302 SKETCHES OF CREATION. 



uent, peroxyd of iron, first precipitates. This is separated 

 in the tanks before the brine is introduced into the kettles. 

 Next, after the boiling begins, the gypsum is deposited, 

 forming a crust upon the inside of the kettle. Next in 

 order, common salt begins to fall down. After most of 

 this has been crystallized out, there still remain chloride 

 of calcium and sulphate of magnesia (Epsom salts), con- 

 stituting the "bitterns" of the salt manufacturer. Further 

 evaporation would separate the Epsom salts next in order. 

 These several substances are arranged in the same order 

 in natural brine-formations. At the bottom we find red 

 clays, colored, of course, by a deposite of peroxyd of iron. 

 Next above are clays containing gypsum. In many in- 

 stances the sea-water was so clear that the gypsum was 

 deposited in pure crystallized beds, from ten to thirty feet 

 in thickness. Above the gypsum, in formations that have 

 not been leached by surface waters, we find the great mass 

 of rock-salt. Still higher are shales and limestones, con- 

 taining impressions, at least, of the needle-shaped crystals 

 of Epsom salts which were once there, but have been dis- 

 solved out by the waters which have since saturated the 

 strata. 4. The very discontinuity of the gypsum beds in 

 certain formations, as the Salina group in New York, is ac- 

 companied by such phenomena as to prove that the gyp- 

 sum was once continuous, and is being gradually dissolved 

 out. The overlying and underlying clayey beds assume 

 the place of the dissolved portions of the gypsum. The 

 remaining lenticular masses of gypsum become thus in- 

 closed by tortuous layers of clay and shale, which look as 

 if they had been primarily deposited about these masses, 

 and adjusted to them. If the overlying clay be most yield- 

 ing, the vacated space is mostly filled by an inflection from 

 above. If the underlying clay be most yielding, the inflec- 

 tion is from below. Thus abrupt loops of clay or shale 



