SAXGAMOX COUNTY. 



This coal seam, numbered 11 in the general section given on a prece- 

 ding page, ranges in thickness from eighteen inches to two feet, and is 

 coal Xo. 8 of our general section of the Coal Measures given in Vol. Ill, 

 page 5, of these reports. It outcrops in the bank of the Sangamon river 

 at Howlett. and on Spring creek and its branches north and west of 

 Springfield ; and previous to the discovery of the heavy beds below this, 

 it was extensively worked in strip banks, and by tunnels along its line 

 of outcrop. It is overlaid by a calcareous shale, and argillaceous lime- 

 stone, which are wonderfully rich in fossils, and have afforded more than 

 sixty species of the shells, corals and criuoidea characteristic of the 

 upper Coal Measures. The coal is underlaid with a dark bluish-gray 

 fire-clay two or three feet in depth, below which an impure nodular lime- 

 stone is sometimes found, but more frequently the fire-clay res^s directly 

 upon the sandy shales and sandstones below. At Howlett, the argil- 

 laceous limestone overlaying this coal seam is succeeded by sandy shales, 

 passing upward into soft inicacous sandstones, which outcrop along the 

 railroad grade just beyond Camp Butler, and contain an intercalated 

 seam of poor coal, only a few inches thick. The limestones of Sugar 

 creek, which properly overlay this sandstone, are not found in the vicinity 

 of Howlett, having been probably removed in the erosion of the Sanga- 

 mon valley. 



Below this coal where it outcrops west of the city, we find a bed of 

 sandy shale and sandstone from thirty to forty feet thick, that locally 

 furnishes some building stone of fair quality, the thick bedded portions 

 being partly concretionary in structure, the concretions often attaining 

 a diameter of five or six feet or more. They are exceedingly hard but 

 may be split into blocks of suitable size, and make a very durable build- 

 ing stone. 



At Carpenter's mill, five miles north of Springfield, a fine exposure of 

 the sandstone underlaying this coal may be seen on the north bank of 

 the Sangamou, where it forms a perpendicular cliff more than fifty feet 

 in hight. The upper and lower portions of the formations are thin bed- 

 ded and shaly, but the middle portion, nearly twenty-five feet in thick- 

 ness, is in tolerably heavy and evenly stratified beds, ranging from six 

 inches to two feet or more in thickness. These thick layers seem to 

 harden on exposure and afford a very good building stone. 



In a ravine a little to the west of the road on the north side of the 

 river, the coal Xo. 11 of the foregoing section, and overlaying argillaceous 

 limestone were found well up towards the top of the hill, and apparently 

 above the sandstone exposure at the bridge. The limestone here contains 

 the same species ot fossils so abundant in the roof of this coal in the 

 vicinity of Springfield. The coal was not well exposed, but does not 

 appear to be more than a few inches in thickness, and this exposure is 



