ROCK ISLAND ( OTXTY. 225 



city, bounded by Pleasant Valley, Rook river, and the Mississippi river, 

 is a mass of Coal Measure materials, resting upon a Devonian or upper 

 Silurian foundation of underlaying limestones. 



Building Stone. Good building stone may be obtained from tbe Ni- 

 agara and Hamilton limestones, at any of the outcrops of these form- 

 ations. They both furnish a strong, rough material for common and 

 mas-ive masonry, but are difficult to dress into good shapes. The Le 

 Clair limestone is softer and finer graiued than the beds at Port Byron, 

 but is undoubtedly only a variety of the same formation. The Niagara 

 limestone further up the river is somewhat coarser in texturer, but is 

 Mtially the same rock. The Government arsenal on Rock Island is 

 built of the Le Clair stone, but time has shown that it has not the 

 requisite solidity for such massive work, and its use is now discarded 

 in building the armory and the other public buildings in course of erec- 

 tion by the United States on that beautiful island. Some of the Coal 

 Measure sandstones would make a fair building material, but as yet 

 they have not been used extensively for that purpose. 



The other geological deposits of economical value do not differ ma- 

 terially from those found in adjoining counties, and with the exception 

 of tine potter's clay, may be passed without further comment. Associ- 

 1 with the Coal Measures about Hampton, and Carbon Cliff, and 

 doubtless at many other places along these bluffs, is a very fine deposit 

 of this clay. 



A fair sized pottery at Hampton is kept running in the manufacture 

 of common pottery ware. The clay is dug from the adjoining bluffs 

 and hauled into the village, and made into crocks and jugs. It is here 

 of a bluish, chocolate color, and makes a good article of common ware. 



But the best establishment of this kind, perhaps, in this part of the 

 State is located at Carbon Cliff, within a few hundred yards of the rail- 

 road station of the same name. Many years ago a company was formed 

 for the purpose of mining coal in the Carbon Cliff bluffs. The company 

 operated the mines, with varying success, until the coal practically be- 

 came exhausted. The fine strata of potter's clay outcropping ah" along 

 the exhausted coal seam then attracted attention. A pottery was start- 

 ed; patience, enterprise, energy and money, at last succeeded in build- 

 ing up from a small commencement a large and growing business. The 

 buildings are of brick ; the principal one is similar to a large, railroad 

 round house, with a towering smoke-stack in the center. Around this 

 has sprung up a b'ttle village, dependent for existence upon this single 

 manufactory. More than eighty hands are constantly employed. The 

 company have their own cars, which they load with their wares and at- 

 tach to the passing trains : and in this way they supply the railroad towns 

 over large portions of Northern Illinois and Iowa. Not only does this 



