CALHOUN COUNTY. 19 



easily cut, stands exposure well in a dry wall, and is a useful rock for all the 

 ordinary purposes for which a good building stone is required. Along the 

 river bluffs, and on the small streams it can be quarried very cheaply, and 

 will, eventually, come into very general use for farm buildings, fences, etc. 



Between Hardin and Monterey, several quarries have been opened in the 

 Hamilton limestone, which affords a very good material for foundation walls, 

 but the rock is much harder to work than that from the Niagara or Burlington 

 beds. On the west side of the county this rock is too thin bedded to be of 

 much value as a building stone, and, locally, becomes quite arenaceous, and 

 passes into a quartzose sandstone.. 



In the vicinity of Cap an Gres, the Trenton group, which is from three 

 hundred and fifty to four hundred feet thick, could be made available for build- 

 ing material, and the magnesian limestone, which constitutes the lowest mem- 

 ber of the series, is an evenly bedded rock, and would furnish a building stone 

 nearly, or quite equal to the dolomites of the Niagara group. From the favor- 

 able position of its outcrop, near the top of the Cap au Gres bluff, extensive 

 quarries could be opened at this point, at a very moderate expense, and the 

 rock could be transferred directly on to lighters or barges, and towed to any 

 point on the river where a good building stone was in demand. 



Below the Cap au Gres axis, the St. Louis limestone is the prevailing rock, 

 and forms a continuous limestone cliff along the river to the old town site of 

 Milan, the termination of the bluffs on the Mississippi, in this county. This 

 limestone makes a very durable building stone, but is much harder than the 

 magnesian limestones of either the Trenton or Niagara groups. It is, for the 

 most part, a thin bedded, light gray limestone, but contains some layers thick 

 enough for dimension stone, and the outcrops in this county would furnish an 

 inexhaustible supply of building stone of a fair quality. 



Limestone for Lime. The best material for the manufacture of quick lime 

 in this county, is supplied in great abundance by the St. Louis limestone, 

 which may be made available for this purpose at almost any point where it out- 

 crops along the river, for a distance of more than twenty miles. Some beds in 

 this formation, however, are arenaceous, and contain too great a proportion of 

 silicious or argillaceous material, to be readily converted into lime, while others 

 are a nearly pure carbonate of lime in their composition, and make a very pure 

 white lime. The outcrop of this formation for so great a distance along the 

 river, in the most favorable position for carrying on this branch of manufac- 

 tures, renders this one of the most eligible points on the river for prosecuting 

 this business on a large scale. The kilns could be constructed so near the 

 river, that the manufactured article could be readily transferred on board 

 steamboats, or barges, thereby saving all expense of land transportation ; and 

 the overlying coal beds, which outcrop in close proximity to the limestone, 



