138 GEOLOGY OF ILLINOIS. 



below, with 30 to 35 feet of blue clay at the bottom. The blue clay is 

 very hard and compact, and coDtaina numerous small rounded pebbles. 

 One mile south-west the railroad cut exhibits red clay, sand and peb- 

 bles at the top ; below, gray and brown beds, with alternations of beds 

 of sand and pebbles, the latter sometimes partially cemented together. 



The mound west of Vandalia has ash-colored clay at the top, and 

 darker colored clay and pebbles below ; then brown sand, pebbles and 

 bowlders ; two-thirds up the hill side there is a fine spring of pure water 

 issuing out of the brown sand. One and a half miles south-west of 

 Vandalia the river bluffs are formed of steep, broken drift hills, with 

 blue clay and bowlders at the bottom, overlaid by brown sand ; towards 

 the upper part there is a two foot stratum of ferruginous sandstone 

 passing into a hard iron ore. Its firm hard appearance might induce 

 one to think it belonged to an older age than the drift, but it lies at 

 about the same horizontal level along the hillside, and is also found 

 cropping out in other ravines at the same elevation, with drift sands 

 below. Furthermore, its frequent occurrence in this county, and also 

 in others, associated with the same drift beds, shows that it must belong- 

 to this formation. The blue clay at this place is quite hard, and the 

 water passing over it forms a tufaceous deposit on the surface. In the 

 ravines there are many fine springs of water issuing from the base of 

 the sand beds. 



On Buck creek, near the Kaskaskia bottoms, there is a dark gray clay 

 and sand conglomerate, which when struck emits a dull hollow sound. 

 A good spring of water flows from just over it, and a tufaceous deposit 

 is there formed. 



Twelve mdes south-east of Vandalia masses of ferruginous conglom- 

 erate were observed similar to that found near Vandalia. A well here 

 shows 8 feet of sand at the top, and 18 feet of sand and pebbles below. 

 In the road north of Greenland I observed — 



Ft. 



1. Buff clay and gray sandstone 5 



2. Ferruginous sandstone 4 



3. Buff clay and pebbles 4 



4. Blue clay and pebbles in sight 6 



In sec. 31, T. 6 N., E. 2 E., on the land of George Phipeb, a broken 

 stratum of coal 1J inches thick occurs in the drift, with blue clay and 

 pebbles both above and below. One unacquainted with geology might 

 imagine a permanent coal bed to be here. 



A similar place was examined on Bear creek, five miles from Vanda- 

 lia. The hill is here 27 feet high, and near the middle there is a thin 

 stratum of black sand ; beneath this are streaks and fragments of coal 

 enveloped by red sand and small bowlders, and near the base of the 

 hill there is a mass of Coal Measure fire-clay. There are also masses 

 of sandstone and limestone not much worn, all evidently drifted but a 



