MACOUPIX COUXTY. 303 



durable stone and has been used for bridge abutments and foundation 

 walls in the vicinity of its outcrop, but as the bed is only from two to 

 three feet in thickness, the supply from this source is necessarily limited. 

 This seems to be identical with the rock at the old State House quarries 

 on Sugar creek, in Sangamon county, though the bed is much thinner 

 here than at that point. The limestone over the main coal, on Hodge's 

 creek, is abundant at some points, but is too argillaceous to with- 

 stand the influences of frost and moisture, and therefore not reliable. 



Among the sandstones of this county there are at least three distinct 

 beds, that will furnish building stone of fair quality if carefully selected. 

 Two of these beds outcrop on Apple creek and its tributaries, in the 

 north-western corner of the county, and are numbered 5 and 12, in the 

 Apple creek section on page 297. These beds are 24 and 30 feet thick 

 re>peetively. and are in part composed of a massive brown sandstone 

 that stands exposure well, has an even texture and can be easily quar- 

 ried in blocks suitable for ordinary building purposes. They are more 

 or less charged with the brown oxyd of iron, which gives to the rock a 

 mottled or speckeled appearance on a freshly broken surface, and as a 

 cementing material adds much to the durability of the stone. There is 

 also a softer micaceous sandstone outcropping on the Macoupiu, below 

 the bridge, on the Alton and Chicago railroad, which affords a tolerable 

 good building stone if carefully selected. This bed' is Xo. 15 of the 

 Yirden shaft section, and lies from 30 to 40 feet below the Carliuville 

 limestone. These sandstones may probably be found outcropping 

 at other points in the western portion of the county, and, as a general 

 rule, whenever a sandstone is found to present a solid cliff of rock 

 at its outcrop, it may be safely used for all ordinary building puposes. 



Limestone for Lime. The Carlinville limestone has been already men- 

 tioned as suitable for lime-burning, making a strong but dark-colored 

 quick-lime, and it is probably the best material for this purpose to be 

 found in the county : but owing to the proximity of the purer limestones 

 of the Lower Carboniferous series at Alton, and the facility for obtain- 

 ing the very superior quality of lime manufactured at that point, it is 

 not probable that this Carliuville rock will ever be very extensively 

 used for this purpose. 



Iron Off. A band of very pure carbonate of iron was observed at 

 two or three points on the Macoupin east of Carlinville, intercalated in 

 the shales overlaying the Carliuville limestone, but nowhefe in sufficient 

 abundance to be of any economic importance at the present time. 



Clay. The under-clay of coal Xo. 4 on Hodge's creek, at the 

 single point where we found it exposed, seemed to possess the qualities 

 ot a good fire clay ; but the clays under coals Xos. 5 and 6 seemed to be 

 TOM shaly and impure to be of value for making either pottery or fire- 



