26 THE GEOLOGIST'S TRAVELING HA^D-BOOK. 



3. The third member of the Salina formation is the gypseous deposit, which 

 embraces the great masses quarried for plaster or gypsum, consisting of two 

 ranges, between which are the hopper-shaped cavities, the vermicular lime-rock, 

 and other porous rocks. This is the most important deposit, not only on account of 

 its plaster-beds, but because it is only in this deposit that we have positive evidence 

 that salt has existed in a solid state, and, therefore, the only source whence the 

 saline springs of Syracuse could have been derived. The great mass of the 

 deposit consists of rather soft yellowish or drab and brownish colored shale 

 and slate, and of more compact masses which are hard, a brownish color 

 predominating. It is usually denominated a gypseous marl, being earthy and 

 indurated, slaty and compact. Some of it when weathered, presents a peculiar 

 appearance, as of having been hacked by a cutting-instrument, with some 

 regularity. The gypsum does not appear in layers or beds, but it occurs in insulated 

 masses, and it assumes irregular not globular forms. The dark color of the gypsum 

 is owing to carbonaceous matter. In many localities there are two ranges of 

 these masses or plaster-beds, generally separated by the vermicular rock and the 

 hopper-shaped cavities. There are two masses of the vermicular rock, the upper 

 one four feet thick, with large porous cavities, the lower one twenty feet thick, 

 with small pores. This vermicular limestone is a porous or cellular rock, resembling 

 lava. It is dark gray or blue in color, and perforated everywhere with curvelinear 

 holes, but otherwise very compact. The holes or cells vary from microscopic size 

 to half an inch in diameter, the cells being very irregular, and communicating 

 with each other, some being spherical, and the resemblance in structure to a 

 porous lava is complete. Forms which are due to common salt have been 

 discovered in this rock, showing the presence of crystals of this substance, which 

 were removed by solution. 



The most interesting products of the group are the hopper-shaped cavities, 

 which must have been produced by common salt, as no other soluble mineral 

 presents similar ones. They show conclusively that salt existed in this third 

 deposit. When salt crystallizes, a cube first makes its appearance upon the surface 

 of the brine, then similar cubes form around its border, being attached to its upper 

 surface, near the edges, while it gradually sinks, and additional particles are 

 added, forming another row of cubes upon the first range. This is many times 

 repeated, until the density of the mass formed becomes greater than the liquid, 

 when it falls to the bottom. When examined, being turned upside down, it 

 shows a pyramid of regular steps, terminated by a cube, and when its position is 

 reversed it presents a form like the hopper of a mill. Where two ranges of plaster 

 beds are seen the hoppers occur between them, and between the two massses of 

 vermicular rocks, and are from one inch to three inches and more in diameter. 

 These hopper cavities are formed hi the gypseous marl, or in the more solid parts 

 of the vermicular rock. Testaceous animals cannot live in water saturated with 

 gypsum, hence no fossils are found in the deposit. No trace of rock-salt in New 

 York has met the eye of any one, but the existence of it is a matter of no 

 doubt.* The fact of the difficulty of obtaining water in the gypseous hills, in 

 either the second or third deposit, show there is little probability of finding salt 

 above the level of the waters on account of its having long since been dissolved. 

 See Note 27, New York, as to the salt-wells at Syracuse. 



*After the above was written, rock-salt was first found, in June 1878, in a boring south of 

 Kochester. 



