PAPERS OX GEOGRAPHY AND GEOLOGY 179 



COAL BALLS HERE AND ABROAD 

 A. C. Xoe, University of Chicago 



A coal ball is a calcareous or siliceous coal seam con- 

 cretion which frequently contains recognizable plant 

 fragments.* These plant fragments have furnished our 

 entire knowledge of the inner structure of paleozoic 

 plants. They have been observed since 1835 in England 

 where Williamson used them in his monumental studies 

 of fossil plants since 1875, a work which was continued 

 by D. H. Scott in England, C. D. Bertrand in France, 

 and many others. 



The existence in America of coal balls was suspected 

 by the author who succeeded in obtaining in 1922 the 

 first specimens of genuine American coal balls. These 

 came from Harrisburg, Illinois; later good specimens 

 were found in Danville, Illinois, in Calhoun (Richland 

 County), Illinois, and in Streator, Illinois. Other Ameri- 

 can deposits are in Iowa where coal balls showed up at 

 DesMoines, Indianola, and Chariton. Good specimens 

 were also collected by the author near Sturgis, Ken- 

 tucky, and at Cayuga, Indiana. They were found outside 

 of England, France, and America in Austria, Germany, 

 Russia, Czecho-Slovakia, Poland, and Australia. 



Of the American coal ball specimens from Harrisburg, 

 Danville and Calhoun thin sections have been made in 

 the botanical laboratory of the University of Chicago. 

 The following genera of fossil plants were observed and 

 their structure carefully examined: 



Harrisbunj — . Fern sporangia 



Sphenophyllum stem Root with spongy cortex 



Lepidodendron stem Peculiar leaf 



Lepidodendron sporangium Calamites leaf 



Stigmaria and rootlets Calhoun — 



Anachoropteris Sphenophvllum stem 



Angiospermophyton Calamites stem 



Root with spongy tissue Bothrodendron stem 



Fern sporangia and spores Microsporophvll and 



Calamites leaf, probably in all sporangium 



three places. Megosporophyll and 



Danville — sporangium 



Lepidodendron stem Stigmarion rootlets 



Lepidodendron sporangia Xumerous multeseriate fern, 



Stigmaria and rootlets (few) sporangia with spores 



Sturiella minor Lyginodendron stem 



* Jose Maria Fellclano, The Relation of Concretion to Coal Seams 

 (Journal of Geology, Vol. 32, pp. 230-239, 1924. 



