Wilmington Field Research Articles

An Interesting "Dadoxylon" from Northern Illinois

The object of this report is to record an interesting piece of fossil wood from the coal beds of northern Illinois. The specimen was collected in the spring of 1934 by the writer in company with Dr. Waldo E. Steidtmann during a collecting trip to the coal fields of east central and northeastern Illinois. It was found on the dump heap of the Northern Illinois Coal Co., several miles north of Braidwood, Will County; and a few miles east of Coal City, Grundy County, Illinois. This locality is in the eastern part of the Coal City-South Wilmington field of District No. I (Cady, 1915). The coal bed in this field is the socalled No. 2 vein (Noe, 1925, 1930; Cady, 1915) and is wide spread throughout this region. The shale above the coal contains fossil-bearing nodules or concretions, and many of these were collected from the dump heap along with the specimen of fossil wood. A few of the most common plants found in these concretions were, Annularia stellata, A. radiata, A. sphenophylloides, Sphenophyllum emarginatum, Lepidophyllum majus, Neuropteris rarinervis, N. decipiens, Pecopteris vestita, P. Miltoni, P. unita, Alethopteris Serlii, and others. White (1907a, b, 1908) made a preliminary study of the Paleozoic plants of Illinois; as a result of his observations the Pennsylvanian system in that state was divided into the Pottsville, Carbondale, and McLeansboro formations. Coal bed No. 2 is considered the base of the Carbondale, and No. 6 the top-most member. Noe (1925) has made a more complete study of the fossil flora of northern Illinois. From a comparison of the Pennsylvanian plants of Illinois with those of the Upper Carboniferous of Europe (Noe, 1930) the No. 2 coal seam (Carbondale) has been correlated with the uppermost Westphalien of Europe, and the Pennsylvanian formations above No. 2 with the Stephanien. The specimen of fossil wood was about the size of one's fist and formed the center core of a gray limestone rock which was over a food in diameter. The wood was calcified, and the preservation varied from good to poor in different parts of the material. A solid covering of calcium carbonate crystals, a little over one sixteenth of an inch thick, encased the whole specimen; in some places this intruded into the material causing some distortion and destruction of the wood. Small masses or mats of leaves and other plant remtiains were embedded in various parts of the rock, among whlich could be recognized such genera as Pecopteris and Neuropteris. The wood is all secondary and Cordaitean in character; and, for the