18 Geology of Peoria County. 
We find a bed of fire clay immediately under each coal seam. Was it from 
that source the plants derived their nourishment? 
Fire clay is an aluminum silicate, which contains very little food for plants. . 
It was doubtless the fact, that these beds were our common clays, contain- 
ing the nitrates, and other nutrient elements which supplied the plants. The 
thousands of years during which the forests stood upon this clay, taking from 
it these elements, left only those portions, of which they could make but 
little use, namely, the silica and aluminum. Hence, the fire clay. 
We have in this county, nine separate coal strata, in which we find all their 
characteristics. Nos. 1, 2, and 3 have not as yet been worked. No. 4 fur- 
nishes most of the coal we use at present. No 5 is nearly altogether wanting 
in coal. There isaseam of it of narrow extent, twelve to eighteen inches 
thick, on Section 24, Limestone township. No. 6 has been used quite exten- 
sively. It is much freer from earthy impurities than No. 4, is softer, and bet- 
ter for the blacksmith’s use. From No. 7 was taken, all the coal used, in the 
western parts of the county for many years. Nos. 8 and 9 have afforded no 
coal (unless a little said to be from No. 8 in the northeast part of the county) 
perhaps from the fact, that they had no clay, from which arboral growths 
could be sustained. | 
A bed of No. 9. in the horizon in which we should find it, lies near the sur- 
face of the prairie on the N.W. quarter of Section 2 in Kickapoo township. 
A bed of two or three feet in thickness, of soft, shaly, argillaceous limestone; 
rich in fossils, of which the Athyris subtilita, Spirifer camerata, and Myalina 
angulata largely predominate; these and many others are taken out in a very 
perfect condition. This lies upon a gravel bed, several feet in depth, in which 
are found also the,same species. 
The variations in the thickness of the coal seams, indicate variations in the 
conditions under which they were formed. There may have been, for instance, 
but a few acres in extent, that had all the conditions necessary for the full 
development of the forest growth. Surrounding, or by the side of this forest 
field, the grounds may have been too high, or too low, or other causes may 
have existed, which prevented its full growth. Hence a thinner bed. 
We have now arrived at the top of the geological column. We have passed 
twenty-eight distinct strata. Fourteen of these belong to the carboniferous 
series. We have had in review the formation of the rocks; have hada 
glimpse of the first life that appeared upon the earth, and observed its 
progress in after ages; we have seen the carbon which loaded the atmosphere 
taken from it, and stored away in the coal beds to be preserved for the uses of 
man in the future; we have seen the wonderful flora, which was instrumental 
in accomplishing this work, and by which meang the air was purified and 
made fit for the use of air-breathing animals. And finally, have seen with 
delight the varied and beautiful fauna which inhabited the seas, the remains 
of which, though mute, speak loudly of the history of their generations. 
They have been also the recording pens which traced upon the rocks in graphic 
lines, their history, to be read by man in long ages subsequent. 
Our habitation is upon ancient grounds. Long ages, after our last sub- 
mergence, when our highest rock stratum was formed,—long after we became 
dry land, the states of New Jersey, east Pennsylvania, Delaware, eastern 
Maryland and Virginia, North and South Carolina, Georgia, southern Ala- 
bama, Mississippi, Louisiana, west Tennessee and Kentucky, most of Texas, 
Indian Territory and Kansas, eastern Colorado and Wyoming, Nebraska, 
Dakota,, extending northwest to the Arctics, and western California, were 
many times under the waters. 
While our land laid in the grandeur of its silence, except the chirping of a 
few pterodactyloid birds, and the dissonant voices of the batrachian reptiles, 
the waters covering these areas were alive with enormous reptiles. The bel- 
