulphate of magnesia exists above the whole of those deposits, its existence 

 there being manifested by the needle-form cavities. 



Near Syracuse, at the Hopper locality in the Onondaga valley,, and at Chittenango, &c., 

 surfaces are seen which show an angular configuration, somewhat resembling those leaves 

 whose mid-ribs are straight, and inclined at an angle of about 35° from the stem. These 

 were noticed by Prof. Eaton in his survey of the Erie canal, having seen some which were 

 thrown out in digging a well at Syracuse ; the cause of which was properly referred by him 

 to crystallization. 



On the canal near Lake Sodom, layers of a similar kind, but belonging to a lower deposit, 

 show numerous cavities not unlike those made by a small chisel of about three-fourths of an 

 inch in width ; some of them are single, and others cross each other as though struck at ran- 

 dom. In the surface also of the calciferous slate above the gypseous deposit at Grill's in the 

 town of Stark, there are small impressions in relief, the best defined of which are like obtuse 

 Indian arrow heads, being triangular, with the sides somewhat curved ; these were previously 

 noticed, but not their forms. 



Metamorphic Rock. On the Foot-street road to the east of Syracuse, between the two 

 porous masses, there is a highly interesting exposition of this kind. It appears in the side- 

 hill to the south of the road, and crosses the road, extending north for many rods. The 

 great mass of entirely altered rock is a well characterized serpentine, especially when exa- 

 mined by a microscope. The color is a very dark or blackish green, becoming yellowish 

 by alteration, a large portion of it being in a friable and decomposed state. By the aid of the 

 glass it shows innumerable points of precious serpentine, and also particles of a yellow or 

 golden color, some of which appear to be mica ; there are others of the red color of blood- 

 stone, and again some like devitrifications. It also shows well characterized mica of a white 

 or hght color, and again of a black color. In a few specimens, there was an accumulation of 

 black mica in small particles, putting on the aspect of a primary mass. One or two well 

 formed accretions of granite were found, in one of which hornblende took the place of mica, 

 forming a sienite, the mineral character perfect, the mode of aggregation also, and the 

 identity with the primary rock of like kind equally so. Some of the calcareous portions 

 showed a crystalline grain of a light drab color, beautifully veined and streaked with light 

 bluish shale, forming a handsome marble ; these and other calcareous parts formed or rather 

 existed as accretions or nodules, enveloped by the serpentine. The slaty portions of the 

 gypseous group near the altered rock, show the influence of the cause of those products, 

 being more hard and crystalline. Sulphate of strontian is one of the products also ; a very 

 beautiful specimen of this mineral was found near the hill, and is in the collection of the Syra- 

 cuse Academy. 



