196 GEOLOGY OF ILLINOIS. 



use, just back of his house, on section 1, township 32 north, range 7 east. The 

 coal was said to be good house fuel, but rather soft ; none could be found at 

 the time of my visit. The argillaceous limestone of No. 5, of this section, 

 generally contains numerous shells of the genera Productus, Athyris, Tercbra- 

 tula, etc., and some fragments of crinoids. The coal apparently holds the po- 

 sition of the thin coal which locally underlies No. 56 of the LaSalle county 

 section. (See Vol. iii, p. 267.) 



The outcrop along the Mazon appears nearly continuous, but still I have not 

 been able to satisfy myself as to the connection of the above beds with those 

 of the lower part of the stream. The strata there developed consist of very 

 variable sandy clay shales and sandstones, in some places becoming nearly 

 pure clay shales, but containing many nodules of carbonate of iron. Pine 

 Bluff, at the lowermost crossing of the Mazon, is composed of about forty 

 feet of heavily bedded, but rather fissile sandstone, partly nearly white, partly 

 highly ferrug'nous. Less than a mile up the creek, the lower part of this bed 

 changes to highly argillaceous sandy shales, with occasional streaks and nodules 

 of sandstone. The section is not quite continuous, but there is no distinct line 

 of demarcation to separate these latter beds from the ferruginous sandy shales, 

 twenty to thirty feet thick, of section 24, of township 33 north, range 7 east, 

 which contain large numbers of the fossiliferous nodules of carbonate of iron, 

 for which this locality has become famous. Besides the many species of ferns, 

 which are named in Mr. Lesquereux's report, in this volume, the nodules also 

 contain the fossil insects, Miamia Bronsoni, M. Danse, Hcmeristia occidentalis, 

 Clirestotes lapidea, Mylacris anthracophila, Megathentomum pustulatum, Euphe- 

 merites simplex, E. gigas, E. affinis ; the Myriapods, Euphoberia armigera,, E.f 

 major, Anthracerpes typus; the Arachnids, Eoscorpius carbonarius, Mazonia 

 Woodiana ; the Crustaceans, Anthrapalsemon gracilis, Polxocaris typus, Acan- 

 thotelson Eveni, A. Stimpsoni, A. insequalis, Euproops Danse,, Eurypterus, (An- 

 thraconectes,) Mazonensis; the Worm, Palceocampa anthrax; the Salamander, Am- 

 phibamus grandiceps, with three or four undescribed Fish and Ostracoid Crusta- 

 ceans. It is thus evident that this is one of the richest deposits of Carbonifer- 

 ous Articulates ever discovered, if not the richest. 



These nodules range from about two to about ten feet above the main coal 

 seam of all this region, the intervening space being occupied by the soft, blue 

 clay shales, filled with fossil plants, which, at most points, overlie this seam. 



About a mile farther up the stream, coal has heen dug in the bed and banks 

 of the stream, but is now abandoned. Still farther south, near the southeast 

 corner of section 19, township 33 north, range 8 east, a shaft was recently 

 sunk, by Mr. Wm. Burt, upon the creek bottom, starting at about twenty-five 

 feet below the general level of the prairie. The section is as follows : 



