Recent analysis of an abundant coal flora dislodged from "coalballs,'' or "sulphur balls" of the miners, obtained near Des Moines, reveals a number of fine flowers showing all the essential structures of present-day forms. These occur near the base of the local coal measures. Stratigraphically the horizon is very low in the Mid Carbonic general column. Above this level are now known no less than four miles of Des Moines coal shales, all of the Pennsylvanian coal series, of perhaps equal thickness, and all of the Missourian coal measures of corresponding thickness. This places the plant horizon only a few feet above the great erosional unconformity which planed off the Early Carbonic limestones and older strata, and carried the flowering plants twice the distance into the abyss of time than heretofore supposed or recorded. The determinations were made by Dr. William Darrah, of Harvard University, foremost paleobotanist of our clay, the particular specimens involved being collected by Mr. Frederick O. Thompson of Des Moines. A large amount of additional material located by Mr. Thompson and others awaits detail-inspection and description, the results of which will soon place Iowa in the forefront in this country m interest in histological study of coal measures plant structures.
Proceedings of the Iowa Academy of Science
©1939 Iowa Academy of Science, Inc.
"Oldest Flowering Plants are From Iowa,"
Proceedings of the Iowa Academy of Science, 46(1), 255-256.
Available at: https://scholarworks.uni.edu/pias/vol46/iss1/70