Early and mid-twentieth century coal-ball studies in North America
Tom L. Phillips, Aureal T. Cross, 1995. "Early and mid-twentieth century coal-ball studies in North America", Historical Perspective of Early Twentieth Century Carboniferous Paleobotany in North America, Paul C. Lyons, Elsie Darrah Morey, Robert H. Wagner
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Coal balls are concretions containing structurally preserved, coalified peat in coal beds; the plant tissues in coal balls are permineralized by calcite, dolomite, siderite, pyrite, or silica. The earliest known North American coal-ball studies, based on pyritic coal balls from Iowa, were carried out in the late 1890s by W. S. Gresley, a mining engineer from England. He utilized reflected light on polished surfaces to observe the anatomy of coal-ball plant constituents. Sustained development of studies began in the early 1920s at the University of Chicago as a result of calcareous coal-ball discoveries in the Illinois basin, reported by Adolph C. Noé. He was the leading advocate for the discovery and study of American coal balls, receiving assistance from state geological surveys and the coal-mining industry. Interests at the University of Chicago led to the establishment of a chair in paleobotany for Noé and ensuing coal-ball research by his students, J. Hobart Hoskins, Fredda D. Reed, Harriet V. Krick Bartoo, Roy Graham, and others. At the time there were very few paleobotanists in North America. Most pioneers in American coal-ball studies during the 1930s were self taught in paleobotanical research. Consequently, quite diverse perspectives of the significance and use of coal balls were represented. In the 1930s acid etching and the liquid-peel (Darrah solution) technique generally replaced thin sectioning; larger numbers of coal balls were discovered, partly as a result of increased open-pit coal mining. At the Illinois State Geological Survey such discoveries attracted James M. Schopf, who stressed the importance of coal balls as a paleobotanical index for the constitution of coal, a method of identifying the botanical sources of dispersed spores and pollen, as well as their use in a stratigraphic approach to monographic studies of Carboniferous plants. This approach is mirrored in the early monographic works of J. Hobart Hoskins and Aureal T. Cross at the University of Cincinnati. William C. Darrah at Harvard University was particularly interested in the paleofloristic and biostratigraphic information to be gained from coal-ball studies. He instituted mass peel preparations as well as splitting coal-ball specimens to reveal the morphology of associated foliage taxa. At Washington University in St. Louis, Henry N. Andrews emphasized anatomy and development in the evolution of the pteridophytes and early seed plants. American coal-ball studies in the upper Middle and Upper Pennsylvanian expanded by the early 1940s with collections from Iowa, Missouri, Kansas, Texas, Illinois, Indiana, and western Ken-tucky. Following World War II, research and training continued at Washington University with H. N. Andrews and developed anew at the University of Illinois with Wilson N. Stewart. This research led to new generations of paleobotanists during the following decades. In 1949, James M. Schopf established the U.S. Geological Survey’s Coal Geology Laboratory in Columbus, Ohio, and continued his influential role in coal-ball studies, encouraging and directly aiding such studies in the United States. In the 1950s the rapid-peel technique with preformed sheets of cellulose acetate expedited studies. The National Science Foundation became a significant source of support for such research, and paleobotany was more broadly represented in universities. Even into the 1960s, however, no one would have predicted how abundant coal-ball deposits in North America would prove to be, as the first occurrences were reported from the Appalachians and New Brunswick, Canada. In this chapter, these developments are described.
An epilogue is also provided, which outlines major initiatives and contributions of recent decades that bridge early- and middle-twentieth-century development of coal-ball studies in North America with those of the century to come.