SOMETHING ABOUT ROCK-SALT AND GYPSUM. 305 



vey, of which this was but one of the results, cost the state 

 five thousand dollars. The discovery of brine in the Sagi- 

 naw Valley has added two millions of dollars to the capi 

 tal of the state. 



The next conspicuous salt formation in ascending order 

 is the Coal-measures. The reader who recalls the surface 

 conditions under which the coal was formed will at once 

 perceive that there must have been a great concentration 

 of sea-water in the remote and somewhat isolated lagoons 

 and marshes in which much of the materials of the coal 

 formation were accumulated. It will be noticed, also, that 

 the associated strata are here, as elsewhere, predominantly 

 argillaceous. As the Coal-measures are universally under 

 laid by the great Conglomerate, this becomes the reservoir 

 in which the saline solutions from the Coal-measures accu 

 mulate. The Conglomerate is the &quot;salt-rock&quot; of Ohio, West 

 Virginia, and Northeastern Kentucky. It also underlies a 

 large central area in the peninsula of Michigan, and thus 

 constitutes the third -great salt basin within the limits of 

 that state, each underlying the same central area. The 

 shallow wells at Bay City, Portsmouth, and the Lower 

 Saginaw River generally, are supplied from the Conglom 

 erate. The deeper ones at the same places are supplied 

 from the next basin below. The gypsum is generally dis 

 solved out of the Coal-measures, but in Western Iowa it 

 still exists in vast quantities. 



In Southern Kentucky, and Northern and Central Ten 

 nessee, brine is obtained by boring into the &quot;Silicious 

 group&quot; a local name for certain members of the Moun 

 tain limestone. I will not attempt to decide whether this 

 brine proceeds from the Coal-measures or the False Coal- 

 measures, or has had an independent origin. 



In Texas, Colorado, and Kansas, salt and gypsum are 

 supplied in vast quantities from formations of Mesozoic 



