70 



PENNSYLVANIAN SPORES OF ILLINOIS 



of the Tradewater group and many guide 

 fossils are present. Eighteen species of 

 small spores appear restricted to the coal 

 beds of this group. The genus Denso- 

 sporites is not known to occur in coal beds 

 of post-Tradewater age in Illinois. Wil- 

 sonia gen. nov. has not been seen in the coal 

 beds examined of Tradewater age, but does 

 occur in the older Carbondale and Mc- 

 Leansboro coal beds. The genera and 

 species distribution is illustrated in chart 1 

 (in pocket). 



CARBONDALE GROUP 



The Carbondale group includes the strata 

 from the base of the Palzo sandstone to the 

 top of the Herrin No. 6 coal bed in south- 

 ern Illinois, and from the base of the Isabel 

 sandstone to the top of the Herrin No. 6 

 coal bed in western Illinois. The Carbon- 

 dale group is thought to correlate with the 

 middle third of the Des Moines series of the 

 Midcontinent (Cooper, 1946), and with 

 the Westphalian C of Europe. The thick- 

 ness of the group does not exceed 400 feet 

 according to Weller (1945), and in many 

 places is much less. It is characterized by 

 three persistent coal beds, the Nos. 2, 5, and 

 6 which are known to be present in south- 

 ern, central, and northern Illinois. The dis- 

 tribution of the No. 4 coal bed is less exten- 

 sive than these beds, and the 5-A coal bed 

 is essentially restricted to southeastern 

 Illinois. 



In contrast to the Tradewater group, 

 limestones are more prominent and there 

 appears to be considerable similarity in the 

 succession separating successive coal beds. 



No. 2 Coal Bed 



The type locality of the Colchester (No. 

 2) coal bed is at Colchester, T. 5 N., R. 4 

 W., McDonough County. The No. 2 coal 

 bed in northern Illinois has been called the 

 LaSalle No. 2, or Third Vein, coal bed. 

 In southern Illinois, a thin, more or less in- 

 definitely located coal bed above the Palzo 

 sandstone has been correlated as the No. 2 

 coal bed by Wanless (1939) and by Weller 

 and Wanless (1939). 



The Colchester (No. 2) coal bed of 



western Illinois and LaSalle (No. 2) of 

 northern Illinois are a continuous bed and 

 the same spores are found in both areas. 

 A coal bed 2 feet 8 inches thick from a 

 diamond-drill core in Franklin County, sec. 

 27, T. 6 S., R. 2 E., at a depth of 789 feet 

 is identified as the No. 2 coal bed on the 

 basis of its spore content. The following 

 is a generalized description of the coal beds 

 and other strata encountered in the Carbon- 

 dale group of this core : 



Depth Depth 



Ft. In. Ft. In. 



Base of McLeansboro.638 10 

 Top of Herrin (No. 6) 



coal bed 638 10 



5-A coal bed 665 5}^ to 665 iy 2 



Top of HarrisbursJ 



(No. 5) coal bed. .. .685 



No. 4 coal bed (?) 766 10 to 767 8 



No. 2 coal bed 789 to 791 8 



Bone and shale 791 8 to 792 2 



Pyritelens 792 2 to 793 3 



Underclay 793 3 to 794 11 



Siltstone 794 11 to 802 



Sandstone (Palzo ?, 



upper 28' impure) . . 802 to 860 



Gray shale 860 to 868 5 



Black shale 868 5 to 870 6 



Top of the Dekoven 



coal bed 870 6 



If the sandstone below coal No. 2 and 

 above the Dekoven coal beds is the Palzo 

 sandstone, the total thickness of the Car- 

 bondale strata in this drill hole is 221 feet 

 2 inches, since the base of Palzo sandstone 

 is considered to be the base of the Carbon- 

 dale group. 



Another diamond-drill core from sec. 16, 

 T. 6 S., R. 1 E., Franklin County, has a 

 thin coal bed which has been identified by 

 spores as the No. 2 coal bed. The follow- 

 ing is a generalized description of the coal 

 beds and other strata for a short distance 

 above and below No. 2 coal bed : 



Depth 



Ft. In. 



Base of McLeansboro . 562 S l /i 

 Top of Herrin (No. 6) 



coal bed.. 562 S% 



Top of Harrisburg 



(No. 5) coal bed.... 613 



Coal horizon 683 9 



Coal No. 4 (?)........ 702 



Limestone, fossilifer- 



ous 778 6 



Shale, fossiliferous . . . .779 4 



Limestone, fossiliferous 781 7 



Depth 

 Ft. In. 



to 61 A 

 to 704 



6 



to 779 

 to 781 

 to 782 



4 



7 

 



