90 



ILLINOIS STATE GEOLOGICAL SURVEY 



of Neuropteris flexuosa) of Read (1947) . 

 Bhardwaj (1957) considers the lower part 

 of the Illinois Carbondale Group as the 

 transition zone and Briar Hill (No. 5a) 

 and Herrin (No. 6) Coal as roughly 

 equivalent to seam 1 (Stolberg) of the Saar 

 and to the Velener Schicten (Lower West- 

 phalian D) of the Ruhr. 



Discussion of the large spore occurrences 

 is based on a study of 24 samples from 

 eleven Illinois counties. J. M. Schopf's ex- 

 tensive report on the megaspores from Her- 

 rin (No. 6) Coal is discussed below and 

 incorporated into the spore distribution 

 chart (text fig. 9) . Primary emphasis has 

 been placed on the coals of the Caseyville 

 and Tradewater Groups so that discussion 

 of those coals in the Carbondale and 

 McLeansboro Groups is held to a minimum. 



Colchester (No. 2) Coal 



Wanless (1955) stated that the Colches- 

 ter (No. 2) Coal is the most extensive 

 Pennsylvanian coal in the United States. 

 Unlike most other coals in Illinois, it has 

 its maximum development in the northern 

 part of the basin. 



The small spore content of the Colches- 

 ter (No. 2) Coal in northern, western, and 

 southern Illinois is uniform; the floral ele- 

 ments of the thinner coal in southern Illi- 

 nois are in approximately the same relative 

 abundance as in the thicker Colchester 

 (No. 2) Coal from western and northern 

 Illinois (Kosanke, 1950) . Samples of Col- 

 chester (No. 2) Coal (and probable No. 2 

 Coal) from nine localities were examined 

 for large spore content. The variation in 

 megaspore content between these coals is 

 marked. 



The following genera and species were 

 identified from the Colchester (No. 2) 

 Coal (macerations 824, 825, and 826), 

 more than 30 inches thick, outcropping in 

 Mill Creek, Schuyler County: 



Cystosporites giganteus (C, A, C) 



Monoletes (P, C. C) 



C. varius (P, C, P) 



C. breretonensis (P, C, P) 



Triletes rugosus (C, -, A) 



C. verrucosus (C, R, P) 



T auritus (A, -, ■) 



T triangularis (P, -, -) 



Calamospora cf. C. laevigata (P, -, - ) 



The sample from the bottom portion of 

 the bed is dominated by spores of Triletes 

 mgosus, accounting for about 50 percent 

 of the assemblage. Cystosporites spores 

 clearly dominate in the middle sample of 

 the bed. T. auritus is dominant in and re- 

 stricted to the upper 2 feet of the coal. T. 

 triangulatus and Calamospora cf. C. laevi- 

 gata also appear to be restricted to the 

 upper portion of the bed. The high inci- 

 dence of spores of T. rugosus and Cysto- 

 sporites parallels the reported dominance 

 (Kosanke, 1950) of the botanically related 

 small spores of Lycospora. 



Another outcrop sample of the Colches- 

 ter (No. 2) Coal 19 inches thick (macera- 

 tion 603 A-C) , from Fulton County, con- 

 tains all the genera and species of macera- 

 tions 824, 825, and 826, except Cystosporites 

 verrucosus. Triletes mamillarius is repre- 

 sented by rare spores in the bottom 4 inches 

 of the bed. In addition to a different 

 megaspore distribution throughout the 

 bed, Cystosporites seems to be less well 

 represented. 



Another sample of the Colchester (No. 

 2) Coal (maceration 899) from Fulton 

 County only contains abundant spores of 

 Monoletes and rare spores of Triletes 

 triangulatus. 



Four samples of Colchester (No. 2) Coal 

 from northern Illinois were examined. One 

 (maceration 579A-C) from the Spring Val- 

 ley No. 3 mine, Bureau County, had repre- 

 sentatives of the genera and species given 

 for macerations 824, 825, and 826 above, 

 except Cystosporites verrucosus and Tri- 

 letes auritus. In addition, Parasporit' j s is 

 known from the lower two-thirds of the 

 bed; however, as in macerations 824, 825, 

 and 826, Cystosporites and Monoletes are 

 dominant. 



Two samples from Grundy County ex- 

 hibit extreme variations in large spore con- 

 tent. One (maceration 611) contains spores 

 of Triletes rugosus, Monoletes, Calamo- 

 spora cf. C. laevigata, T. triangulatus, and 

 Cystosporites breretonensis. T. rugosus is 

 dominant; Monoletes is subdominant. The 

 other sample from Grundy County (macer- 

 ation 580) contains fairly abundant spores 

 of Cystosporites. Monoletes is rare, in 



